CHAPTER ONE
1.1 INTRODUCTION
Camels are in the taxonomic order Artiodactyls (even-toed ungulates), sub
order Tylopoda (pad-footed), and Family Camelidae (Wilson, 1984).They are
pseudo-ruminants that possess a three-chambered stomach, lacking the omasum
that is part of the four-chambered stomach of the order ruminantia (Hegazi,
1950).
Camels are important animals especially to the people of arid and semi arid
zones for many economic and agricultural purposes. They have been
traditionally used for transportation of people and goods, to supply hides and
skin, meat and milk products (Reece, 1997). One of the most advantageous
attributes of the camel in drought areas is its ability to utilize plants that grow
well under arid conditions which are unacceptable to other grazing animals
(Fowler, 1998b). Camelids evolved in North America and were separated from
primitive artiodactylids in the Eocene epoch period, approximately 40 million
years ago (Wilson, 1995; Wilson, 1997).
Though camels ruminate, they are not true ruminants, as they lack the
four well-defined stomach of the ruminants; the rumen, reticulum, omasum and
abomasum (Arnautovic, 1997). The role of the camel in the modern world is
changing with increases in human population, coupled with poor economic
potentials of some countries have transformed the traditional use of camel as
milk and meat source (Mukasa-Mugerwa, 1981; Khanna, 1990). The anatomical
development of all members of the Camelidae is considered to be similar but
most of the available data on the anatomy of the alimentary canal have been
obtained mainly from the Llama (Bustinza, 1979). From the anatomical
differences between the Camelidae and Bovidae, it was hypothesized that the
physiological processes in the alimentary canal would also differ (Bohlken,
1
1960). This was further emphasized by the difference in rumen protozoan
population between the camel and the sheep (Farid, et al., 1979).
In Northern Nigeria, where camels are slaughtered for human
consumption, the meat was found to rank second to that of cattle (Mustapha and
Oluyisi, 1993; Agaie et al., 1997; Sonfada, 2008).In East Africa, (Kenya,
Ethiopia, Sudan, and Somalia), camel, are bred for meat (Mukasa-Mugerwa,
1981) and are used mainly as traction animal, even though cattle are the most
predominant (Tukur and Maigandi, 1999).
1.2 Statement of Problem
There have been many studies on the quantitative value and histology of
digestive system in adult camel, (Asari et al., 1985; Wilson, et al., 1990; Reece,
1997; Bustinza, 1979; Franco et. al., 2004a) but similar studies have not been
conducted on the developmental changes of the entire digestive tract of the
camel fetus. There is thus, paucity of information on the developmental changes
of the digestive tract of dromedarian camel.
1.3 Justification of the Study
Since the importance of camel in its adaptation to its environment proves to
have so many relationships to the digestion and utilization of its food, there is,
therefore, need to study the anatomical development of the digestive tract for
better understanding of the animals habitat and management system so as to
enhance camel production in Nigeria.
There is also need to establish anatomical base-line information on the
development of gastrointestinal tract of the dromedarian camel fetus. The
information so generated will complement available literatures that were mostly
on Llama. The data obtained from this study will help to bridge the existing gap
on the morphology, morphometry and histology of the digestive tract of the
developing dromedarian camel.
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1.4 General Objectives
The general aim of this work is to study the Gross anatomy, morphometry and
histology of the digestive tract of dromedarian Camel fetuses.
1.5 Specific Objectives of the Study
The specific objectives of the study are:
To provide an information/data on gross anatomy of digestive tract (D/T) of
the developing dromedarian fetus.
Provide Morphometric data of the fetal digestive tract at different
developmental stages.
Determination of the microscopic features of various segments of the
digestive tract of one- humped camel fetuses.
To relate the structural findings to the function of various segments of the
digestive tract.
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CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 OVERVIEW
All the members of the camel family are found in the order of the Artiodactyla
(even-toed ungulates); suborder: Tylopoda (pad-footed); family: Camelidae.
The old-world genus is the Camelus, having the two species of the Bactrianus
(two-humped) and Dromedarius (one-humped). The new-world genus of the
Lama has three species, while the genus of Vicugna has only one species.
Though they chew cud, camels differ from true ruminants in a few anatomical
features (Cloudley-Thompson, 1969). Adult camels have two incisor teeth in
their upper jaws; they lack an omasum, the third stomach division of the
ruminants, which is considered the water reabsorbing portion of the stomach;
they have no gallbladder; and the hooves have been reduced to claw-like toes,
projecting beyond the pads (Zeuner, 1963).
Camel is an important animal especially to the people of Sahel savanna for
many economic and agricultural purposes. They have been traditionally used for
the transportation of people and other commodities, to supply hides and skin,
meat and milk products (Reece, 1997). One of the most advantageous attributes
of the camel in drought areas is its ability to utilize plants that grow well under
arid conditions and are unacceptable to other grazing animals (Dahlborn et.
al.,1987).
There are almost 14 million Dromedary camels alive today that are
domesticated animals, mostly living in Somalia, Sudan, Mauritania and nearby
countries (Malie et. al., 1987) .The Bactrian camel once had an enormous range,
however, it is now reduced to an estimated 1.4 million animals, mostly
domesticated. It is thought that there are about 1000 wild Bactrian camels in the
Gobi Desert in China and Mongolia. Humans first domesticated camels between
4
3,500 - 3,000 years ago (Bulliet, 1975). FDLPCS (1992) estimated a Nigerian
national annual mean population of 87,000 camels, being found most frequently
in the former Sokoto (43,960) and Borno (26,866) states. The same report also
found that 83.93% of all camels are found in the villages, depending on season.
The camel is morphologically, behaviorally and physiologically adapted to heat,
water shortage and poor quality fodder (Yagil 1984).
Unlike other domestic species where differentiation into types or breeds
started soon after domestication, and animals were selected for specific
economic traits that lead to changes in morphology, particularly size, shape and
colour, the camel never had such changes (Wilson, 1984). No breed differences
were recognized even though the camels were identified with the tribes that
bred them (Malie et. al., 1987; Duhan et. al., 1996). Tribal brands (Wasms)
were of particular importance in Arabia, Egypt and Sudan. Types of camel can
often be identified with the help of these marks; other wise even very
experienced camel men have difficulty in distinguishing types. It is more correct
to discuss camels in terms of ecotypes, associated to particular ethnic groups
(El-Amin, 1979; Wilson, 1984).
2.2 Camel Characteristics
Camels are camelids, members of the biological family Camelidae, the only
living family in the suborder Tylopoda. Camels tend to be large and are strictly
herbivorous but differ from ruminants in several ways (Wilson, 1984). Camels
have a three-chambered rather than a four-chambered stomach. They have an
upper lip that is partially split in two with each part separately mobile. Camels
also have an isolated incisor in the upper jaw (Wilson, 1998).The red blood
cells in camels are oval shaped, unlike those of other mammals which are
circular. This is to facilitate their flow in a dehydrated state. These cells are also
more stable in order to withstand high osmotic variation (the diffusion of water
5
through a cell wall or membrane) without rupturing when taking in large
amounts of water (Wilson, 1998).
A fully grown adult camel stands 1.85 metres (6 feet) at the shoulder and
2.15 metres (7 feet) at the hump. Camels can run up to 65 kilometres per hour
(40 miles per hour) in short bursts and sustain speeds of up to 40 kilometres per
hour (25 miles per hour).The life span of a camel is 30 to 60 years (Malie et. al.,
1987).
The kidneys of a camel are very efficient. Urine comes out as a thick syrup
and their faeces are so dry that these can fuel fires (Malie et. al., 1987; Wilson,
1998).Camels are able to withstand changes in body temperature and water
content that would kill most other animals. Their temperature ranges from 34°C
(93°F) at night up to 41°C (106°F) in the day and only above this threshold will
they begin to sweat. This allows them to preserve about five litres of water a
day. Camels can withstand, at least, 25% weight loss due to sweating (Wilson,
1998).
A feature of their nostrils is that a large amount of water vapour is trapped
when they exhale and this is returned to their body fluids, thereby reducing the
amount of water lost through respiration(Alexander and Robert, 1986). A
camel’s thick coat reflects sunlight. A shaved camel has to sweat 50% more to
avoid overheating. It also insulates them from the intense heat that radiates from
hot desert sand (Malie et al., 1987). Their long legs help by keeping them
further from the hot ground. Camels have tough feet so that they can endure the
scorching desert sands. Camels have also been known to swim if given the
chance (Sweet, 1965).
A camel’s mouth is very sturdy and it is able to chew thorny desert plants
(Alexander and Robert, 1986). Long eyelashes and ear hairs, together with
6
closeable nostrils, form an effective barrier against sand. Camels pace (moving
both legs on one side at the same time) and their widened feet help them move
without sinking into the sand (Sweet, 1965 ; Malie et al., 1987).All member
species of the Camelids are known to have a highly unusual immune system,
where part of the antibody repertoire is composed of immunoglobulins without
light chain. Whether and how this contributes to their resistance to harsh
environments is currently unknown (Malie et al., 1987).
2.3 Pregnancy diagnosis
In order to improve the efficiency and increase the economic viability of camel
breeding, it is important to know if and when the females are pregnant. This can
be done by rectal palpation (Chen and Yuang, 1979; Musa, 1979; Skidmore,
2000a) and by biological assay using infantile mice (Musa, 1979). The latter
method is only feasible at certain stages of pregnancy. The surest method is by
radio-immuno assay. Pregnancy determination is important in the care of the
females, the selection of males and in long-term planning.
2.3.1 Methods of pregnancy diagnosis
2.3.1a Tail "Cocking"
Several scholars have asserted that it is possible to detect pregnancy in camels
from as early as 15 days by observing an erected and coiled tail in the pregnant
animal when approached by a male camel (Ibrahim, 1990). This response has
been noted in unmated animals treated with exogenous progesterone and also in
younger animals that maybe alarmed by the male (Malie et al., 1987; Skidmore,
2000b).
2.3.1b Changes in Cervical Mucous
7
i) Viscosity - Other studies have shown that changes occur in pH and flow
elasticity of the cervical mucous in pregnant versus non-pregnant camels. The
cervical mucous tends to be turbid in most stages of the ovarian cycle, although
during oestrus it becomes less viscous, but not watery (Skidmore, 2000c). In
pregnant females the mucous becomes whitish and opaque and it decreases
gradually in amount until the second month when it becomes almost impossible
to collect (Ibrahim, 1990).
ii) pH - The pH varies between 6.74 and 7.36 during the follicular cycle in non-
pregnant camels but it becomes more alkaline during early pregnancy,
increasing from pH 7.05 after mating to as high as 8.2 at the beginning of the
sixth week of gestation (Ibrahim, 1990 ; Skidmore, 2000a).
iii) Specific Gravity - This was measured using the copper sulphate method and
was found to vary between 1.004 and 1.008 during the follicular phases in the
non-pregnant animal (Skidmore, 2000c). During pregnancy the specific gravity
also increased, rising from 1.009 after mating to 1.014 at the beginning of the
sixth week (Ibrahim, 1990).
However none of these methods mentioned above are very practical under field
conditions.
2.3.1c Rectal Palpation
Diagnosis of pregnancy using rectal palpation can present some risks to the
females such as rectal tears but it is not considered detrimental to the foetus
provided the examination is carried out by experienced personnel and the uterus
is not over manipulated. The membrane slip test, described in cattle pregnancy
diagnosis, is not possible in camelidae because of the diffuse type of
placentation (Skidmore, 2000b). Therefore positive pregnancy diagnosis can
only be achieved if the CL and foetus are palpated.
8
The earliest sign of pregnancy is the persistence of the CL which continues to
grow until day 35 of pregnancy.It is usually soft, flabby and spherical in shape,
measuring about 25 mm in diameter, but becomes out of reach after about 90
days (Ibrahim, 1990; Skidmore, 2000b).
It is not until about day 45, that uterine changes due to pregnancy can be
detected by rectal palpation and the first sign is an increase in the diameter of
the left horn (Skidmore, 2000c). However, it is not until approximately the third
month of pregnancy that the gravid horn feels obviously bigger and softer than
the non-gravid horn and the uterus becomes more abdominal as the amount of
foetal fluid increases. The cervix is pulled forward and lies just at the brim of
the pelvis at 4 months, and by the fifth month the uterus is completely in an
abdominal position with a small degree of fluctuation, but the foetus is not
always palpable (Skidmore, 2000c).
From 6th month onwards, the foetus can be palpated; first by ballotment,
then the head and legs become easily palpable as the foetus starts its ascent. By
the 9th month, movement can be observed by inspection of the right flank of the
animal and external signs such as an enlarged abdomen and udder are visible
from about the 11th month. Precise estimation of the stage of pregnancy by
rectal palpation in the dromedary is not possible beyond 3 months because of
the absence of structures such as cotyledons and difficulty in reaching the foetus
in this species (Skidmore, 2000a).
Pregnancy diagnosis in the Bactrian camel by rectal palpation is similar to
that of the dromedary as noted by Skidmore (2000c). The first sign indicating
pregnancy is a persistent corpus luteum, but it is not until 45 days that the first
palpable changes in the uterus are noticed. At around this time the left horn of
the uterus increases in size and is almost continuous with the uterine body.
Between 2.5 - 3 months, the tip of the left horn is out of reach but the
bifurcation between the uterine horns can still be felt, and this is also out of
reach by 4 months. By 5 months the uterus is in an abdominal position and the
9
foetus can only be balloted in a small proportion of females. A fremitus can also
be detected on the left uterine artery in 75% of the females. By 8 months, the
foetus becomes more easily palpable and the artery fremitus is felt on both
sides. Foetal activity seems to increase from the 9th month and from 11th
months to term, the foetus is high and always palpable (Ibrahim, 1990).
2.3.1d Ultrasonography
Realtime ultrasonography, using a 3.5 or 5 MHz transrectal linear array
transducer is now regarded as the method of choice for detecting pregnancy and
monitoring early foetal development in large domestic animal species
(Skidmore, 2000b).
In camelids, pregnancy diagnosis by ultrasonography is possible as early as
17 days of gestation. This diagnosis is based on two main criteria: the
visualization of an embryonic vesicle and the presence of a corpus luteum. The
corpus luteum has to be present to confirm pregnancy status unless the female is
getting exogenous progesterone. In the early stages of pregnancy, the embryonic
vesicle is relatively difficult to visualize because it is elongated, the embryonic
fluid is dispersed and the uterus is relaxed. The vesicle is however, almost
always in the left horn and is best visualized at the tip of the horn where it is
likely to have accumulated most fluid (Skidmore, 2000a).
By day 17 of gestation, the embryonic vesicle appears as a star-shaped small
accumulation of fluid within the uterine lumen (Ibrahim, 1990). As the stage of
the pregnancy increases, the embryonic vesicle increases in size and becomes
more visible and elongated in longitudinal view of the uterus (Ibrahim, 1990) or
more round in cross section (Ibrahim, 1990). The embryo then becomes visible
between days 20 - 22 as a small, echogenic speck within the fluid fixed at one
pole of the vesicle (Ibrahim, 1990) and the heartbeat becomes discernible
between days 23 - 25 as a small fluttering within the echogenic speck of the
foetus.
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2.4 Gestation
Yasin and Wahid, (1957) reported a gestation period of 365 to 395 days in
dromedarian camel. It has a range of 370 to 405 days with an average of 388
days.The period of gestation for female calves averages at 390 days, while for
males 385 days.Lower limit for survival of foetus is 350 days. Calves born at or
just before this time may appear weak but otherwise normal for the first 24
hours post partum but then go into irreversible decline surviving only for 2 to 3
days. The gestation period of the Bactrian camel is 402 days (Chen and Yuang,
1979).Average pregnancy duration in the Bactrian is about 400 days.
2.5 Foetal Development
The camel embryo elongates quickly and soon protrudes from the left horn onto
the right uterine horn. Videoscopic studies showed allantochorion to be in left
horn at day 20 which extended into the right by day 25 (Skidmore, 2000a).Chen
and Yuang, (1979) show that, examination at day 44 showed the exposed
surface of the allantochorion to have a roughened and hazy appearance,
presumably due to the development of simple chorionic villi in the process of
implantation and placentation. When examined by the transmission electron
microscope, these villi are present on the trophoblast cells of embryos as young
as 7 days. At 44 days the tail and four limb buds are visible on the foetus and
the head, eye, umbilical cord and heart beat are discernible (Skidmore, 2000a).
At 55 days the allantochorion is thickened and spotty and presses on the internal
os of the cervix. The foetus is clearly seen to have rudimentary bones and a
more camel-like head and neck. Blood vessels are also more developed by now
(Skidmore, 2000a). When the FBL (foetus body length) is 1 to 10 cm, the
allantoic fluid volume is 1.5 litres. When FBL is 90 cm, fluid volume is 5 to 6
litres and finally reaches about 8.5 litres when the FBL is 100 to 107 cm and the
fluid resembles pale urine (Skidmore, 2000a). When the FBL is 0 to 10cm, the
volume of amniotic fluid is 13 ml. It increases to a volume of about 1 litre at 11
parturition. The fluid may be watery or cloudy due to the presence of meconial
debris. The extra close fitting of epidermal membrane becomes apparent when
FBL reaches 41cm. It closely envelops the foetus but leaves the orifices open to
the true amnion. It appears to be a major source for the relative ease of birth in
the camel (Skidmore, 2000a).
2.6 The camel digestive tract
Although camels ruminate, they are not true ruminants, as they lack the four
well-defined stomachs of the ruminants- the rumen, reticulum, omasum and
abomasum. The anatomy of all members of the Camelidae is considered to be
similar but most of the available data on the anatomy of the alimentary canal
have been obtained mainly from the Llama (Malie et al., 1987 ; Sonfada, 2008).
Lesbre (1903) and Leese (1927) stated that the camel has only three
compartments compared with the bovine's four compartments (Phillipson, 1979)
i.e. the missing compartment being the omasum, or third compartment. Hegazi
(1950) describes the camel as having the same four compartments as other
ruminants, but with the external constrictions between the omasum and
abomasum being less well defined in the camel. Sonfada, (2008) stated that the
Llama and guanaco stomachs consist of only three compartments.
The salivary glands of the camel have the same grouping as in cattle, but are
slightly darker in colour morphologically (Malie et al., 1987). The arrangement
of the glands, however, is different. The parotid glands are in the same position
in camels as in cattle, but in camels, the maxillary gland is located under the
parotid gland and jugular vein and over the pharyngeal lymph glands (Leese,
1927). The gland does not extend under the throat as it does in cattle. The
sublingual glands are smaller than those of cattle and are situated along the root
12
of the tongue. The buccal glands are well developed, and have dorsal and
ventral portions.
When comparing the mouth of the camel with that of cattle, the outstanding
differences are the very supple lips of the camel, the long prominent papillae,
and canine teeth. The oesophagus enters the rumen directly (Vallenas, et al.,
1972).
Much has been written about the internal anatomy of the camel stomach. The
stories of camels being slaughtered for water in the stomach (Bohlken, 1960)
led to the belief that the rumen, contained water cells (Leese, 1927). It was
assumed that these water cells were able to store water (Colbert, 1955; Hegazi,
1950; Leese, 1927, Schmidt-Nielsen, et al., 1956). This theory was disputed by
Vallenas, et al., (1972) the sac-like compartments were found in the caudal part
of the first compartment, the rumen. It has been suggested that the main
function of this glandular region of the fore-stomach is the rapid absorption of
solutes and water (Engelhardt and Rubsamen, 1979).
The suggestion that the glandular areas of the rumen contain accessory
salivary glands (Schmidt-Nielsen, et al., 1964) has not been substantiated. The
mucous layer, which covers the surface epithelium, may have a mainly
protective function (Engelhardt and Rubsamen, 1979). The bicarbonate
secretion of these glands (Eckerlin and Stevens, 1972) was not substantiated in
later experiments (Engelhardt and Rubsamen, 1978).
The camels forestomach is quite different. Although it is divided into three
parts, carrying the neutral names; compartments 1, 2 and 3, which are analogous
in function to the rumen, reticulum and abomasum respectively, it differs
anatomically in many respects from the forestomach of the Ruminantia.
Compartment 1 is not papillated nor strongly subdivided by muscular pillars
13
like the rumen, compartment 2 is not lined by the honeycomb structure of the
reticulum, and compartment 3 is not globular nor filled with laminae like the
omasum. Instead compartments 1 and 2 possess many deep and muscular
saccules lined by a smooth mucous epithelium and the tubular compartment 3
has longitudinal folds also lined by a mucous epithelium. Dehydration allows
them to forage in a much wider circle around watering points than cattle or
sheep. (Hoppe et al., 1975)
The surface of most of the first and second compartments is lined with a
non-papillated stratified, squamous epithelium (Vallenas, et al., 1972).
Glandular epithelia can be found in the ventral portions of the first two
compartments and covering the entire third compartment. The glandular area in
the first compartment is restricted to the bottom of the saccules, and this area
was found to be smaller in camels than in llamas. In addition, the pouches in the
camel's rumen are smaller than those in the llamas (Franco et al., 1993a).
In the adult llama, the contents of the first two compartments account for 10–15
percent of the animal's body weight, and the third compartment for a further 1–2
percent. It is therefore clear that the intestines must contain at least an additional
5 percent of the body weight (Engelhardt and Rubsamen, 1979). Then the total
contents of the camel's alimentary canal will account for 25 percent or more of
the animal's body weight. The liquid contents in the alimentary canal are the
source of water for the thirsty camel (Yagil and Etzion, 1979).
The function of the numerous endocrine cells in the stomach wall is
unknown but it is possible that these cells play an important role in the control
of the water and electrolyte balance of the camel during dehydration (Yagil and
Etzion, 1979).
14
From the anatomical differences between the Camelidae and Bovidae it was
hypothesized that the physiological processes in the alimentary canal would also
differ (Bohlken, 1960). This is further emphasized by the difference in rumen
protozoan population between the camel and the sheep (Farid, et al., 1979).
Entodinium comprises 70 percent of the rumen protozoan population in both
animals, while Holotricha accounts for 10 percent of the population in sheep,
but was absent in camels. Epidinium is present in camels, but absent in sheep
rumen. The interesting fact was that during water restriction the Entodinium
population and total protozoan count decreased in sheep, but in camels the
Entodinium population increased and the total count remained virtually
unchanged.
2.7 Physiology of the digestive tract
The extremely mobile lips of the camel and the tough mucosa of the mouth
enable the animals to graze thorn bushes. The branches are stripped of their
leaves and the thorns present no problem.
In the mouth, the feed is mixed with saliva. The size and structure of the
salivary glands and the composition and flow of saliva from the glands are all
comparable with what is found in cattle (Engelhardt and Rubsamen, 1979).
Camel saliva is slightly hypotonic and the bicarbonate content is high
(Engelhardt and Rubsamen, 1979). When the animal is dehydrated a quarter of
body weight is lost. The parotid gland secretions then decline to a fifth of the
normal flow (Hoppe, et al., 1974). In the camel, as in all ruminants, the urea
formed from the protein metabolism is recycled to the stomach via the saliva. In
addition, the camel also obtains urea via the rumen epithelium itself (Houpt and
Houpt, 1968; Franco et al., 1992). The urea nitrogen is important as it is
assimilated into microbial protein which is a source of protein for the animal
following hydrolysis in the small intestines (Emmanuel, 1979).
15
Camel saliva was collected by allowing the animals to chew a clean dry
sponge and then examined for amylase content (Nasr, 1959). It was found that
the saliva has less amylase than that of man, pig or rat. This, however, is
different from cattle saliva which has no amylase (Schwart and Steinmetzer,
1924) whereas it is present in buffalo saliva (Nasr, 1959). Of all the glands, the
parotid glands have the most amylolytic activity, the submaxillary glands the
least and the sublingual glands none being mucous glands.
The contractions of the first and second compartments begin with a
contraction of the second compartment (Engelhardt and Rubsamen, 1979). This
is similar to the relationship of reticulum and rumen in cattle. In camels the
contents of the dorsal portion of the rumen are relatively dry. The ventral
portion of the cranial and glandular sacs in the reticulum, contain semi fluid and
watery ingesta (Ehrlein and Engelhardt, 1968; Ehrlein and Engelhardt, 1971;
Vallenas and Stevens, 1972).
Following the first single contraction of the reticulum, there is an immediate
contraction of the caudo-ventral region of the rumen and the glandular sacs
(Engelhardt and Rubsamen, 1979).The caudo-dorsal rumen contracts, followed
by the cranial sacs. This first set of contractions is followed by additional
contractions. The duration of a cycle is 1–2 minutes in the resting llama. The
rate increases when the animal feeds. The contractions and movements of each
cycle begin with a contraction of the reticulum. During contraction of this
compartment contents are moved from the reticulum to the caudal sac of the
rumen. From here part of the contents re-enter the reticulum and part goes into
the cranial sac, when the caudal sac contracts. When the cranial sac contracts,
its contents move back into the caudal sac. The motility of camel's fore-stomach
is radically different from that of cattle (Ehrlein and Engelhardt, 1968).
16
Rumination and eructation occur three to four times during every cycle
(Ehrlein and Engelhardt, 1971; Engelhardt and Rubsamen, 1979). Rumination
begins after the maximal contraction of the cranial rumen sac. Eructation takes
place near the peak of the caudal sac contraction.
In the camel's fore-stomachs, the volatile fatty acids (VFA) produced are
efficiently neutralized, probably by the glandular secretions as reported by
Vallanas and Stevens, 1972. A high concentration of VFA is found in the
Camelidae rumen (Maloiy, 1972; Vallenas and Stevens, 1972; Williams, 1963).
The various proportions of VFA are similar to those found in the rumen of cattle
(Maloiy, 1972). This suggests a great similarity in metabolism in the fore-
stomachs of camels as compared with other ruminants. Motility studies,
however, indicate that there is no precise similarity between the species
(Vallenas and Stevens, 1972) and were verified in comparative studies between
the camel and the Zebu (Maloiy, 1972). It was found that the camel has a lower
digestive efficiency of low quality hay, assumed to be caused by a more rapid
passage of food through the stomachs. Camels fed on straw (Yagil and Etzion,
1980a), however, not only grow better but digest the food better than most cows
(Personal observation). Digestibility of medium quality hay was no different in
the llama and in sheep (Franco et. al., 1992). In the digestive studies, the most
important finding was that the fluid volume of the fore-stomach and the rate of
outflow of fluid from the stomachs to the intestines were far greater in the camel
than in the Zebu (Maloiy, 1972). Water-deprived sheep lost far more rumen
water than camels (Farid, et al., 1979). Water dynamics in the alimentary canal
of the camel allow it to survive and produce during dry periods. The alimentary
water provides a reservoir that is tapped slowly in order to maintain a relatively
unchanged extra cellular volume and provides the fluid which dilutes the milk
(Yagil and Etzion, 1979; Yagil and Etzion, 1980a and b). The anatomical
17
differences between camels and other ruminants could account for the much
slower water turnover in the camel (Macfarlane, 1977).
Sodium chloride and VFA were found to be rapidly absorbed from the
rumen of the llama (Engelhardt and Sallman, 1972 and Franco et. al., 2004a).
The absorption rates in the llama were three times greater than the absorption in
sheep and goats. Absorption occurs mainly in glandular areas of the fore-
stomach. In the third compartment solutes and water are absorbed (Franco et.
al., 2004a; Ali and Wipper, 1979). The absorption rates of sodium, VFA and
water in this tubiform compartment were found to be far greater than the
absorption rate in the omasum of sheep and goats.
According to Engelhardt, et al. 1977 who said that the pH is very low in the
abomasum with an estimated segregation of water reaching 15 percent of the
amount that was absorbed in the omasum.
Comparative experiments carried out at the Desert Research Institute in
Egypt by Farid, et al., 1979 showed that the camel managed far better than
sheep on a low-protein, roughage diet and restricted drinking water regimen.
The sheep were allowed to drink every three days, the camels every twelve
days. The camels needed less water than the sheep for every unit of dry matter
consumed or per unit body mass. The camels also had a lower water intake than
Zebu cattle according to Maloiy, 1972. During deprivation studies, camels lost
far less water in urine and feces than did sheep (Farid, et al., 1979).
The camels digested dry matter and crude fibers better than the sheep. The
sheep, however, utilized crude protein better than the camels. The sheep
increased their feed intake during dehydration. The nitrogen metabolism of the
camel was superior, and this was even more apparent during water restriction
owing to the reduced nitrogen excretion in both faeces and urine. The sheep
18
were only able to reduce the nitrogen excretion in urine. The endocrine cells and
secretory cells in the rumen of the camel could account for the added nitrogen
retention capabilities (Engelhardt and Rubsamen, 1979). These data also
reinforce the theory of endocrine control of the alimentary canal, kidneys and
mammary glands affecting the water, salt and nitrogen metabolism (Yagil and
Etzion, 1979; Yagil and Etzion, 1980a and b), the ADH being responsible for
the flux of water and urea-nitrogen, the aldosterone for the flux of sodium.
The decline of nitrogen in both faeces and urine and the renal loss of sodium
allow the camel to maintain a relatively unchanged extra cellular volume. The
flow of water in the same direction with the urea-nitrogen accounts for the
lower amount of feacal and urinary water in the camel, when compared to the
Zebu steer (Maloiy, 1972) or sheep (Farid, et al., 1979). The camel has thus a
far more efficient nitrogen conservation mechanism than other ruminants
(Emmanuel, 1979). Even on a low-protein diet, nitrogen fixation in the rumen
and constant recycling of urea contribute significantly to a steady protein
synthesis. Twelve days of dehydration in the camel were equal to two days of
dehydration in sheep, as far as recycling of urea was concerned (Farid, et al.,
1979). The most pertinent result of the experiment was that the sheep did not
survive the experiments while the camels were unaffected.
Another important difference with other ruminants is that camels have a
significantly higher blood glucose level (Emmanuel, 1979). This may be
caused, in part, due to the anatomical differences in alimentary canals
(Engelhardt and Rubsamen, 1979), although VFA production was high in the
camel's fore-stomachs (Engelhardt and Rubsamen, 1979; Maloiy, 1972). Other
metabolic factors may play a role in the glucose handling by the camel and also
the hygroscopic properties of glucose may play a significant role as was
demonstrated in glucose-loading trials (Franco et al., 2004a).
19
Salt makes up a very important part of the camel's diet (Hartley, 1979).
Nomadic tribes are especially careful to ensure that the camel obtains sufficient
salty plants to eat. Salt is an important factor in the passage of water and urea in
the gut and the kidneys (Yagil and Etzion, 1979). Inadequate salt diet will lead
to less milk production in camels (Mares, 1954) which becomes even more
important when drinking water is restricted (Yagil and Etzion, 1980b).
2.8 Feeding habits
The camel covers large areas while browsing and grazing, and is continually
on the move, even if food is plentiful. Distance of 50–70 kilometers a day can
be covered (Newman, 1989). Camels in the Horn of Africa still range for their
food even though they are brought to graze on crop residues, such as Sorghum
stover, cotton stalks and sesame waste (Hartley, 1979).
The main forage is obtained from trees and shrubs. The diet is made up of
species of Acacia, Indigofera, Dispera, and Tribulus. The Acacia, Salsola and
Atriplex plants which contain the highest content of moisture, electrolytes and
oxalates are preferred (El-Amin, 1979). It is noteworthy that most of the
preferred plants are not readily eaten by other animals because they are thorny
and bitter. In Africa (Newman, 1989), shrubs and forages make up 70 percent of
the diet in winter and 90 percent in the summer.
2.9 Camel Physiological Adaptation
The physiological mechanisms, which allow the camel to survive periods of
over two weeks without drinking water and to eat the most unpalatable plants,
have to do with the conservation of water. It is of interest that severe desiccation
is tolerated. Up to 30 percent of its body weight can be lost by loss of water -
20
amounts that would be fatal in the case of other farm animals or even man
(Schmidt-Nielsen, 1964). Moreover, this loss can be replenished in a matter of
minutes (Yagil et al., 1974). The camel has the lowest water-turnover of all
animals (Macfarlane, 1977) and is able to regulate water and salt uptake from
the colon and their excretion from the kidneys (Yagil and Etzion, 1979). Camels
do not need to sweat to lower their body temperature, thus conserving water
(Schmidt-Nielsen, 1964). The camel increases its body temperature from 34°C
in the early morning to over 41°C in the late afternoon, at which time the
environment cools greatly. Thus the camel stores its heat during the day and
cools off by conduction and convection in the evening. The water-deprived
camel reduces its metabolism (Schmidt-Nielsen et al., 1956; Yagil et al., 1975)
which also conserves water.
21
CHAPTER 3
MATERIALS AND METHOD
3.1 AREA OF STUDY AND STUDY DESIGN
The study was conducted in Sokoto metropoly through daily visitation to
the Sokoto metropolitan abattoir for a period of six (6) months (January-June,
2010). The study involved an evaluation of thirty- five (35) digestive tract of
dromedary camel fetuses harvested from slaughtered female pregnant camels.
The uteri of female camels slaughtered were examined at post-mortem to
determine pregnancy as reported by Malie et al., 1987. Fetuses from gravid
uteri were recovered and transported to Veterinary Anatomy laboratory. Each
fetus was examined grossly to rule-out any abnormality such as congenital
abnormalities and trimming of fetal membranes; followed by sexing, ageing and
weighing of the fetuses.
3.2 FETAL AGE ESTIMATION
The age of the fetuses were estimated biometrically using a formula [GA
= (CVRL + 23.99)/0.366] as described by El-Wishy et al. (1981), where GA is
the gestational age (in days). This was done by taking the length of the crown
vertebral- rump length which is from the point caudal (posterior) fontanel to the
base of the tail following the vertebral curvature (in centimeters) using
measuring tape (Butterfly brand) to substitute in the above formula.
3.3 DISSECTION OF THE FETUS
Chibuzor (2006) method was used for the dissection of the fetuses. These
were done by placing the fetus on dorsal recumbency and a mid-ventral skin
incision (linear alba) at abdomino-pelvic region across the thoracic region up to
the neck at the inter-mandibular space was made. The entire digestive tract and
22
individual segments of the system (tubular and accessory) was dissected out,
identified and the morphometric values were recorded.
3.4 MORPHOMETRICAL INVESTIGATION
The morphometrical procedures employed in this study involved dividing
the segment of the digestive tract into eleven components, namely; oesophagus,
smooth part of the rumen (dorsal), coarse part of the rumen (ventral), reticulum,
abomasum, duodenum, jejunum, ileum, caecum, colon and rectum (Luciano et
al.,1979). The length and diameter of the oesophagus, duodenum, jejunum,
ileum, caecum, colon and rectum were measured and dissected out. The length,
width and volume of the rumen, reticulum and abomasum were also measured.
Observing and measuring the crown vertebral-rump length (CVRL) in
centimeter. This was done using measuring tape (butterfly brand) by placing the
free-end at the anterior fontanel and running it over the vertebral column to the
base of the tail.
Measuring the weight of the fetuses (FW), weighing the entire digestive system
(D/S), weighing the accessory digestive system (ADS) and weighing the
digestive tract (D/T) using compression spring balance (AT-1422), size C-1,
sensitivity of 20 kg X 50g in Kilogram.
Measuring the length of the various segments of the D/T of each fetus using
butterfly measuring tape in centimeter; and Measuring the diameter of the
various segments of the D/T of each fetus using divider (for smaller segments)
and meter ruler (for bigger segments) in centimeter.
Measuring the volume of the stomach using water displacement technique
(Archimedes’ principle) in cubic centimeter (Luiz and Jose, 2005).
23
3.5 HISTOLOGY
Two cubic centimeters (2 cm3 ) of each segment of the GIT was trimmed
and kept in labeled bottle containing 10% formal saline as a fixative (Barbara
and John, 2000); the tissues were then kept to stay on the table for two days to
allow proper fixation. Thereafter, the tissues were processed using normal H &
E preparation (Drury et al., 1967). (Appendix II).
3.6 PHOTOMICROGRAPHY
The prepared sectioned slides were examined and photographed using
motic camera 2.0 with 1.30M pixel (digital motic cam Camera at different
magnifications of the microscope).
3.7 DATA PRESENTATION AND STATISTICAL ANALYSIS
Data obtained were presented in mean + standard error of mean and
student-t test was employed to analyse the data using SPSS version 17.0
statistical soft ware.
24
CHAPTER FOUR
RESULTS
4.1 Fetal Study
Of the thirty five (35) fetuses at different gestational age used for the
study, twelve (34.3%) were females while twenty three (65.7%) were males.
From the observations, 13(37.14%) fetuses belong to first trimester, 11(31.42%)
belong to second trimester and 11(31.42%) belong to third trimesters of
pregnancy respectively. The mean crown vertebrate-rump length (CVRL)
ranges from 20.06 ± 3.0 cm for fetuses of first trimester, 60.27± 4.0 for fetuses
of second trimester and 103.83 ± 6.0 cm for fetuses of third trimester as shown
in table 1.
The weight of the camel fetus at all three phases of gestation (first, second and
third trimesters) were observed to increase as the animal advanced in age.
The mean body weight of the foetus ranges from 1.40 ± 0.06 kg, 6.10 ±
0.05 kg and 17.87 ± 0.6 cm at first, second third trimester respectively. The
mean weights of the entire digestive system at first, second and third trimester
were 0.80 ± 0.07 kg, 2.13 ± 0.04 kg and 4.86 ± 0.08 kg respectively. The mean
weights of the digestive tract at first, second and third trimester of age were 0.53
± 0.07 kg, 1.03 ± 0.05 and 2.43 ± 0.07 kg respectively (Table I).
4.2 Morphology of the digestive tract (D/T)
Fetuses considered to be in the first trimester (0 -4 months) had physical
features as, the abdomen appeared transparent with some organs appearing dark,
an indentation of the eye buds, ear buds and jugular veins were prominent. The
calvaria were very soft and transparent. The CVRL ranged from 13 – 40 cm,
while the weight ranged from 0.8 kg to 2.3 Kg. (Plate 1)
Fetuses at second trimester (4 – 8 months) have well developed eyes and ears.
Hairs were on the lower eyelid and ear margins. Hairs developed on the lips
25
(upper and lower), the calvarium was hard but soft at the fontanels (cranial and
caudal), Mammary buds and vulva was prominent in female at this stage. The
scrotal sacs became more prominent with structures being palpable. The CVRL
and body weight ranged from 40 to 80 cm and 4 to 9 kg respectively (Plate 2).
The fetuses of third trimester (8 – 12 months) had their whole body covered
with short hair initially except at the inner thigh. The hair continued to grow as
the fetus advanced in age. The skull at this level was strong, on palpation. The
CVRL at this stage was above 80cm (85-120), while the weight of the fetus
ranged from 11 to 29.15 kg (Plate.3).
26
Plate 1: Photograph showing camel fetus at first trimester with transparent abdominal
wall, rudimentary ear canal opening and eye indentation X 75
27
Plate 2: Photograph showing camel fetus at 2nd trimester with thick prominent skin (A)
and hair on the upper eyelid (B) and head region. X 75
28
Plate 3 Photograph showing camel fetus at 3rd trimester with short densely distributed
hair (whitish) all over the body with very small areas of alopecia (black
arrow). X 75
29
The camel digestive tract comprises of the oesophagus, stomach {rumen
(coarse and smooth), reticulum and abomasum}, small intestine (duodenum,
jejunum and ileum), and large intestine (caecum, colon and rectum), (Plate 4,5
and 6).
In the first trimester fetuses, the digestive tract was observered to have all the
component i.e. oesophagus, stomach {rumen, reticulum and abomasum}, small
intestine and large intestine; however, there was no clear demarcation between
segments of the small intestine i.e. duodenum, jejunum and ileum as shown in
plate 7 and 10.
The digestive tract of the second trimester fetuses showed to have clear
demarcation of the small intestine in to duodenum, jejunum and ileum and
prominent demarcation of the stomach in to dorsal smooth and ventral coarse
parts as shown in plate 8 and 11.
As shown in the plate 9 and 12, fetuses of the third trimester had similar
developing structures as in that of the second trimester fetus. In addition, all the
components are highly developed with segment filled with muconeum.
30
Plate 4: Photograph showing abdominal cavity organs of camel fetus at first trimester
insitu X 75
31
Plate 5: Photograph showing abdominal cavity organs of camel fetus at second
trimester insitu X 75
32
Plate 6: Photograph showing abdominal cavity organs of camel fetus at third trimester
insitu X 75
33
Plate 7: Photograph showing the entire digestive tract of camel fetus at first trimester
X 75
34
Plate 8: Photograph showing the entire digestive tract of camel fetus at second
trimester X 75
35
Plate 9: Photograph showing the entire digestive tract of camel fetus at third trimester
X 75
36
Plate 10: Photograph showing the entire digestive tract of camel fetus at first trimester
with no clear demarcation in the small intestine (duodenum, jejunum and ileum) (A),
caecum (1), colon (2) and rectum (3)
37
3
2
1
A
Plate 11: Photograph showing the entire digestive tract of camel fetus at second
trimester with clear demarcation in the stomach and small intestine, oesophagus (1),
reticulum (2), rectum (3), colon (4), abomasum (5), coarse part of the rumen
(6) ,smooth part of the rumen (7), duodenum (8), jejunum (9), ileum(X), caecum (Z).
38
8
4
52
9
z
X
1
3
6
7
Plate 12: Photograph showing the entire digestive tract of camel fetus at third
trimester showing oesophagus (A), ,smooth part of the rumen (B), coarse part of the
rumen (C), reticulum (D), abomasum ((E), duodenum (F), jejunum (G), ileum (H),
caecum (I), colon (J) and rectum (K).
39
H
K
AEF
B
CD
G
J
I
4.3 Morphometric values of the digestive tract (G I T).
From the study, the digestive tract index ranges from 37.86 at the first
trimester to 13.60 in third trimester, while the digestive system index ranges
from 57.14 at the first trimester to 27.20 in third trimester fetus as shown in
Table I.
Morphometrically, the digestive tract was divided into oesophagus,
stomach; rumen, reticulum and abomasum, small intestine; duodenum, jejunum,
and ileum, large intestine; caecum, colon and rectum as shown in plate 10, 11
and 12.
As shown in table II, the mean lengths of the oesophagus ranges from 13.83
± 2.33cm in first trimester to 52.13 ± 2.67cm in the third trimester. The mean
lengths of the rumen, reticulum and abomasum ranges from 7.47 ± 1.67 cm,
1.97 ± 0.43 cm and 12.67 ± 2.33 cm at first trimester to 20.75 ± 1.33 cm, 6.93 ±
0.27 cm and 25.75 ± 0.37 cm at third trimester respectively.
As shown in plate 7 and 10, the small intestine at first trimester were found
not to have any clear demarcation to show duodenum, jejunum and ileum; the
entire small intestine was found to be 76.00 ± 3.00 cm at first trimester and
showed clear demarcation at second and third trimesters; with the duodenum,
jejunum and ileum found to be 66.00 ± 2.00 cm, 139.50 ± 3.00 cm and 75.00 ±
3.00 cm in the third trimester respectively.
There was clear demarcation between the components of the large intestine
in all the phrases of gestation as shown in plate 7-12. The mean lengths of
caecum, colon and rectum ranges from 9.33 ± 0.30cm, 65.00 ± 3.00cm and
8.33 ± 0.30cm at the first trimester to 40.75 ± 3.33cm, 164.75 ± 3.00cm and
30.00 ± 2.33cm in the third trimester respectively as shown in table II.
As shown in the table III, the mean diameter of the oesophagus ranges from
0.30± 0.04 cm in the first trimester to 1.30± 0.80 cm in the third trimester. The
mean width of the rumen, reticulum and abomasum ranges from 1.93 ± 0.17cm,
1.00 ± 0.40cm and 1.33 ± 0.20cm in the first trimester to 11.50 ± 1.00cm, 4.05
40
± 0.20cm and 4.25 ± 0.30cm in the third trimester respectively. The mean
diameter of the small intestine at first trimester was 0.30 ± 0.01cm while at third
trimester, the mean diameter of the duodenum, jejunum and ileum were 1.18 ±
0.03cm, 1.20 ± 0.03cm and 1.23 ± 0.03cm respectively.
The mean diameter of the caecum, colon and rectum ranges from 0.33 ±
0.03cm, 0.33 ± 0.01cm and 0.40 ± 0.04cm at first trimester to 2.55 ± 0.03cm,
1.60 ± 0.03cm and 3.28 ± 0.03cm in the third trimester respectively.
The mean volumes of the entire stomach (rumen, reticular and
abomasum) ranges from 136.67 ± 8.30 cm3 at first trimester to 353.33 ± 6.50
cm3 at third trimester as shown in table II.
Table I: Mean CVRL, Mean fetal weight (FW), Weight of the Digestive system (D/S)
and mean weight of the Digestive tract (D/T), of fetuses at various
trimesters
Parameters First Trimester Second Trimester Third Trimester
Number of sample (N) 13 11 11
CVRL (mean±SEM) 20.06 ± 3.0 60.27 ± 4.0 103.83 ± 6.0
Fetal weight (FW) (Kg) (mean±SEM)
1.40 ± 0.06a 6.10 ± 0.5b 17.87 ± 0.6c
W/DS (Kg) (mean±SEM)
0.80 ± 0.07a 2.13 ± 0.04b 4.86 ± 0.08c
W/DT (Kg) (mean±SEM
0.53 ± 0.07a 1.03 ± 0.05b 2.43 ± 0.07c
D/S index (%) 57.14 34.91 27.20
D/T index (%) 37.86 16.89 13.60
abc: means on the same row with different superscripts are significantly different (P < 0.05).
41
Table II: Mean Lengths of the different segment of the Digestive tract (D/T and
volume of the stomach compartment at various trimesters.
Parameters First Trimester Second Trimester Third Trimester
Oesophagus(cm)
(mean±SEM)
13.83 ± 2.33a 31.83 ± 2.00b 52.13 ± 2.67c
Stomach (cm)
Rumen (mean±SEM) 7.47 ± 1.67a 13.83 ± 1.67b 20.75 ± 1.33c
Reticulum (mean±SEM) 1.97 ± 0.43a 3.47 ± 0.47b 6.93 ± 0.27c
Abomasum(mean±SEM)
Volume (mean±SEM)
( cm3)
12.67 ± 2.33a
136.67± 8.30a
18.33 ± 0.40b
283.33± 6.50b
25.75 ± 0.37c
353.33± 7.65c
Small intestine (cm)
Duodenum(mean±SEM) 44.83 ± 2.67b 66.00 ± 2.00c
Jejunum(mean±SEM) 76.00 ± 3.00 111.67 ± 3.33b 139.50 ± 3.00c
Ileum (mean±SEM) 59.33 ± 2.67b 75.00 ± 3.00c
Large intestine (cm)
Caecum (mean±SEM) 9.33 ± 0.30a 28.00 ± 3.00b 40.75 ± 3.33c
Colon (mean±SEM) 65.00 ± 3.00a 110.33 ± 3.00b 164.75 ± 3.00c
Rectum (mean±SEM) 8.33 ± 0.30a 18.00 ± 2.00b 30.00 ± 2.33c
abc: means on the same row with different superscripts are significantly different (P < 0.05).
42
Table III: Mean widths/ diameters of the Digestive tract segments at various
trimesters.
Parameters
First Trimester
Second Trimester Third Trimester
Oesophagus(cm)
(mean±SEM) 0.30± 0.04 a 0.70± 0.20b 1.30± 0.80c
Stomach (cm)
Rumen (mean±SEM) 1.93 ± 0.17 a 6.43 ± 0.43 b 11.50 ± 1.00c
Reticulum(mean±SEM) 1.00 ± 0.40 a 2.63 ± 0.30 b 4.05 ± 0.20c
Abomasum(mean±SEM) 1.33 ± 0.20 a 3.00 ± 0.23 b 4.25 ± 0.30c
Small intestine (cm)
Duodenum (mean±SEM) 0.80 ± 0.05b 1.18 ± 0.03c
Jejunum (mean±SEM) 0.30 ± 0.01 0.83 ± 0.02b 1.20 ± 0.03c
Ileum (mean±SEM) 0.80 ± 0.03b 1.23 ± 0.03c
Large intestine (cm)
Caecum
(mean±SEM)
0.33 ± 0.03 a 1.13 ± 0.03b 2.55 ± 0.03c
Colon (mean±SEM) 0.33 ± 0.01 a 0.77 ± 0.02 b 1.60 ± 0.03c
Rectum
(mean±SEM)
0.40 ± 0.04a 1.00 ± 0.03 b 3.28 ± 0.03c
abc: means on the same row with different superscripts are significantly different (P < 0.05).
43
4.4 HISTOLOGY
Histologically, observation of the tissues in this study revealed a complete
structure of the tubular organ. The oesophagus was found to consist of four
layers namely: (1) Tunica mucosa, (2) Tunica sub mucosa, (3) Tunica
muscularis and (4) Tunica adventitia /serosa. At the first trimester, only three
layers were identified, that is; Tunica mucosa, Tunica muscularis and Tunica
adventitia. At the beginning of the second trimester, the orientation changed,
resembling that of the adult with all the four layers prominent i.e. Tunica
mucosa, Tunica sub-mucosa, Tunica muscularis and Tunica adventitia. At the
third trimester, the Oesophageal gland appeared prominently in the tunica sub-
mucosa resembling that of the adult camel (slide 1).
The Tunica mucosa epithelium was simple squamous epithelium at first
trimester and began to change at second trimester to stratified squamous
epithelium. At third trimester, the epithelium was keratinized stratified
squamous epithelium with the oesophageal (sub-mucosal) glands appearing to
be prominent and abundant.
The tunica muscularis showed clearly a single layer at second trimester
while at third trimester; both inner circular and outer longitudinal layers
appeared. The tunica adventitia was typical. Blood vessels and nerve fibres
became well visible at the tunica muscularis and sub-mucosa in third trimester
fetuses (slide 1).
The proximal compartment of the camel stomach was the rumen and grossly
is divided into two parts at first trimester; the dorsal smooth part and the ventral
coarse part.
The ventral coarse part showed a progressive fold at the tunica mucosa
and sub-mucosa with advance in gestation. In the first trimester, there was no
clear difference in the tunica mucosa epithelium. At the second trimester, it
showed clearly the appearance of stratified squamous epithelium with numerous
blood vessels in the tunica sub-mucosa. The tunica muscularis showed clear
44
demarcation of inner circular and outer longitudinal arrangement. At third
trimester, the surface of the tunica mucosa showed numerous projections or
elevation and depression resembling the intestine. The tunica serosa was typical
in both trimesters as shown in slide 2.
The dorsal smooth part showed fewer folds than the ventral coarse part
with only three distinct layers in first trimester. Tunica mucosa epithelium at
first trimester was simple squamous epithelium, the tunica muscularis did not
show any division into inner circular and outer longitudinal, while at second
trimester the tunica mucosa epithelium was of typical stratified squamous
epithelium and the tunica muscularis was composed of inner circular and outer
longitudinal layers. At third trimester, the epithelium was keratinized stratified
squamous epithelium with numerous blood vessels in the tunica sub-mucosa
and tunica muscularis. There was no much secretory or defensive cell in the
sub-mucosa as shown in slide 3.
As shown on the slide 4, the reticulum showed similar disposition with
the rumen i.e. with two district areas. The nature of epithelium, the tunica
mucosa, tunica sub-mucosa, tunica muscularis and tunica serosa had the same
disposition but the fold and projection in the surface of the ventral coarse part
were much prominent than in the rumen.
The abomasum showed an abrupt change in the orientation with a typical
four basic layers. The tunica mucosa epithelium at second trimester showed
stratification with tunica muscularis being composed of inner circular layer and
outer longitudinal layer. At the 3rd trimester, the epithelium in the tunica mucosa
became simple columnar epithelium with a clear distinct tunica muscularis
layer. Numerous lymphatic’s cells, blood vessels and nerves were found in the
tunica sub-mucosa at both 2nd trimester and 3rd trimester fetuses as shown in
slide 5.
The small intestine showed four basic layers too. The surface of the
epithelium showed numerous villi proving more extensive in 2nd and 3rd
45
trimesters in both segments of the small intestine. The duodenum, as shown on
Slide 6, showed numerous projections called the villi with less prominent crypts
in both second and third trimester of age. The villi showed numerous branching
and taller in the jejunum (slide 7) than in the duodenum (slide 6) and ileum
(slide 8).
The tunica muscularis was typical at 2nd and 3rd trimesters having both
inner circular and outer longitudinal layers. At 1st trimester, the tunica
muscularis did not differentiate in to these two parts (slide 6, 7 and 8). All the
four layers were well developed at 3rd trimester fetuses. There were numerous
blood vessels in the tunica sub-mucosa and tunica muscularis of the small
intestine (slide 6, 7, and 8).
The large intestine showed a typical appearance of four (4) basic layers:
the tunica mucosa, tunica sub-mucosa, tunica muscularis and tunica serosa.
There was present of villi in the caecum and colon (slide 9).The epithelium of
the caecum, colon and rectum at 1st trimester showed stratification (pseudo-
stratified epithelium) with tunica muscularis comprising only of single
longitudinal layer (slide 9, 10 and 11). The tunica sub-mucosa of both caecum
and colon had numerous aggregates of lymphatic tissues at both 2nd and 3rd
trimesters. The tunica muscularis showed distinct area of inner circular and out
longitudinal layer in both 2nd and 3rd trimesters, (slide 10 and 11).
A distinct layer of skeletal muscle in the rectum of 2nd and 3rd trimester
fetuses was observed. Numerous aggregate of lymphatic tissues were found in
the sub-mucosa layer of the rectum as shown in slide 11.
46
4.5 HISTOLOGICAL OBSERVATION
A
B C
Slide 1: Transverse section of the oesophagus showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow), G-Oesophageal gland, A- 1ST Trimester, B- 2nd
Trimester, C- 3rd Trimester, 150x
47
G
G
G
A B
C
Slide 2: Transverse section of the coarse rumen showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow), V-Blood vessel, A- 1ST Trimester, B- 2nd Trimester,
C- 3rd Trimester 150 x.
48
V
A
B C
Slide 3: Transverse section of the smooth rumen showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester, 150
x.
49
A
B C
Slide 4: Transverse section of the reticulum showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow) A- 1ST Trimester, C- 3rd Trimester, 150 x.
50
A B
C
Slide 5: Transverse section of the Abomasum showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester,
150 x.
51
A
B C
Slide 6: Transverse section of the duodenum showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester, 150
x.
52
A
B C
Slide 7: Transverse section of the Jejunum showing long villi with branching of microvilli,
Epithelium (Black arrow), Submucosa (Blue arrow), internal (circular) layer of
tunica muscularis (Red arrow), external (longitudinal) layer of tunica muscularis
(Green arrow), serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd
Trimester, 150 x
53
A
B C
Slide 8: Transverse section of the Ileum showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester,
150 x.
54
A B
C
Slide 9: Transverse section of the Caecum showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester,
150 x.
55
A
B C
Slide 10: Transverse section of the Colon showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red arrow),
external (longitudinal) layer of tunica muscularis (Green arrow), serosa (White arrow)
A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester, 150 X.
56
A
B C
Slide 11: Transversal section of the Rectum showing Epithelium (Black arrow),
Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red
arrow), external (longitudinal) layer of tunica muscularis (Green arrow),
serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester, 150
x.
57
CHAPTER FIVE
5.0. DISCUSSION.
5.1 GENERAL OBSERVATIONS
The current study attempted to increase the information about the normal
development of the camel digestive tract. From the results obtained in the
study, it was observed in general that there was increase in body weight, organ
weight and individual segment of the digestive tract in the fetuses with
advancement in gestation period. This is in agreement with the observations of
Warner, 1958, Jamdar and Ema, 1982 and Sonfada, 2008. They observed
obvious body weight increase with advancement of gestation period in different
specie of animals. Danlardi and Riddell, 1991 have also highlighted that
nutritional status and health condition of the dam play a vital role in the
development of the fetus hence increase in weight of the fetus.
5.1 Morphology
From the study, camels’ digestive tract observed comprises of the
oesophagus, the rumen (coarse and smooth parts), the reticulum, abomasum,
duodenum, jejunum, ileum, caecum, colon and rectum. This was inline with the
observations of many scholars (Luciano et al., 1979 and Sukon, 2009) but
contrary to the findings of Lesbre, 1903 ; Mayhew and Ctruz-orive, 1974 who
reported that during the development of the camel fetus, the abomasum had a
constriction or demarcation that showed a primitive omasum but disappear at
post-natal period.
The long and narrow oesophagus with relatively slight variation in the
diameter with regions observed in the study was in line with the findings of
Luciano et. al, 1979 and Sukon, 2009 who divide the regions of the oesophagus
in to five segments due to the size and shape of the oesophagus. The variation in
the diameter of the oesophagus at the developmental stage morphologically,
was in line with the finding of Luciano et al., 1979, who study the digestive
58
tract of Llama at prenatal stage and concluded that there was increase in
thickness in the oesophagus with advancement in gestation.
The division of the camel stomach into 3 major compartments i.e. rumen,
reticulum and abomasum as there was no omasum; in line with the
characteristic of the true ruminants with four chambered stomach is in line with
the finding of Luciano et al., 1979 and Belknap, 1994, who observed that the
abomasum was a long narrow tube-like structure with no constriction and
contrary to the findings of Mayhew and Ctruz-orive, 1974 who reported that
during the development of the camel fetus, the abomasum had a constriction or
demarcation that showed a primitive omasum but disappear at post-natal period.
The absence of demarcation or distinguishing features of small intestine at
first trimester into duodenum, jejunum and ileum grossly, but clearly
distinguishable at second and third trimesters was contrary to that of Llama
which showed clear difference in these segments at the middle of the first
trimester (Belknap, 1994). Nasr, 1959 reported that, most of the monogastric
mammals including rodents with short gestational periods show differentiation
of the small intestine into duodenum, jejunum and ileum, from the middle first
trimester. The gradual transformation in both size and shape of the small
intestine based on age distribution in camel fetus observed was in line with the
finding of Luciano et al., 1979 who reported that, in llama, the duodenum was
short compared to the other segments and the jejunum at first trimester showed
small number of coiling compared to second and third trimesters.
The differentiation of the large intestine into caecum, colon and rectum as
observed from the study from the early first trimester with a gradual increase in
size and shape was observed in most specie (llama, guanaco, buffalo, dog cat
sheep and pig). The diameters of ileum in small intestine and colon in the large
intestine were found to be almost identical at both first and second trimesters;
there was no report on such finding in any specie of animal. The moderately
long rectum observed in the study was in line with that of Llama (Belknap,
59
1994) and Guanaco (Cummings et al., 1972), when compared to the features
given for ruminant and other monogastric animals and this may likely be in line
with the adaptive features of desert animals.
5.2 MORPHOMETRIC STUDY.
The observed increase in weight, length and diameter of various segments
of the digestive tract in the study is in line with the findings of bovine, porcine
and caprine specie by Franco et al., 1993a; Bal and Ghoshal (1972) and
Georgieva and Gerov, (1975) respectively. The digestive tract indices observed
in the study showed significant difference in relation to the age (P≤ 0.05) and
the indices were decreasing with advancement in gestation (body development)
and similar developments were seen in the study of Georgieva and Gerov,
1975 ; and Bal and Ghoshal 1972 in pocine specie.
The progressive increase in length and diameter of the oesophagus based on
gestation period is in line with the observations of Belknap, 1994 and Franco et.
al.,1993c on the oesophagus of Llama and showed to have significant difference
in relation to the age (P≤ 0.05) The observed increase in lengths and widths of
the rumen, reticulum and abomasum in this study showed to have significant
difference in relation to the age (P≤ 0.05) and is in line with the observations of
Franco et. al., 1993a, Franco et al., 1993b and Franco et. al., 1993c; who study
the developmental anatomy of red deer stomach based on gestational period.
A geometrical increase in length and diameter of the various segments of
small intestine and large intestine as observed in this study showed to have
significant difference (P≤ 0.05) with advancement in gestation and was in line
with the findings of porcine (Vivo and Robina, 1991), bovine (Franco et. al.,
1993c and Knospe, 1996), buffalo (Asari et. al., 1985) and Llama (Belknap,
1994).
5.3 HISTOLOGY
In accordance with the finding of Hebel, 1960, Mutoh and Wakuri, 1989,
and Vivo et al., 1990 who studied the comparative Anatomy of the digestive
60
tracts of pig, cattle, sheep, dog and cat; red deer, goat; and cattle respectively,
the oesophagus was found to consist of four layers namely (1) Tunica mucosa,
(2) Tunica sub mucosa, (3) Tunica muscularis and (4) Tunica advantatia /serosa.
Franco et al., 2007 added that the development of this layers based on stages of
development was clearly in quick succession, but from the result, all the four
layers were developed at first trimester of age. The presence of highly
developed oesophageal glands within the sub mucosal layer with a prominent
tunica muscularis at second and third trimester was in line with the findings of
Sukon, 2009 on the Llama and Hebel, 1960 on the sheep and cattle. This may
likely be as a result of the nature of food of the animals.
The appearance of the keratinized stratified squamous epithelium at the
dorsal (smooth) part of the rumen and a columnar epithelium with deep tubular
glands on the ventral (coarse) part, which was referred to as the glandular area,
may likely be the water cell as observed by Sukon, 2009 on the Llama stomach.
The absence of glands /secretory cells in the sub mucosa of the smoother part of
the rumen and reticulum was also in line with that of the guanaco and Llama by
Luciano et. al.,1979 and Sukon, 2009 respectively. The structural appearance of
the rumen and reticulum in both dorsal and ventral portions were found to be
similar. The presence of columnar epithelium at the coarse portion of the rumen
and reticulum indicate a high ability of water absorption in the animal in
keeping with the adaptive features of desert animals. The above finding was in
agreement with the findings of Luciano et. al., 1979 on guanaco and Llama but
is contrary to the finding of Asari et al., 1980 on bovine, Hayward, 1967 on
rabbit and Franco et al., 2007 on porcine.
The small intestine of camel showed clear resemblance to that of a
tubular organ and conformed to organs with four basic layers. One of the most
characteristic features of small intestine is the presence of villi; the nature of
villi in camel showed a conical shape appearance. The villi in duodenum were
almost similar in appearance with these of the ileum, but those of the jejunum
61
were taller and numerous. All the features showed improvement with
advancement in gestation. This finding was in line with those of Luciano et al.,
1979 and Sukon, 2009 on Llama. The development of duodenum, jejunum and
ileum at first, second and third trimesters showed clear improvement in
succession from first, second and third trimesters with the third trimester
resembling that of an adult camel. The above finding was in line with that of
Sukon, 2009 but contrary to the finding of Hayward, 1967 on rabbit.
From the research work, the development of camels’ large intestine
showed differences with the result documented for sheep, goat, dog and horse
by having villi in the caecum and colon. This may be the reason for the
characteristic of dry faeces of camel following more absorption of fluid in the
area.
62
CHAPTER SIX: CONCLUSION AND RECOMMENDATIONS
6.1 Conclusion
The development of the camels’ digestive tract based on embryonic
stage was morphologically in succession.
From the study, the small intestine at first trimester was not divided in
to duodenum, jejunum and ileum morphologically.
The gross anatomy and morphometrical parameters of GIT were
established.
The developmental features of the camels’ digestive tract showed
similarity with that of features reported for Llama.
Several unique features of developing digestive tract prove adaptive
features of the animal to its environment and mode of feeding.
The camels’ stomach had little/few similarities with true ruminant
based on development.
The information obtained in this study will serve as a base-line data for
the specie in this environment.
6.2 Recomendation
Ultrastructural studies of the gastrointestinal tract of the developing
camel are recommended for detailed investigation.
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Appendix I: Materials
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- Polythene bag.
- Hand glove.
- Measuring tape.
- Electrical weighing balance.
- Specimen container.
- Bone cutter.
- Microtome.
- Oven.
- Water bath.
- Refrigerator.
- Glass slides.
- Cover slips.
- Microscope.
- Wooden chocks.
- Specimen bottles.
- Forceps
- Surgical blade & holder
- Seeker
- L-mould and plate
- Chemical balance
- Watch glass
- Measuring cylinder
- Beakers.
- Haematoxylin.
- Eosin.
- Glycerol.
- Distilled water.
- Paraffin wax.
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Appendix II: TISSUE PROCESSING
Tissues are fixed in 10% formal saline for 3-4 days. Tissues were trimmed
to 5-7 mm thick and wash in running tap water for 2 hours. Rinse in distilled
water and dehydrated through ascending grades of ethanol (35%, 50%, 70%,
95% and absolute ethanol). There were pre-cleared in xylene + Ethanol and
cleared in xylene. Tissues were transferred to molten paraffin wax + xylene in
the oven for filtration/impregnation. Tissues were embedded in pure paraffin
wax and allowed to solidify. Embedded block of tissues were mounted on the
wooden chocks and trimmed on microtome. Ribbons of section cut at 5 μm
thickness were placed on warm water in the water bath at 45oC to flatten the
tissues and picked on smeared albumin slides and dried in the oven at 45oC.
HAEMATOXYLIN STAINING
Chemical composition
- Haematoxylin 2g,
- Glycerol 200ml
- Potassium alum 20g
- Absolute alcohol 200ml
- Distilled water 400ml
- Acetic acid 10ml
- Sodium iodide 0.6g
PREPARATION
Haematoxylin is dissolved in absolute alcohol and Dissolve the potassium
alum in distilled water using heat if necessary. Mix the two solutions and add
glycerol then stir. Quickly add the sodium iodide to ripen the solution, allow
stand for 30 minutes and add the acetic acid to sharpen the nuclear stain. Filter
before use.
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PROCEDURE
Dewax and re-hydrate the sections tissue in water. Stain in
haematoxylin for 10 minutes; wash off the excess stain in running tap water.
Rinse in distilled water and differentiate in acid alcohol for 30 seconds. Blue
nuclei in alkaline alcohol for 5 minutes. Counter stain in eosin for 5 minutes.
Dehydrate in absolute alcohol and clear in xylene and mount in synthetic resin.
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