بسم الله الرحمن الرحيم

1. بسم الله الرحمن الرحيم

2. PITUITARY GLAND ANDTHYROID GLAND

3. HYPOPHYSIS CEREBRI( PITUITARY GLAND )

6. PITUITARY GLAND

8. COMPONENTS • ADENOHYPOPHYSIS CEREBRI: 1- Pars Distalis (pars anterior) 2- Pars Tuberalis 3- Pars Intermedia (B)NEUROHYPOPHYSIS CEREBRI: 1- Median eminence 2- Infundibulum: Neural (Infundibular) Stalk 3- Pars Nervosa

9. DEVELOPMENT

10. DEVELOPMENT • ADENOHYPOPHYSIS: Arises as outpocketing (evagination) of ectoderm from the roof of the primitive mouth of embryo → Rathke’s Pouch → Separates from oral cavity. (B) NEUROHYPOPHYSIS: Arise as a down growth from the floor of diencephalon, without detaching from the brain.

11. PITUITARY GLAND

12. PITUITARY GLAND

13. NEUROHYPOPHYSIS xxxx xxxxxxxx XXXXX

15. PARS NERVOSA

16. PARS NERVOSA

17. PARS NERVOSA

18. PARS NERVOSA

19. PARS NERVOSA

20. NEUROHYPOPHYSIS (A) PARS NERVOSA CONTENTS: 1- Unmyelinated axons ofsecretory neurons situated in supraoptic & paraventricular nuclei (i.e. Axons of hypothalamhypophyseal tract). 2- Herring’s Bodies: contain neurosecretory granules. 3- Fenestrated blood capillaries. 4- Pituicytes: branched glial-like cells. N.B. No secretory cells in pars nervosa.

21. HERRING BODIES - Are blue-black stained distentions of the axons in p. nervosa. - Representing accumulation of neurosecretory granules at axon termini and along the length of the axons in p. nervosa.

22. PITUICYTES Are glial-like cells in p. nervosa. Structure: Have numerous cytoplasmic processes with gap junctions. Functions: 1- Support the axons of the p. nervosa. 2- May have a trophic function.

23. Function of p. nervosa: Storage & release of: 1- Vasopressin (ADH) 2- Oxytocin

24. P. DISTALIS, P. INTERMEDIA &P. NERVOSA

31. PARS DISTALISBlue arrow: acidophilsRed arrow: basophilsYellow arrow: chromophobes

32. Blue arrow: acidophilsRed arrow: basophilsYellow arrow: chromophobes

33. PARS DISTALIS

34. PARS DISTALIS

35. GH CELLS

36. PROLACTIN CELLS

37. ACTH CELLS

39. PARS DISTALIS Stroma: 1- Fibrous capsule. 2- Scant C.T. located mainly around aa &vv. (hypophyseal arteries & portal veins). 3- Reticular fibers: around the cords of cells & “ the sinusoidal capillaries.

40. PARS DISTALIS Parenchyma: 1- Cords of parenchymal cells. 2- Sinusoidal capillaries: With fenestrated endothelium.

41. PARS DISTALISTypes of parenchymal cells • Chromophils: a- Acidophils: 1- Somatotrophs (Somatotropic cells). 2- Mammotrophs (Mammotropic cells). b- Basophils: 1- Thyrotrophs (Thyrotropic cells)(TSH) 2- Gonadotrophs (Gonadotropic cells) (FSH, LH) 3- Corticotrophs (ACTH, Lipotropic H) 4- Melanotropes ?????????????

42. Types of parenchymal cells (2) Chromophobes: may represent: 1- stem cells. 2- degranulated chromophils. 3- degenerated cells. (3) Folliculostellate cells: Structure: have long processes with gap j. Function: Not clear ( are non-secretory) ???(may be:1-supporting, 2-phagocytic).

43. PARS TUBERALIS Structure: Cuboidal basophilic cells. Function: Possibly contain FSH & LH.

44. PARS INTERMEDIA(ZONA INTERMEDIA) L/M: 1-Numerous colloid-containing cysts (Rathke’s cysts): Are lined with cuboidal cells. Are remnants of Rathke’s pouch. 2-Cords of weakly basophilic cells. 3- Network of blood capillaries. Function: Secrete proopiomelanocortin→ Gives: α-MSH, Corticotropin, ß-lipotropin & ß-endorphin. N.B.α-MSH in human stimulates prolactin release.

45. BLOOD SUPPLY

46. ------ X x x

47. BLOOD SUPPLY (1)Sup. Hypoph. Arteries (Rt & Lt): To median eminence & Neural stalk → 1ry capillary plexus of fenestrated capillaries → Hypophyseal portal Veins (or venules) → 2ry capillary plexus of capillaries in adenohyp [Hypophyseal Portal System ] [ “ “ Circulation ] It carries neurohormones from median eminence to adenohypophysis. (2) Inf. Hypoph. Arteries (Rt & Lt): Mainly to pars nervosa, They are Not participating in hypophyseal portal circulation. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

48. THYROID GLAND

49. THYROID GLAND