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•• Endocrine system regulates metabolic activities Endocrine system regulates metabolic activities ��������

help in bring out homeostasishelp in bring out homeostasis33

•• Nervous & endocrine systems functions in different Nervous & endocrine systems functions in different

way way ��������interact to modulate & coordinate metabolic interact to modulate & coordinate metabolic

activities of bodyactivities of body33

•• Secretory products/hormones secreted into:Secretory products/hormones secreted into:1, 21, 2

��Blood or lymphatic circulation Blood or lymphatic circulation

��Directly into intercellular spaceDirectly into intercellular space

•• Rich in vascular supply, secreting cellsRich in vascular supply, secreting cells�������� direct access direct access

to cappilllariesto cappilllaries22

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1.1. DUCTLESS GLANDS (pituitary DUCTLESS GLANDS (pituitary

gland/gland/hypophysishypophysis, adrenal gland, , adrenal gland,

parathyroid gland, thyroid gland, pineal parathyroid gland, thyroid gland, pineal

gland)gland)2, 32, 3

2.2. UNICELLULAR ENDOCRINE CELLS UNICELLULAR ENDOCRINE CELLS �������� form a form a

diffuse endocrine system (e. g: In GI tract, diffuse endocrine system (e. g: In GI tract,

conducting airways of lung)conducting airways of lung)2, 32, 3

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Testes

Ovaries

Classic Endocrine GlandsClassic Endocrine GlandsClassic Endocrine GlandsClassic Endocrine GlandsClassic Endocrine GlandsClassic Endocrine GlandsClassic Endocrine GlandsClassic Endocrine Glands

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•• Lying in sella turcicaLying in sella turcica22

•• Produces hormones responsible for regulating Produces hormones responsible for regulating growth, reproduction & metabolismgrowth, reproduction & metabolism33

•• Hypophysis subdivision :Hypophysis subdivision :1, 2, 31, 2, 3

A. ADENOHYPOPHYSIS (anterior pituitary)�� epithelial component :epithelial component :

-- Pars distalis Pars distalis �� anterior lobeanterior lobe

-- Pars intermediaPars intermedia

-- Pars tuberalis Pars tuberalis

B. NEUROHYPOPHYSIS (posterior pituitary)�� nervous component :nervous component :

-- Pars nervosa (major part)Pars nervosa (major part)

-- Infundibular stalkInfundibular stalk

-- Median eminence Median eminence

•• Posterior lobe Posterior lobe �� Pars intermedia + pars nervosa Pars intermedia + pars nervosa 22

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9Figure 18.6a, b

•• 75% of hypophysis75% of hypophysis11

•• Composed of cords of cells with large Composed of cords of cells with large sinusoidal cappilariessinusoidal cappilaries33

•• Endothelial lining of sinusoids Endothelial lining of sinusoids ��fenestrated fenestrated �� fascilitates diffusion of fascilitates diffusion of releasing factors & provides entry sites releasing factors & provides entry sites for secretionsfor secretions33

•• 2 kind of cells base on affinity for dyes :2 kind of cells base on affinity for dyes :1, 1,

2, 32, 3

1. Chromophobic cells1. Chromophobic cells

2. Chromophilic cells :2. Chromophilic cells :

-- Acidophilic cellsAcidophilic cells

-- Basophilic cellsBasophilic cells

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• Most abundant cells in pars

distalis3

• Structure :2, 3

� Large, round or ovoid cells

� Lage secretory granules stain

orange to red with eosin

• 2 KIND OF CELLS 11

� Secretory granules stain with histological dyes ���� stain with acid dyes or stain with basic dyes3

o Secretory granules stain blue with

basic dye3

o Located at periphery of pars distalis3

o Consist of 3 types of cells :2, 3

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• Small, No granules2

• Less cytoplasm than chromophils

�Fail to color with routine stains2,

3

• Degranulated chromophilic

• A reservoir of chromophilic cells2

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�� Non secretory, star shape cellsNon secretory, star shape cells

�� Constitute large population of pars distalisConstitute large population of pars distalis

�� Have long processes Have long processes �� form gap junctionform gap junction

�� Function not clear Function not clear

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ChromophilicChromophilic

cellscells

Acidophilic Acidophilic

cellscells

SomatotropeSomatotrope cellscells

Mammotrope cellsMammotrope cells

Basophilic Basophilic

cells cells

CorticotropesCorticotropes cellscells

Thyrotropes cellsThyrotropes cells

GonadotropesGonadotropes

cellscells

FSH FSH

secreting secreting

cells cells

LH secreting LH secreting cellscells

ChromophobeChromophobe cellscells

FolliculostellateFolliculostellate cellscells

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•• Forms a sleeve, around infundibular stalkForms a sleeve, around infundibular stalk22

•• Longitudinally arranged cords of cuboidal to Longitudinally arranged cords of cuboidal to

low collumnar epithelial cells separated by low collumnar epithelial cells separated by

sinusoidssinusoids1,2, 31,2, 3

•• Basophilic cytoplasm, small den Basophilic cytoplasm, small den

se granules, with lipid dropletsse granules, with lipid droplets33

•• No spesific hormone secretedNo spesific hormone secreted 2, 32, 3

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•• Rudimentary in humans, only 2% Rudimentary in humans, only 2%

of hypophysisof hypophysis22

•• Consist of :Consist of :2, 32, 3

1.1. Chromophobe cellsChromophobe cells

2.2. Basophil cells Basophil cells �� small granulessmall granules

3.3. ColloidColloid--containing cysts containing cysts ��lined by lined by

chromophobic or basophilic cell chromophobic or basophilic cell

(cuboidal cells)(cuboidal cells)

•• Function of cells is unknownFunction of cells is unknown1, 21, 2

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•• Develops from a downgrowth of Develops from a downgrowth of

hypothalamus hypothalamus

•• Macroscopically Macroscopically �� consist of consist of ::22

1.1. Median EminenceMedian Eminence

2.2. Infudibular StalkInfudibular Stalk

3.3. Infundibular Process (pars nervosa)Infundibular Process (pars nervosa)

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•• TecnicallyTecnically not endocrine glandsnot endocrine glands33

•• Hormones synthesized in Hormones synthesized in perikaryaperikarya of neurons of neurons supraopticsupraoptic& & paraventicularparaventicular nuclei in nuclei in hypothalamus hypothalamus �� pass down pass down axon axon �� stored in nerve stored in nerve terminals that form pars terminals that form pars nervosanervosa22

•• Consist of Consist of unmyelinatedunmyelinated nerve nerve fibers/axons fibers/axons �� forms forms hypothalamohypothalamo--hypophysealhypophyseal tracttract1, 1,

22

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•• Axon contain Axon contain HERRING BODIES ����accumulation of dense neurosecretory accumulation of dense neurosecretory granulesgranules2, 32, 3

• Pituicytes :1, 2, 3

��Scattered among nerve fibersScattered among nerve fibers

��25% of pars nervosa25% of pars nervosa

��Only nuclei stain well enoughOnly nuclei stain well enough

��Vary in size & shapeVary in size & shape

��Equivalent to neuroglial cells of CNS Equivalent to neuroglial cells of CNS �� supported axons in pars nervosasupported axons in pars nervosa

•• Hormones stored & released from pars Hormones stored & released from pars nervosa :nervosa :22

-- ADH / VasopressinADH / Vasopressin

-- OxytocinOxytocin

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•• A pair of flattened, triangular structA pair of flattened, triangular struct2, 32, 3

•• Surrounded by thick conn. Tissue capsule Surrounded by thick conn. Tissue capsule

�� forms trabeculaeforms trabeculae

•• Consist of adrenal cortex & adrenal Consist of adrenal cortex & adrenal

medullamedulla2, 32, 3

•• A yellow pheripheral layerA yellow pheripheral layer11

•• 8080--90% of organs90% of organs3 3

•• Parenchyma : continous cords of secretory Parenchyma : continous cords of secretory

cells, separated by blood sinusoidscells, separated by blood sinusoids22

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•• Subdivided into 3 layerSubdivided into 3 layer ::1, 21, 2

1. Outer zona glomerulosa1. Outer zona glomerulosa

2. Middle zona Fasciculata2. Middle zona Fasciculata

3. Inner zona reticularis3. Inner zona reticularis

1. Zona glomerulosa :1, 2, 31, 2, 3

�� A narrow band beneath capsule, A narrow band beneath capsule, 15% of organs15% of organs

�� Small Collumnar cells arranged Small Collumnar cells arranged into arcadesinto arcades

�� Spherical, central nuclei & 1 or 2 Spherical, central nuclei & 1 or 2 nucleolinucleoli

�� Acidophilic cytoplasm Acidophilic cytoplasm �� SER >>, SER >>, well develop golgi comp., short well develop golgi comp., short mitochondriamitochondria

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2. Zona Fasciculata :1, 2

�� Widest zone of cortex Widest zone of cortex �������� 6565--80% of 80% of organsorgans

�� Polyhedral Cells larger than in other Polyhedral Cells larger than in other 2 zone 2 zone �� arrange in radial collumsarrange in radial collums

�� Spherical & centrally nuclei, Spherical & centrally nuclei, binucleate binucleate

�� Cytoplasm with many lipid droplets Cytoplasm with many lipid droplets ��lipid eliminated during lipid eliminated during stainningstainning��appear vacuolated appear vacuolated ��cells called cells called SPONGIOCYTESPONGIOCYTE

�� Lipid droplets contain neutral fat, Lipid droplets contain neutral fat, fatty acids, fatty acyl esters of fatty acids, fatty acyl esters of cholesterol cholesterol �� precursor for precursor for synthesize steroid hormones synthesize steroid hormones

�� Spherical mitochondria, extensive Spherical mitochondria, extensive SER, some RER, lysosomesSER, some RER, lysosomes

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3. Zona Reticularis :1, 2, 3

�� 7% of organs 7% of organs

�� A network of irregular A network of irregular

anastomosing cordsanastomosing cords

�� Similar cells to fasciculata Similar cells to fasciculata

except smallerexcept smaller

�� Acidophilic cytoplasm, Acidophilic cytoplasm,

contain fewer lipid dropletscontain fewer lipid droplets

�� Nuclei stain more deeplyNuclei stain more deeply

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•• Hormones secreted by Hormones secreted by ::1, 21, 2

1.1. Zona glomerulosa : mineralcorticoids primarily Zona glomerulosa : mineralcorticoids primarily aldosteronealdosterone

2.2. Zona Fasciculata : glucocorticoids cortisone and Zona Fasciculata : glucocorticoids cortisone and cortisolcortisol

3.3. Zona reticularis : glucocorticoids cortisone and Zona reticularis : glucocorticoids cortisone and cortisol (probably)cortisol (probably)

•• Cells of adrenal cortex NOT store secretory Cells of adrenal cortex NOT store secretory products in granules products in granules �� synthesize & secrete synthesize & secrete

steroid hormone only upon demandssteroid hormone only upon demands11

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•• Composed of Composed of Chromaffin cells & sympathetic ganglionic cells33

• CHROMAFFIN CELLS ::1, 21, 2

��A large round or polyhedral cellsA large round or polyhedral cells

��Numerous brown granules Numerous brown granules ��treated with chromium salts treated with chromium salts (chromaffin reaction)(chromaffin reaction)

��Granules may contain epinephrine Granules may contain epinephrine or norepinephrine (20% of or norepinephrine (20% of granules), ATP, chromogranins granules), ATP, chromogranins (binding protein), dopamine beta (binding protein), dopamine beta hidroxylase, enkephalinshidroxylase, enkephalins

��Well develop golgi comp., some Well develop golgi comp., some RER, numerous mitochondriaRER, numerous mitochondria

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•• Enclosed in Conn. Tissue Enclosed in Conn. Tissue

capsulecapsule22

•• Consist of :Consist of :22

A.A. Follicles Follicles

B.B. ColloidColloid �� a gelatinous a gelatinous

material inside folliclematerial inside follicle

• Follicle :2

�� Spherical structure, vary in Spherical structure, vary in

diameterdiameter

�� Walls Walls �������� Simple squamous Simple squamous

epitheliumepithelium29

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Transverse section (T: trachea,

Tg: thyroid gland,

Pg: parathyroid gland,

E: esophagus).

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• Principal (follicular) cells:2

��Mainly form wall of follicleMainly form wall of follicle

��Squamous to cuboidal or collumnar, Squamous to cuboidal or collumnar, depend on activity of thyroiddepend on activity of thyroid

��Round to ovoid nuclei, centrally Round to ovoid nuclei, centrally placed, 2 nucleoliplaced, 2 nucleoli

��Numerous small vesicles contain Numerous small vesicles contain thyroglobulinthyroglobulin

��In great demand of thyroid hormone, In great demand of thyroid hormone, follicular cells extend pseudopods follicular cells extend pseudopods into follicles into follicles �� to envelop & absorb to envelop & absorb colloid colloid

��Synthesized ThyroglobulinSynthesized Thyroglobulin

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• Parafollicular / C cells:2, 3

��Present in follicular epith. Present in follicular epith. in conn. Tissue between in conn. Tissue between folliclesfollicles

��2 or 3 times bigger than 2 or 3 times bigger than follicular cells follicular cells

��Occur singly or groupOccur singly or group

��Pale cytoplasm, round Pale cytoplasm, round nucleus, moderate RER, nucleus, moderate RER, elongated mitochondriaelongated mitochondria

��Dense secretory granules Dense secretory granules contain calcitonin contain calcitonin (Thyrocalcitonin) (Thyrocalcitonin)

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•• Structure :Structure :22

��Surrounded by thin conn. tissue capsule Surrounded by thin conn. tissue capsule

�� trabeculae/septa with blood trabeculae/septa with blood

vessels,lymphatics & nervevessels,lymphatics & nerve

��Parenchymal consist of epithelial cells Parenchymal consist of epithelial cells

�� 2 types of cells2 types of cells

•• Contain 2 types of cells :Contain 2 types of cells :

1. Chief (principal) cells1. Chief (principal) cells

2. Oxyphil cells2. Oxyphil cells

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1. Chief (principal) cells :2, 3

�� More numerousMore numerous

�� Slightly eosinophilicSlightly eosinophilic--stainningstainning

�� Contain granules Contain granules

�� Round & centrally placed Round & centrally placed

vesicular nucleivesicular nuclei

�� Juxtanuclear golgi complex, Juxtanuclear golgi complex,

elongated mitochondria, elongated mitochondria,

abundant RERabundant RER

�� PreProparathyroid hormone PreProparathyroid hormone

synthesize on ribosomes of RERsynthesize on ribosomes of RER��

on golgi complex become on golgi complex become

parathyroid hormone parathyroid hormone

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2. Oxyphil cells :2, 3

�� Only small part of cell Only small part of cell

populationspopulations

�� Occur singly or in group Occur singly or in group

�� Larger than chief cellsLarger than chief cells

�� Cytoplasm stains intensely Cytoplasm stains intensely

with eosin (acidophil)with eosin (acidophil)

�� More mitochondria, smaller More mitochondria, smaller

golgi app. & little RERgolgi app. & little RER

�� Intermediate cells Intermediate cells �� in in

active phase of chief cells active phase of chief cells

�� Function unknown Function unknown

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•• Cover by thin conn. tissue capsule Cover by thin conn. tissue capsule �� continous with meningeal continous with meningeal (pial) tissue (pial) tissue �� septasepta1, 21, 2

• 2 types of cells :1, 2, 3

1. Pinealocytes1. Pinealocytes

2. Glial / Intertitial cells2. Glial / Intertitial cells

A. Pinealocytes

–– Basophilic cells Basophilic cells 2, 32, 3

–– Large lobulated nuclei Large lobulated nuclei 1, 21, 2

–– Produce melatonin & several other subtances Produce melatonin & several other subtances

B. Glial / intertitial cells :1, 2

��Fewer number than pinealocytes Fewer number than pinealocytes

��Nuclei smaller & stain more deeplyNuclei smaller & stain more deeply

��Long cytoplasmic process, regarded as a form of astrocyteLong cytoplasmic process, regarded as a form of astrocyte

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• Corpora adranacea (brain sand) :1, 2

��Concretions found in pineal gland of humansConcretions found in pineal gland of humans

��Irregularly shaped structures occur in capsule & Irregularly shaped structures occur in capsule &

substance of glandsubstance of gland

��Consist mainly calcium carbonate & phosphatesConsist mainly calcium carbonate & phosphates

��Increased with age, function unknownIncreased with age, function unknown

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• Pancreatic islets : 2

�� Scattered among pancreatic Scattered among pancreatic aciniacini

�� Irregular, elongate masses of Irregular, elongate masses of pale pale stainningstainning cellscells

�� In ordinary sections In ordinary sections ��homogenous population of homogenous population of pale polygonal cellpale polygonal cell22

�� In elect. Micrograph & special In elect. Micrograph & special stainningstainning ::22

1.1. Alpha / A cellsAlpha / A cells

2.2. Beta / B cellsBeta / B cells

3.3. Delta / D cellsDelta / D cells

4.4. PP cellsPP cells

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1. Alpha cells : 2

�� 20% of islet cells 20% of islet cells

�� Periphery of isletsPeriphery of islets

�� Contain large, dense, Contain large, dense, spherical granulesspherical granules

2. Beta cells :2

�� 78% of islet cells78% of islet cells

�� Locate near the center of Locate near the center of isletsislets

�� SecretorySecretory granules smaller granules smaller than alpha cells, contain than alpha cells, contain small, dense crystals small, dense crystals

3. Delta & PP cells located periphery of islets2

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CELL TYPES CELL TYPES HORMONAL HORMONAL

SUBSTANCESSUBSTANCES

PRIMARY PRIMARY

FUNCTIONFUNCTION

A (alpha) A (alpha) GlucagonGlucagon Increase blood sugarIncrease blood sugar

B (beta)B (beta) Insulin Insulin Decrease blood Decrease blood

sugarsugar

D (delta)D (delta) SomatostatinSomatostatin Inhibitor of hormone Inhibitor of hormone

secretions secretions

PP PP Pancreatic Pancreatic

PolypeptidePolypeptide

Opposes action of Opposes action of

cholecystokinincholecystokinin

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1.1. Basic Histology Text & Atlas Basic Histology Text & Atlas , , 10th ed. 10th ed. , L. Carlos Junquira , L. Carlos Junquira MD, Jose Carneiro MD, Robert O. Kelley PhD, MD, Jose Carneiro MD, Robert O. Kelley PhD, Lange Lange

Medical Books, Mc GrawMedical Books, Mc Graw--Hill Hill , 1995. Pp 403 , 1995. Pp 403 –– 430. 430.

2.2. Essentials of Human Histology, 2Essentials of Human Histology, 2ndnd Edition, William Edition, William J. Krausse PhD, Little Brown & Company (Inc), 1996. J. Krausse PhD, Little Brown & Company (Inc), 1996. Pp 377Pp 377--392392

3.3. Color Textbook of Histologi, 2Color Textbook of Histologi, 2ndnd edition, Gartner LP, edition, Gartner LP, Hiatt JL, WB Saunders Company, Philadelphia, Hiatt JL, WB Saunders Company, Philadelphia, Pennsylvania, 2001. Pp 301Pennsylvania, 2001. Pp 301--324324

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