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  • Endocrine system regulates metabolic activities help in bring out homeostasis3Nervous & endocrine systems functions in different way interact to modulate & coordinate metabolic activities of body3Secretory products/hormones secreted into:1, 2Blood or lymphatic circulation Directly into intercellular spaceRich in vascular supply, secreting cells direct access to cappilllaries2

  • DUCTLESS GLANDS (pituitary gland/hypophysis, adrenal gland, parathyroid gland, thyroid gland, pineal gland)2, 3UNICELLULAR ENDOCRINE CELLS form a diffuse endocrine system (e. g: In GI tract, conducting airways of lung)2, 3

  • TestesOvariesClassic Endocrine Glands

  • Lying in sella turcica2Produces hormones responsible for regulating growth, reproduction & metabolism3Hypophysis subdivision :1, 2, 3ADENOHYPOPHYSIS (anterior pituitary) epithelial component :- Pars distalis anterior lobe- Pars intermedia- Pars tuberalis NEUROHYPOPHYSIS (posterior pituitary) nervous component :- Pars nervosa (major part)- Infundibular stalk- Median eminence Posterior lobe Pars intermedia + pars nervosa 2

  • Figure 18.6a, b

  • 75% of hypophysis1Composed of cords of cells with large sinusoidal cappilaries3 Endothelial lining of sinusoids fenestrated fascilitates diffusion of releasing factors & provides entry sites for secretions32 kind of cells base on affinity for dyes :1, 2, 31. Chromophobic cells2. Chromophilic cells :- Acidophilic cells- Basophilic cells

  • Most abundant cells in pars distalis3Structure :2, 3Large, round or ovoid cellsLage secretory granules stain orange to red with eosin2 KIND OF CELLS

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

  • Secretory granules stain blue with basic dye3Located at periphery of pars distalis3Consist of 3 types of cells :2, 3

  • Small, No granules2Less cytoplasm than chromophils Fail to color with routine stains2, 3Degranulated chromophilicA reservoir of chromophilic cells2

  • Non secretory, star shape cellsConstitute large population of pars distalisHave long processes form gap junctionFunction not clear

  • Forms a sleeve, around infundibular stalk2Longitudinally arranged cords of cuboidal to low collumnar epithelial cells separated by sinusoids1,2, 3Basophilic cytoplasm, small den se granules, with lipid droplets3No spesific hormone secreted 2, 3

  • Rudimentary in humans, only 2% of hypophysis2Consist of :2, 3Chromophobe cellsBasophil cells small granulesColloid-containing cysts lined by chromophobic or basophilic cell (cuboidal cells)Function of cells is unknown1, 2

  • Develops from a downgrowth of hypothalamus Macroscopically consist of :2Median EminenceInfudibular StalkInfundibular Process (pars nervosa)

  • Tecnically not endocrine glands3Hormones synthesized in perikarya of neurons supraoptic & paraventicular nuclei in hypothalamus pass down axon stored in nerve terminals that form pars nervosa2Consist of unmyelinated nerve fibers/axons forms hypothalamo-hypophyseal tract1, 2

  • Axon contain HERRING BODIES accumulation of dense neurosecretory granules2, 3Pituicytes :1, 2, 3Scattered among nerve fibers25% of pars nervosaOnly nuclei stain well enoughVary in size & shapeEquivalent to neuroglial cells of CNS supported axons in pars nervosaHormones stored & released from pars nervosa :2- ADH / Vasopressin- Oxytocin

  • A pair of flattened, triangular struct2, 3Surrounded by thick conn. Tissue capsule forms trabeculaeConsist of adrenal cortex & adrenal medulla2, 3

    A yellow pheripheral layer180-90% of organs3 Parenchyma : continous cords of secretory cells, separated by blood sinusoids2

  • Subdivided into 3 layer :1, 21. Outer zona glomerulosa2. Middle zona Fasciculata3. Inner zona reticularis

    Zona glomerulosa :1, 2, 3A narrow band beneath capsule, 15% of organsSmall Collumnar cells arranged into arcadesSpherical, central nuclei & 1 or 2 nucleoliAcidophilic cytoplasm SER >>, well develop golgi comp., short mitochondria

  • Zona Fasciculata :1, 2Widest zone of cortex 65-80% of organs Polyhedral Cells larger than in other 2 zone arrange in radial collumsSpherical & centrally nuclei, binucleate Cytoplasm with many lipid droplets lipid eliminated during stainningappear vacuolated cells called SPONGIOCYTELipid droplets contain neutral fat, fatty acids, fatty acyl esters of cholesterol precursor for synthesize steroid hormones Spherical mitochondria, extensive SER, some RER, lysosomes

  • Zona Reticularis :1, 2, 37% of organs A network of irregular anastomosing cordsSimilar cells to fasciculata except smallerAcidophilic cytoplasm, contain fewer lipid dropletsNuclei stain more deeply

  • Hormones secreted by :1, 2Zona glomerulosa : mineralcorticoids primarily aldosteroneZona Fasciculata : glucocorticoids cortisone and cortisolZona reticularis : glucocorticoids cortisone and cortisol (probably)Cells of adrenal cortex NOT store secretory products in granules synthesize & secrete steroid hormone only upon demands1

  • Composed of Chromaffin cells & sympathetic ganglionic cells3

    CHROMAFFIN CELLS :1, 2A large round or polyhedral cellsNumerous brown granules treated with chromium salts (chromaffin reaction)Granules may contain epinephrine or norepinephrine (20% of granules), ATP, chromogranins (binding protein), dopamine beta hidroxylase, enkephalinsWell develop golgi comp., some RER, numerous mitochondria

  • Enclosed in Conn. Tissue capsule2Consist of :2Follicles Colloid a gelatinous material inside follicle

    Follicle :2Spherical structure, vary in diameterWalls Simple squamous epithelium

  • Principal (follicular) cells:2Mainly form wall of follicleSquamous to cuboidal or collumnar, depend on activity of thyroidRound to ovoid nuclei, centrally placed, 2 nucleoliNumerous small vesicles contain thyroglobulinIn great demand of thyroid hormone, follicular cells extend pseudopods into follicles to envelop & absorb colloid Synthesized Thyroglobulin

  • Parafollicular / C cells:2, 3Present in follicular epith. in conn. Tissue between follicles2 or 3 times bigger than follicular cells Occur singly or groupPale cytoplasm, round nucleus, moderate RER, elongated mitochondriaDense secretory granules contain calcitonin (Thyrocalcitonin)

  • Structure :2Surrounded by thin conn. tissue capsule trabeculae/septa with blood vessels,lymphatics & nerveParenchymal consist of epithelial cells 2 types of cellsContain 2 types of cells :1. Chief (principal) cells2. Oxyphil cells

  • Chief (principal) cells :2, 3More numerousSlightly eosinophilic-stainningContain granules Round & centrally placed vesicular nucleiJuxtanuclear golgi complex, elongated mitochondria, abundant RERPreProparathyroid hormone synthesize on ribosomes of RER on golgi complex become parathyroid hormone

  • Oxyphil cells :2, 3Only small part of cell populationsOccur singly or in group Larger than chief cellsCytoplasm stains intensely with eosin (acidophil)More mitochondria, smaller golgi app. & little RERIntermediate cells in active phase of chief cells Function unknown

  • Cover by thin conn. tissue capsule continous with meningeal (pial) tissue septa1, 22 types of cells :1, 2, 31. Pinealocytes2. Glial / Intertitial cells

    Pinealocytes Basophilic cells 2, 3Large lobu


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