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Endocrine System 李立仁 副教授 解剖學暨細胞生物學科 基醫大樓六樓 617室 [email protected] Endocrine glands - Ductless - Rich vascular supply - Fenestrated capillaries TutorVista.com Pituitary gland www.vivo.colostate.edu/.../hypopit/sagpitbig.jpg www.vivo.colostate.edu/.../hy popit/sagpitbig.jpg Glandular epithelial tissue (anterior lobe, adenohypophysis) Pituitary gland www.vivo.colostate.edu/.../hy popit/sagpitbig.jpg Neural secretary tissue (posterior lobe, neurohypophysis) Pituitary gland Development Pituitary gland Pituitary gland Blood supply Hypothalamic neurons Nerve ending in median eminence primary capillary network Hypothalmohypophyseal portal circulation (portal vein) Secondary capillary network in adenohypophysis Anterior lobe of pituitary gland Three subdivisions: Pars distalis Pars intermedia Pars tuberalis (pars infundibularis) Secret: Growth hormone (somatotropes) Prolactin (lacto/mammotropes) ACTH (corticotropes) FSH, LH (gonadotropes) TSH (thyrotropes) Pars Distalis Anterior lobe of pituitary gland Cell Cord / sinusoids (capillaries) Chromophils ( ) and Chromophobes ( ) Pars Distalis Anterior lobe of pituitary gland Classification of cell types Histochemical features: Basophils (15%), acidophils (35%) and chromophobes (50%), or periodic-acid-Schiff reagent (PAS) for glycoproteins Immunocytochemical features: Specific antibody to each hormone or key molecule EM features: Size/shape of granules, cell shape, organelles, nuclear features Pars Distalis Anterior lobe of pituitary gland HE: acidophils (red), basophils (blue), chromophobes Pars Distalis Anterior lobe of pituitary gland Cell types Acidophils (35%): Somatotrope (GH), Lactotrope/Mammotrope (prolactin, PRL) Basophils (15%): Corticotropes (ACTH), Gonadotrope (FSH, LH), Thyrotrope (TSH), Chromophobes (50%): Cells without secretory granules (follicular cells, stellate cells) and/or degranulated cells Pars Distalis Anterior lobe of pituitary gland Immunohistochemistry Cells in the sections Rabbit anti-LH Ab Peroxidase-goat anti-rabbit IgG Substrate reaction Immunohistochemistry for LH Pars Distalis Somatotropes Acidophilic Densely packed granules (350 nm) Produce growth hormone (somatotropin) Enhance body growth - dwarfism - gigantism - acromegaly Stimulated by exercise 17-14 Pars Distalis Lactotropes Acidophilic Small granules (200 nm) at rest and enlarged (600 nm) during pregnancy and lactation Produce prolactin Promote mammary development and lactation 17-15 Pars Distalis Corticotrope Basophilc Granules of variable size (100-300 nm) Produce ACTH and related peptides 17-16 Pars Distalis Gonadotrope Basophilc Granules of intermediate size (200-250 nm) and varied electron density Produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH) 17-17 Pars Distalis Thyrotropes Basophilc Small granules (<150 nm) Produce thyroidstimulating hormone Stimulates thyroid functions Feedback regulated by thyroid function 17-18 Pars Distalis Anterior lobe of pituitary gland Pars Intermedia Anterior lobe of pituitary gland Intermediate lobe Contains basophils and chromophobes Basophils extend into pars nervosa Unclear function in humans Isamine blue/eosin Anterior lobe of pituitary gland Pars tuberalis Highly vascular Clusters of basophils (ACTH, LH, FSH) www.vivo.colostate.edu/.../pitgranules.jpg Posterior lobe of pituitary gland Three subdivisions: Median eminence Infundibular stem Pars nervosa Secret: Oxytocin Vasopressin (ADH) 17-22 Pars nervosa Posterior lobe of pituitary gland Posterior lobe of pituitary gland Pituicytes (neuroglial cells): irregular cell shape with many branches, oval nucleus, possess glial fibrillar acidic protein (GFAP) intermediate filaments Unmyelinated nerve fibers Axons containing neurosecretory granules Fenestrated capillaries Fibroblasts, mast cells Pars nervosa Posterior lobe of pituitary gland Nerve fibers Pituicytes Neurosecretory granules Axons from supraoptic and paraventricular nuclei form the hypothalamo-hypophyseal tract. Neurosecretory granules (Herring bodies) contain oxytocin, vasopressin (ADH), and carrier proteins. Pars nervosa Posterior lobe of pituitary gland Pituicytes Secretions are released to fenestrated capillary ( ) via exocytosis. Oxytocin and ADH neurons Pars nervosa Posterior lobe of pituitary gland Herring bodies The dilated portions of the axons due to the accumulation of secretory granules. Pars nervosa Fenestrated capillary Posterior lobe of pituitary gland Pineal gland Also called epiphysis or the "third eye" Covered by pia mater (CT)) Septa----lobulation----lobules Parenchyma 1. Pinealocytes 2. Glial cells (interstitial cells) 3. Brain sand (corpora arenacea) Pineal gland H&E Pineal gland Cell types Pinealocytes: 95% cell ratio, large pale cells with well developed rER, sER, Golgi apparatus, mitochondria, expanded, club-like (bulbous) ending associated with capillaries Neuroglial cells (interstitial cells): 5% cell ratio, dark stellate cells with long cell processes Pineal gland Pinealocytes have bulbous expansions Pineal gland Brain sand (corpora arenacea) Recognizable in childhood and increase in number with age X-ray opaque, as midline marker in radiograpophic and computer tomography studies Precipitations of calcium phosphates and carbonates on carrier proteins Goals of this class 1. Understand the differences between endocrine and exocrine glands. 2. Recognize sinusoids and cell cords in the anterior pituitary gland. 3. Indentify acidophils, basophils and chromophobes in H&E stained sections of ant. p-gland. 4. Appreciate the cytoarchetecture of the post. p-gland. 5. Know the features of herring bodies in post. p-gland. 6. Comprehend the histological organization of the pineal gland. Thyroid gland Capsule - septa - lobules Thyroid follicles Follicular lumen containing colloids (thyroglobulin/T3, T4) Parafollicular cells (C cells): Calcitonin, lowers circulating Ca2+ levels Fenestrated capillaries Thyroid gland Lobulation Thyroid gland Follicles Capillary network around the follicles Thyroid gland Follicular cells Synthesis and Secretion of T3 and T4 Thyroglobulin/rER Iodine peroxidation Iodinated thyroglobulin stored in the follicular lumen Endocytosis Lysosomal action Release of T3, T4 into blood capillaries Follicular cells Thyroid gland Inactive Active Thyroid gland Parafollicular cells (C cells) Parafollicular cells (C cells) Thyroid gland Parafollicular cells (C cells) Calcitonin – lowering by Ca2+ levels by stimulating osteoblasts to take Ca2+ out of the circulation and inhibiting the bone resorption by osteoclasts. instruction.cvhs.okstate.edu/.../hrendo7.jpg Parathyroid gland Capsule - septa - anastomosing cell cords Principal (chief) cells: Product PTH that elevates blood Ca2+ level Oxyphil cells: large cells with many mitochondria (esoinophilia) Parathyroid gland http://www.nku.edu/~dempseyd/THE_ENDOCRINE5.htm 17-45 Parathyroid gland Principal (chief) cells Oxyphil cells Oxyphil cells 17-46 Principle (chief) cells Oxyphil cells pathology.mc.duke.edu Principal (chief) cells Parathyroid gland Principal (chief) cells Parathyroid gland PTH -- elevates blood Ca2+ level by promoting Ca2+ release from bone (activate osteoclasts) and Ca2+ reabsorption from kidney and intestine. instruction.cvhs.okstate.edu/.../hrendo7.jpg Principal (chief) cells Parathyroid gland Oxyphil cells Parathyroid gland Goals of this class 1. Note the cytoarchetecture of the thyroid and parathyroid glands. 2. Identify follicular and parafollicular cells in the thyroid gland 3. Characterize chief cells and oxyphil cells in H&E stained sections of parathyroid gland. 17-51 Adrenal gland Blood supply Cortex Zona glomerulosa (15%) Zona fasculata (80%) Zona reticularis (5%) Medulla Chromaffin cells Ganglion cells Adrenal gland Adrenal gland Blood circulation Suprarenal arteries Subcapsular plexus Short cortical arterioles Cortical sinusoidal system Sinusoidal system in medulla Central vein Adrenal gland Blood circulation Suprarenal arteries Subcapsular plexus Long cortical arterioles Capillary networks in medulla Central vein Cortex Adrenal gland Zona glomerulosa Upper zone Columnar cells arranged as balls Acidophilic cytoplasm: sER, mitochondria with tubular cristae Secrete mineralocorticoids (aldosterone) Cortex Steroidogenic cells Mitochondria with tubular cristae Adrenal gland Cortex Adrenal gland Zona fasciculata Cells arranged into long straight columns Secrete glucocorticoids Spongiocytes Cytoplasm containing many mitochondria, sER and lipid droplets Zona fasciculata Adrenal gland Spongiocytes in zona fasciculata Reticular fiber staining Zona fasciculata Adrenal gland Adrenal cortex Zona reticularis Cell cords in anastomosing network (anatomosing sinusoids) Secrete glucocorticoids and androgens Acidophilic cytoplasm: Lipid droplets, mitochondria, rER, lipofuscin (lipofuchsin) pigments Zona reticularis Adrenal gland Development Adrenal gland Fetal adrenal gland Medulla Adrenal gland Adrenal medulla Adrenal cortex Adrenal medulla Medulla Adrenal gland Medulla Adrenal gland Cell types Glandular (chromaffin) cells: Modified postganglionic neurons Innervated by preganglionic sympathetic fibers Contain catecholamine granules reacted with chrome solution --- brown granules Fenestrated capillaries Medulla Adrenal gland Zona reticularis Chromaffin cells Medulla Adrenal gland Chromaffin cells Medulla Adrenal gland Chromaffin cells Medulla Ganglionic cells Adrenal gland Postganglionic neurons that innervate blood vessels Medulla Adrenal gland Ganglionic cells reference.findtarget.com Adrenal gland Goals of this class 1. Know the origins adrenal cortex and medulla. 2. Discern the pathways of blood supply in the adrenal gland. 3. Know the features of steroidogenic cells. 4. Identify the cortex and medulla of adrenal gland based on their histological characteristics. 5. Recognize the zones in adrenal cortex. 6. Distinguish the cell types in the adrenal medulla.