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THYROID GLAND, PARATHYROID GLAND, ADRENAL GLAND, PINEAL GLAND, PANCREAS Dr. Anna L. Kiss

THYROID GLAND, PARATHYROID GLAND, ADRENAL GLAND, PINEAL GLAND, PANCREAS Dr. Anna L. Kiss Semmelweis University Department of Anatomy, Histology and Embryology 2018. ENDOCRINE GLANDS. Pineal gland. Hypophysis. Parathyroid gland. Thyroid gland. Adrenal gland. Endocrine pancreas. Gonads.

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THYROID GLAND, PARATHYROID GLAND, ADRENAL GLAND, PINEAL GLAND, PANCREAS Dr. Anna L. Kiss

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  1. THYROID GLAND, PARATHYROID GLAND, ADRENAL GLAND, PINEAL GLAND, PANCREAS Dr. Anna L. Kiss Semmelweis University Department of Anatomy, Histology and Embryology 2018

  2. ENDOCRINE GLANDS Pineal gland Hypophysis Parathyroid gland Thyroid gland Adrenal gland Endocrine pancreas Gonads

  3. ENDOKRIN MIRIGYEK 1.) Directed by the hypothalamo-hypophyseal system: thyroid gland adrenal cortex gonads 2.) NOT directed by the hypothalamo-hypophyseal system: parathyroid adrenal medulla Langerhans islands corpus pineale

  4. THYROID GLAND anatomy Larynx Lobes Isthmus Trachea

  5. THYROID GLAND anatomy It develops behind the buccopharyngeal membrane from the thyroglossal duct + neural crest cells Pyramidal lobe (~40%) Lobes Isthmus

  6. THYROID GLAND histology Capsule: outer loose connective tissue inner fibroelastic tissue Connective tissue septa: irregular lobules Parenchyma: follicles: spheres (0.2-1 mm in diameter) simple epithelium on basal lamina: follicular cells central colloid core parafollicular cells (C cells) Stroma: loose connective tissue with: dense plexus of fenestrated capillaries lymphatic vessels symphathetic nerve fibers

  7. THYROID GLAND histology Follicular cells: from low cuboidal to columnar depending on the functional state round nucleus, prominent nucleolus basophilic cytoplasm: basal rER supranuclear Golgi apparatus apical small secretory vesicles apical endosomes: colloidal resorption droplets lysosomes apical microvilli Colloid: thyroglobulin: - is an iodinated glycoprotein (660 kDa) ~120 tyrosine residues inactively stored thyroid hormones Thyroid hormones: iodinated amino acid derivatives (tyrosine)

  8. THYROID GLAND histology Thyroid hormone synthesis: 1. synthesis of thyroglobulin and thyroperoxidase in rER, modification in Golgi, secretion on the apical plasma membrane 2. uptake of iodide from blood on the basal plasma membrane (Na+/J- symporter); secretion on the apical membrane (J-/Cl- transporter) oxydation of iodide to iodine (thyroperoxidase!) in the colloid 3. iodination of thyroglobulin: monoiodotyrosine (MIT) and diiodotyrosine (DIT) formation 4. triiodothyronine (T3) and thyroxine (T4) formation 5. resorption of colloid; vesicles fused with lysosomes 6. release of T3 and T4 into blood

  9. THYROID GLAND histology Septum Capsule

  10. THYROID GLAND histology Microvilli Follicular cell Colloid Site of thyroglobulin resorption

  11. THYROID GLAND function Role of thyroid hormones: critical for normal growth and development increase of basal metabolic rate Regulation of thyroid hormone secretion: by hypothalamo-hypophyseal TRH-TSH system Hypothyreodism: infancy, early childhood: impaired growth and CNS development – Cretenism adult: slowing of physical and mental activity – Myxedema

  12. Hypothyreosis: infancy, early childhood: - dwarfism - cretenism adult: physical and mental slowing down goiter (hypofunctional: connective tissue!) myxoedema

  13. THYROID GLAND function Hyperthyreodism: Basedow disease hypermetabolic state exoftalmus goiter

  14. THYROID GLAND-PARAFOLLICULAR CELLS Parafollicularcells (C cells): located: • in theperiphery of follicles: withinthebasallamina neverreachthe lumen • in clusters in theinterfollicularstroma pale-stainingcytoplasm(C forclear): prominentGolgi apparatus smallsecretoryvesicles secretecalcitonin: 32-amino acidpolypeptide

  15. THYROID GLAND-PARAFOLLICULAR CELLS histology Parafollicular cell Follicular cell Colloid

  16. THYROID GLAND-PARAFOLLICULAR CELLS histology Parafollicular cells

  17. THYROID GLAND-PARAFOLLICULAR CELLS function Role of calcitonin: decreases blood calcium level: ↓ Ca2+ resorption from the bone ↑ calcium deposition into bones Regulation of calcitonin secretion: by blood calcium level hypophysis-independent No clinical symptoms

  18. PARATHYROID GLAND anatomy Pharynx Thyroid gland Parathyroid glands Oesophagus

  19. PARATHYROID GLAND anatomy Shape: ovoid or lenticular Colour: yellowish-brown Position: behind the posterior lobar border of thyroid gland, within the capsule Dimensions: length: 3-6 mm width: 2-4 mm thickness: 1-2 mm Weight: 0.1-0.2 g

  20. PARATHYROID GLAND histology Capsule: thin connective tissue Connective tissue septa: poorly defined lobules Parenchyma: cords of epithelial cells: principal (chief) cells oxyphil cells Stroma: loose connective tissue with: dense plexus of fenestrated capillaries lymphatic vessels adipose tissue increases till adulthood (up to 30%)

  21. PARATHYROID GLAND histology Principal (chief cells): predominant cell type small polygonal cells large spherical nucleus pale, slightly eosinophilic cytoplasm (activity dependent): Golgi apparatus in active cells small secretory vesicles in active cells glycogen in inactive cells lipid droplets lipofuscin granules secrete parathormone (PTH): 84-amino acidpolypeptide

  22. PARATHYROID GLAND histology Oxyphil cells: minor cell population, singly or in clusters large rounded cells smaller darker nucleus acidophilic cytoplasm: large number of mitochondria no secretory vesicles little rER produce?

  23. PARATHYROID GLAND histology Septum Adipose tissue Capsule

  24. PARATHYROID GLAND histology Oxyphil cell Principal cell (inactive) Principal cell (active)

  25. PARATHYROID GLAND function Role of parathormone (PTH): increases blood calcium level: ↑ bone resorption ↑ calcium reabsorption in kidneys ↑ formation of active vitamine D3 ↑ intestinal absorption of calcium decreases blood phosphate level: ↑ phosphate excretion in kidneys Regulation of parathormone secretion: by blood calcium level hypophysis-independent

  26. PARATHYROID GLAND function Hypoparathyroidism: hypocalcemia → tetany Hyperparathyroidism: hypercalcemia, osteoporosis

  27. ADRENAL GLAND anatomy Right adrenal gland Left adrenal gland

  28. ADRENAL GLAND anatomy Shape: right: pyramidal left: semilunar Colour: golden yellow Position: superior and slightly anterior to the kidneys left adrenal gland is more inferior

  29. ADRENAL GLAND histology Capsule: thick, dense irregular connective tissue Delicate connective tissue trabecules Parenchyma: cortex: constitutes 90% of adrenal weight yellowish in colour secretion of steroid hormones medulla: constitutes 10% of adrenal weight dark red or brownish in colour secretion of catecholamines Stroma: loose connective tissue with: dense plexus of fenestrated capillaries preganglionic sympathetic fibers in medulla

  30. ADRENAL CORTEX histology Zonation: zona glomerulosa: narrow outer zone 15% of cortical volume closely packed ovoid or round clusters of: small columnar or pyramidal cells zona fasciculata: thick middle zone 80% of cortical volume long straight cords (1-2 cell thick) of: large polyhedral cells zona reticularis: thin inner zone 5% of cortical volume anastomosing cords of: smaller cells

  31. ADRENAL GLAND histology Capsule Zona glomerulosa Zona fasciculata Zona reticularis Medulla

  32. ADRENAL CORTEX histology Zona glomerulosa cells: small columnar or pyramidal cells densely stained spherical nucleus pale cytoplasm: abundant sER numerous large mitochondria multiple Golgi complexes free ribosomes sparse lipid droplets secrete mineralocorticoids (aldosterone)

  33. ADRENAL CORTEX histology Zona fasciculata cells: large polyhedral cells (binucleate) lightly stained spherical nucleus pale-staining vacuolated cytoplasm: abundant sER numerous tubular mitochondria well-developed Golgi apparatus rER numerous lipid droplets secrete glucocorticoids (cortisol)

  34. ADRENAL CORTEX histology Zona reticularis cells: smaller cells darkly stained spherical nucleus darker cytoplasm: large lipofuscin granules well-developed sER numerous tubularmitochondria few lipid droplets secrete weak androgens (DHEA)

  35. ADRENAL GLAND histology Capsule Zona glomerulosa Zona fasciculata

  36. ADRENAL GLAND histology Zona fasciculata cell Sinusoid

  37. ADRENAL MEDULLA histology Structure: ovoid clusters and interconnecting cords of: large columnar cells: chromaffin cells ganglion cells

  38. ADRENAL MEDULLA histology Chromaffin cells: innervated by preganglionic sympathetic fibers!!! large columnar (epitheloid) cells lightly stained large nucleus basophilic cytoplasm: rER Golgi apparatus secretory vesicles: dense core vesicles (large): norepinephrine small secretory vesicles: epinephrine Ganglion cells: characteristic neurons (innervated by preganglionic sympathetic fibers)

  39. ADRENAL GLAND histology Zona reticularis Medulla

  40. ADRENAL GLAND histology Ganglion cell Chromaffin cell

  41. ADRENAL GLAND blood supply Components: capsular arteries ↓ ↓ cortical arterioles medullary arterioles ↓ ↓ cortical sinusoids ↓ medullary sinusoids ↓ medullary veins Medulla receives blood from: medullary arterioles cortical sinusoids t. media: longitudinally oriented bundles of smooth muscle cells adrenomedullary veins

  42. ADRENAL CORTEX function Role of mineralocorticoids: control of electrolyte homeostasis and water balance: ↑ sodium reabsorption in kidneys ↑ potassium excretion in kidneys Regulation of mineralocorticoid secretion: by renin-angiotensin system Adrenocortical insufficiency: hyperkalemia, hyponatremia, hypovolemia: hypotension leading to shock Hyperaldosteronism: hypokalemia, hypertension

  43. ADRENAL CORTEX function Role of glucocorticoids: increase glucose availability: ↑ gluconeogenesis ↑ glycogenesis ↑ protein and lipid degradation suppress inflammatory response Regulation of glucocorticoid secretion: by hypthalamo-hypophyseal CRH-ACTH system Hypercortisolism: hyperglycemia, increased protein degradation, hypertension, cental adipose deposition, increased risk of infections

  44. ADRENAL MEDULLA function Role of catecholamines: prepare the body for „fight-or-flight” response: ↑ heart rate ↑ blood pressure ↑ rate of respiration ↑ sweating ↓ digestion Regulation of catecholamine secretion: by sympathetic nervous system conversion of norepinephrine to epinephrine is induced by cortical glucocorticoids Catecholamine overproduction: hypertension

  45. PINEAL GLAND anatomy Pineal gland

  46. PINEAL GLAND histology Pia mater covering Connective tissue septa: lobules Glandular tissue: clumps or cords of: pinealocytes interstitial (glial) cells: similar to astrocytes neurons: processes to habenular nucleus (medial), pretectal nuclei, hypothalamus Fenestrated capillaries Brain sand (corpora arenacea): concentric basophilic concretions: calcification on secreted proteins increase in number with age reference point on radiographic and CT images

  47. PINEAL GLAND histology Pia mater Pineal recess Brain sand Posterior commissure

  48. PINEAL GLAND histology Pinealocytes: predominant cell type cells with cytoplasmic processes deeply infolded large nucleus, 1-2 nucleolus pale cytoplasm: few organelles dense core secretory vesicles in cytoplasmic processes processes are associated with: capillaries – neuroendocrine activity pineal neurons: axo-dendritic synapses secrete melatonin: indolamine

  49. PINEAL GLAND histology Pinealocytes Glial cell

  50. PINEAL GLAND histology Neuron

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