Classic Endocrine Glands

Transcription

1 1 Endocrine system regulates metabolic activities help in bring out homeostasis 3 Nervous & endocrine systems functions in different way interact to modulate & coordinate metabolic activities of body 3 Secretory products/hormones secreted into: 1, 2 Blood or lymphatic circulation Directly into intercellular space Rich in vascular supply, secreting cells direct access to cappilllaries 2 2 1

2 3 1. DUCTLESS GLANDS (pituitary gland/hypophysis, adrenal gland, parathyroid gland, thyroid gland, pineal gland) 2, 3 2. UNICELLULAR ENDOCRINE CELLS form a diffuse endocrine system (e. g: In GI tract, conducting airways of lung) 2, 3 4 2

3 Classic Endocrine Glands Ovaries Testes 5 6 3

4 Lying in sella turcica 2 Produces hormones responsible for regulating growth, reproduction & metabolism 3 Hypophysis subdivision : 1, 2, 3 A. ADENOHYPOPHYSIS (anterior pituitary) epithelial component : -Pars distalis anterior lobe - Pars intermedia -Pars tuberalis B. NEUROHYPOPHYSIS (posterior pituitary) nervous component : - Pars nervosa (major part) - Infundibular stalk -Median eminence Posterior lobe Pars intermedia + pars nervosa

5 9 Figure 18.6a, b 75% of hypophysis 1 Composed of cords of cells with large sinusoidal cappilaries 3 Endothelial lining of sinusoids fenestrated fascilitates diffusion of releasing factors & provides entry sites for secretions 3 2 kind of cells base on affinity for dyes : 1, 2, 3 1. Chromophobic cells 2. Chromophilic cells : - Acidophilic cells - Basophilic cells 10 5

6 Secretory granules stain with histological dyes stain with acid dyes or stain with basic dyes 3 Most abundant cells in pars distalis 3 Structure : 2, 3 Large, round or ovoid cells Lage secretory granules stain orange to red with eosin 2 KIND OF CELLS 11 o Secretory granules stain blue with basic dye 3 o Located at periphery of pars distalis 3 o Consist of 3 types of cells : 2,

7 Small, No granules 2 Less cytoplasm than chromophils Fail to color with routine stains 2, 3 Degranulated chromophilic A reservoir of chromophilic cells 2 13 Non secretory, star shape cells Constitute large population of pars distalis Have long processes form gap junction Function not clear 14 7

8 Chromophilic cells Acidophilic cells Basophilic cells Somatotrope cells Mammotrope cells Corticotropes cells Thyrotropes cells Gonadotropes cells Chromophobe cells FSH secreting cells LH secreting cells Folliculostellate cells 15 Forms a sleeve, around infundibular stalk 2 Longitudinally arranged cords of cuboidal to low collumnar epithelial cells separated by sinusoids 1,2, 3 Basophilic cytoplasm, small den se granules, with lipid droplets 3 No spesific hormone secreted 2,

9 Rudimentary in humans, only 2% of hypophysis 2 Consist of : 2, 3 1. Chromophobe cells 2. Basophil cells small granules 3. Colloid-containing cysts lined by chromophobic or basophilic cell (cuboidal cells) Function of cells is unknown 1, 2 17 Develops from a downgrowth of hypothalamus Macroscopically consist of : 2 1. Median Eminence 2. Infudibular Stalk 3. Infundibular Process (pars nervosa) 18 9

10 Tecnically not endocrine glands 3 Hormones synthesized in perikaryaof neurons supraoptic & paraventicularnuclei nuclei in hypothalamus pass down axon stored in nerve terminals that form pars nervosa 2 Consist of unmyelinatednerve nerve fibers/axons forms hypothalamo-hypophysealhypophyseal tract 1, 2 19 Axon contain HERRING BODIES accumulation of dense neurosecretory granules 2, 3 Pituicytes : 1, 2, 3 Scattered among nerve fibers 25% of pars nervosa Only nuclei stain well enough Vary in size & shape Equivalent to neuroglial cells of CNS supported axons in pars nervosa Hormones stored & released from pars nervosa : 2 - ADH / Vasopressin -Oxytocin 20 10

11 21 A pair of flattened, triangular struct 2, 3 Surrounded by thick conn. Tissue capsule forms trabeculae Consist of adrenal cortex & adrenal medulla 2, 3 A yellow pheripheral layer % of organs 3 Parenchyma : continous cords of secretory cells, separated by blood sinusoids

12 23 Subdivided into 3 layer: 1, 2 1. Outer zona glomerulosa 2. Middle zona Fasciculata 3. Inner zona reticularis 1. Zona glomerulosa: 1, 2, 3 A narrow band beneath capsule, 15% of organs Small Collumnar cells arranged into arcades Spherical, central nuclei & 1 or 2 nucleoli Acidophilic cytoplasm SER >>, well develop golgi comp., short mitochondria 24 12

13 2. Zona Fasciculata : 1, 2 Widest zone of cortex 65-80% of organs Polyhedral Cells larger than in other 2 zone arrange in radial collums Spherical & centrally nuclei, binucleate Cytoplasm with many lipid droplets lipid eliminated during stainning appear appear vacuolated cells called SPONGIOCYTE Lipid 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, 3 7% of organs A A network of irregular anastomosing cords Similar cells to fasciculata except smaller Acidophilic cytoplasm, contain fewer lipid droplets Nuclei stain more deeply 26 13

14 Hormones secreted by : 1, 2 1.Zona glomerulosa : mineralcorticoids primarily aldosterone 2.Zona Fasciculata : glucocorticoids cortisone and cortisol 3.Zona reticularis : glucocorticoids cortisone and cortisol (probably) Cells of adrenal cortex NOT store secretory products in granules synthesize & secrete steroid hormone only upon demands 1 27 Composed of Chromaffin cells & sympathetic ganglionic cells 3 CHROMAFFIN CELLS: 1, 2 A A large round or polyhedral cells Numerous brown granules treated with chromium salts (chromaffin reaction) Granules may contain epinephrine or norepinephrine (20% of granules), ATP, chromogranins (binding protein), dopamine beta hidroxylase, enkephalins Well develop golgi comp., some RER, numerous mitochondria 28 14

15 Enclosed in Conn. Tissue capsule 2 Consist of : 2 A. Follicles B. Colloid a gelatinous material inside follicle Follicle : 2 Spherical structure, vary in diameter Walls Simple squamous epithelium 29 Transverse section (T: trachea, Tg: thyroid gland, Pg: parathyroid gland, E: esophagus)

16 Principal (follicular) cells: 2 Mainly form wall of follicle Squamous to cuboidal or collumnar, depend on activity of thyroid Round to ovoid nuclei, centrally placed, 2 nucleoli Numerous small vesicles contain thyroglobulin In great demand of thyroid hormone, follicular cells extend pseudopods into follicles to envelop & absorb colloid Synthesized Thyroglobulin

17 Parafollicular / C cells: 2, 3 Present in follicular epith. in conn. Tissue between follicles 2 2 or 3 times bigger than follicular cells Occur singly or group Pale cytoplasm, round nucleus, moderate RER, elongated mitochondria Dense secretory granules contain calcitonin (Thyrocalcitonin) 33 Structure : 2 Surrounded by thin conn. tissue capsule trabeculae/septa with blood vessels,lymphatics & nerve Parenchymal consist of epithelial cells 2 2 types of cells Contain 2 types of cells : 1. Chief (principal) cells 2. Oxyphil cells 34 17

18 35 1. Chief (principal) cells : 2, 3 More numerous Slightly eosinophilic-stainningstainning Contain granules Round & centrally placed vesicular nuclei Juxtanuclear golgi complex, elongated mitochondria, abundant RER PreProparathyroid hormone synthesize on ribosomes of RER on golgi complex become parathyroid hormone 36 18

19 2. Oxyphil cells : 2, 3 Only small part of cell populations Occur singly or in group Larger than chief cells Cytoplasm stains intensely with eosin (acidophil) More mitochondria, smaller golgi app. & little RER Intermediate cells in active phase of chief cells Function unknown 37 Cover by thin conn. tissue capsule continous with meningeal (pial) tissue septa 1, 2 2 types of cells : 1, 2, 3 1. Pinealocytes 2. Glial / Intertitial cells A. Pinealocytes Basophilic cells 2, 3 Large lobulated nuclei 1, 2 Produce melatonin & several other subtances B. Glial / intertitial cells: 1, 2 Fewer number than pinealocytes Nuclei smaller & stain more deeply Long cytoplasmic process, regarded as a form of astrocyte 38 19

20 Corpora adranacea (brain sand) : 1, 2 Concretions found in pineal gland of humans Irregularly shaped structures occur in capsule & substance of gland Consist mainly calcium carbonate & phosphates Increased with age, function unknown

21 Pancreatic islets : 2 Scattered among pancreatic acini Irregular, elongate masses of pale stainning cells In ordinary sections homogenous population of pale polygonal cell 2 In elect. Micrograph & special stainning: 2 1. Alpha / A cells 2. Beta / B cells 3. Delta / D cells 4. PP cells Alpha cells : 2 20% of islet cells Periphery of islets Contain large, dense, spherical granules 2. Beta cells : 2 78% of islet cells Locate near the center of islets Secretorygranules smaller than alpha cells, contain small, dense crystals 3. Delta & PP cells located periphery of islets

22 CELL TYPES A (alpha) B (beta) D (delta) PP HORMONAL SUBSTANCES Glucagon Insulin Somatostatin Pancreatic Polypeptide PRIMARY FUNCTION Increase blood sugar Decrease blood sugar Inhibitor of hormone secretions Opposes action of cholecystokinin Basic Histology Text & Atlas, 10th ed., L. Carlos Junquira MD, Jose Carneiro MD, Robert O. Kelley PhD, Lange Medical Books, Mc Graw-Hill, Pp Essentials of Human Histology, 2 nd Edition, William J. Krausse PhD, Little Brown & Company (Inc), Pp Color Textbook of Histologi, 2 nd edition, Gartner LP, Hiatt JL, WB Saunders Company, Philadelphia, Pennsylvania, Pp