teratology (ga&e)

8/10/2019 Teratology (GA&E)

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GA&E

EMBRYOLOGY:

TERATOLOGY

Assoc Prof Dr Mohamad Aris Mohd Moklas (PhD)Department of Human AnatomyFPSK [email protected] 8947 2783


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The science that studies the causes of structura

functional, behavioral & metabolic disorders

present at birth:

- size,

- arrangement or- composition of any organ or part of the body.

Teratology


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Principles of teratology1. Susceptibility to teratogenesis depends on the genot

fetus & mother.

2. Susceptibility to teratogens varies with the developm

at the time of exposure. The most sensitive period for

birth defects is the 3rd 8th weeks of gestation, the per

embryogenesis or organogenesis.

Teratology


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Principles of teratology3. Manifestations of abnormal development depend on

duration of exposure to a teratogen.

4. Teratogens act in specific ways on developing cells &

initiate abnormal embryogenesis.

Teratology


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Teratology


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Types of anomalies

a) Visible deviations of structureb) Non-visible deviation or deviations of function

occurring as a result of enzyme deficiency which result in a

chemical functions called inborn errors of metabolism in

protein, carbohydrates, lipids & pigments.

a) Anomalies existing at birth or long before birth suc

congenital anomalies.

Teratology


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Incidence

a) The incidence of congenital anomalies vary with race

in different populations of the same race.

b) Some anomalies are more common in males such as

stenosis, cleft lip & hydrocephalus; and some anomamore common in femalessuch as congenital disloca

the hip, birth marks, anomalies of brain and spinal co

Teratology


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Frequency of congenital anomalies

a) Muscular-skeletal - 38 %

b) Integumentary - 20 %

c) CNS - 14 %

d) GIT - 9 %

e) Genito-urinary - 9%

f) Respiratory - 2 %

Teratology


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Class if icat ion of anomalies

(1) Failure of development: Agenesis

- an organ or body part may be subjected to developme

Teratology


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(1) Failure of development: Agenesis

Teratology


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(2) Incomplete development

- In growth: dwarfism, gigantism

- In union: cleft palate, double uterus

- In subdivisions: heart chambers, body cavities, double urete

kidneys, double gall bladders

- In metabolism: sickle cell anaemia

- In histological differentiation: thickened skin, stenosis

- In number: multiple digits, multiple nipples, twinning

Teratology


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(2) Incomplete development

Teratology

Gigantism & dwarfism Multiple breast synd


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(3) Embryonic persistence - any embryonic

structure which persist instead of disappearing

- Meckels diverticulum

- cervical cyst

- thyroglossal cyst


Teratology


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(3) Embryonic persistence

- Meckels diverticulum


Teratology


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(4) Misplacements ectopic thyroid, ectopic

pregnancy, ectopic testes


Teratology


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(4) Misplacements

- ectopic thyroid


Teratology


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The modern view on anomalies is based on two caus

1.Hereditary

2.Environment

Teratology



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1.Hereditary

(1) Genes

autosomal (dominant or recessive); X-linked (dominant or

(2) Chromosomes

- Non-disjunction (failure of chromosome pairs / chromatids to sep

during cell division.

- Eg: Turners syndrome (X monosomy) (45, X0) & Downs syndrom

Teratology



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2. Env ironment or teratogen ic agents

-Environmental factors cause 7 to10 % of congenital an

(1) Physical : external traumatic injuries

(2) Irradiation: X rays or atomic explosions(3) Chemical agents:

Drugs (thalidomide, anti-convulsants, social drugs)

Alcohol (alcohol fetal syndrome)

Teratology



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2. Env ironment or teratogen ic agents

(4) Hormones: thyroxine, diabetic mothers

(5) Heavy metals:

Mercury (mental retardation)

Lead (increased abortion, fetal anomalies, functional de

(6) Growth inhibitors: nitrogen mustard

(7) Vitamin deficiency

Teratology



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Polydactyly

Meromelia

Amelia

Downs Syndrome


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HoloprosencephalyCaudal dysgenesis

Anencephaly

Cleft lip

teratology (ga&e)

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