Endocrine glands (cells)Endocrine glands (cells)

Hormone secreting cells or glands.Hormone secreting cells or glands.

May be in a form of scattered cells as May be in a form of scattered cells as enteroendocrine cells of GIT.OR in a form enteroendocrine cells of GIT.OR in a form of gland as pituitary and thyroid glands.of gland as pituitary and thyroid glands.

Endocrine glands have cells that arranged Endocrine glands have cells that arranged in columns or cords separated by in columns or cords separated by fenestrated blood capillaries EXCEPT fenestrated blood capillaries EXCEPT thyroid gland in which cells arethyroid gland in which cells are arranged arranged to form follicles.to form follicles.

•Development of Hypophysis (pituitary gland)

Hypophysis (pituitary gland)

Hypophsis (pituitary gland)It develops from 2 different tissues:It develops from 2 different tissues:1-Ectodermal epithelial tissue: 1-Ectodermal epithelial tissue: of the roof of the of the roof of the

developing mouth---Rathke’s pouch giving developing mouth---Rathke’s pouch giving AdenohypophsisAdenohypophsis (Anterior pituitary). (Anterior pituitary).

2-Ectodermal neural tissue of 2-Ectodermal neural tissue of dienchephalon-dienchephalon-------NeurohypophsisNeurohypophsis (Posterior (Posterior pituitary).pituitary).

Parts of hypophsisParts of hypophsis1-Adenohypophysis1-Adenohypophysis 2- 2-

NeurohypophysisNeurohypophysis a-Pars distalis. a-Pars nervosa.a-Pars distalis. a-Pars nervosa.b-Pars tuberalis. b-Infundibulum.b-Pars tuberalis. b-Infundibulum.c-Pars intermedia. c- Median c-Pars intermedia. c- Median

eminence.eminence.

Blood supply and control of Blood supply and control of secretionsecretion Superior hypophseal arteries supply the pars Superior hypophseal arteries supply the pars

tuberalis and the infundibulum and give tuberalis and the infundibulum and give primary capillary plexus in the median primary capillary plexus in the median eminence.eminence.

Inferior arteries supply the pars nervosa and Inferior arteries supply the pars nervosa and send few branches to the ant. lobesend few branches to the ant. lobe

The hypophseal portal system of veins delivers The hypophseal portal system of veins delivers neurosecretory hormones from the primary neurosecretory hormones from the primary capillary plexus of the median eminence to the capillary plexus of the median eminence to the secondary capillary plexus of the pars distalis.secondary capillary plexus of the pars distalis.

These hypothalamic hormones stimulate or These hypothalamic hormones stimulate or inhibit the secretion of cells of pars distalis.inhibit the secretion of cells of pars distalis.

Pars nervosa (Neurohypophsis)

• Does not contain secretory cells.Does not contain secretory cells.• Does not contain cell bodies of neurons.Does not contain cell bodies of neurons.• Is rich in unmyelinated nerve axons.Is rich in unmyelinated nerve axons.• Is rich in fenestrated Is rich in fenestrated

blood capillaries.blood capillaries.• Contains Herring bodies Contains Herring bodies

that contain vasopressin (ADH)that contain vasopressin (ADH)

& oxytocin H. that are & oxytocin H. that are

secreted by hypothalamus (.secreted by hypothalamus (.• Contains supporting glial cells called pituicytes.Contains supporting glial cells called pituicytes.

Adenohypophysis (anterior Adenohypophysis (anterior pituitary)pituitary)

• Pars intermedia :Pars intermedia : Contains cysts full of Contains cysts full of colloid &lined with cuboidal epith.It may contain colloid &lined with cuboidal epith.It may contain cords of basophils that secrete MSH.cords of basophils that secrete MSH.

• Pars tuberalis :Pars tuberalis : • It surrounds the hypopheseal It surrounds the hypopheseal • (neural)stalk of neurohypophysis (neural)stalk of neurohypophysis

Most of its cells are basophilic Most of its cells are basophilic

gonadotropic cells that arrangedgonadotropic cells that arranged

in cords separated by bloodin cords separated by blood

capillaries and portal systemcapillaries and portal system

• Pars distalis :

1-Chromophobes:1-Chromophobes: Have no affinity to stain. Have no affinity to stain. Are small pale cells.Are small pale cells. Undifferentiated cells.Undifferentiated cells. 2-Chromophils:2-Chromophils: Have an affinity to the stain. Have an affinity to the stain. They are 2 groups:They are 2 groups: I-AcidophilsI-Acidophils include a- Somatotrophs that secrete include a- Somatotrophs that secrete

somatotropin or growth Hsomatotropin or growth H b-Mammotrophs that secrete b-Mammotrophs that secrete

mammotropin or prolactin H.mammotropin or prolactin H. II-BasophilsII-Basophils include a-Thyrotrophs that secrete TSH. include a-Thyrotrophs that secrete TSH. b-Corticotrophs that secrete b-Corticotrophs that secrete

ACTH.ACTH. c-Gonadotrophs that secrete 2 c-Gonadotrophs that secrete 2

types of hormones:types of hormones: -FSH -FSH in females it stimulates in females it stimulates

follicular maturation. In males it stimulate follicular maturation. In males it stimulate spermatogenesis.spermatogenesis.

-LH -LH in females it stimulates in females it stimulates ovulation. In males it stimulate Lyedig cells(interstitial ovulation. In males it stimulate Lyedig cells(interstitial cells) to secrete testosterone.cells) to secrete testosterone.

Anterior pituitary (Adenohypophsis)Anterior pituitary (Adenohypophsis)

Medical applicationMedical application

Pituitary benign tumors.Pituitary benign tumors. Effects of pituitary Hormones on the Effects of pituitary Hormones on the

mammary gland.mammary gland.

Prolactin---stimulate milk formation.Prolactin---stimulate milk formation.

Oxytocin---stimulate milk ejectionOxytocin---stimulate milk ejection

Parathyroid Parathyroid glandsglands

They are 4 glands on the post.of thyroid gland.They are 4 glands on the post.of thyroid gland. Each gland has its capsule and thin septae.Each gland has its capsule and thin septae. The parenchyma is formed of chief cells, The parenchyma is formed of chief cells,

oxyphil cells, blood capillaries and adipose oxyphil cells, blood capillaries and adipose tissue (in adults).tissue (in adults).

Chief cells are slightly eosinophilic, rich in rER Chief cells are slightly eosinophilic, rich in rER and secrete parathyroid hormone ( bl.calcium).and secrete parathyroid hormone ( bl.calcium).

Oxyphil cells are, arranged in groups or Oxyphil cells are, arranged in groups or clusters, deep eosinophilic (rich in clusters, deep eosinophilic (rich in mitochondria and glycogen) and of unknown mitochondria and glycogen) and of unknown function (inactivated chief cells).function (inactivated chief cells).

Thyroid & Thyroid & parathyroid parathyroid glandsglands

Parathyroid glandParathyroid gland

Ant. lobe of Ant. lobe of pituitarypituitary

Post. lobe of Post. lobe of pituitarypituitary

Parathyroid glandParathyroid gland

Thyroid glandThyroid gland Is covered by CT.capsule thatIs covered by CT.capsule that

sends septae to divide it into lobules.sends septae to divide it into lobules. Its parenchyma is formed ofIts parenchyma is formed of

follicles that are separatedfollicles that are separated

by reticular fibers, parafollicularby reticular fibers, parafollicular

cells and fenestrated blood capillaries.cells and fenestrated blood capillaries. The follicles are formed of follicular cells The follicles are formed of follicular cells

(squamous to columnar) & contain colloid.(squamous to columnar) & contain colloid. Follicular cells are basophilic, and rich in RER, Follicular cells are basophilic, and rich in RER,

mitochondria and apically located lysosomes.mitochondria and apically located lysosomes. Parafollicular cells secrete calcitonin (decreases Parafollicular cells secrete calcitonin (decreases

Bl.Calcium level). Bl.Calcium level).

Thyroid follicles and Thyroid follicles and parafollicular cells (clear cells)parafollicular cells (clear cells)

Follicular cellsParafollicularcell

Suprarenal (adrenal) glandsSuprarenal (adrenal) glands It has a thick capsule that sends septae.It has a thick capsule that sends septae. Suprarenal cortex (80% of the gland) produces Suprarenal cortex (80% of the gland) produces

mineralocorticoids, glucocorticoids (cortisol and mineralocorticoids, glucocorticoids (cortisol and corticosterone), and androgens.corticosterone), and androgens.

The cortex is regulated by ACTH of ant. The cortex is regulated by ACTH of ant. Pituitary and angiotensin II.Pituitary and angiotensin II.

Suprarenal medulla produces epinephrine and Suprarenal medulla produces epinephrine and norepinephrine and is regulated by the norepinephrine and is regulated by the sympathetic nervous system.sympathetic nervous system.

The cortex is rich in fenestrated (without The cortex is rich in fenestrated (without diaphragm) sinusoidal capillaries.diaphragm) sinusoidal capillaries.

The medulla receives a dual blood supply: a. The medulla receives a dual blood supply: a. from cortical arteries and b. from cortical from cortical arteries and b. from cortical capillary beds.capillary beds.

Adrenal glandAdrenal gland

It is formed of:

I. CortexI. Cortex that is composed of:

A-Zona glomerulosa.

B-Zona fasiculata.

C-Zona reticularis.

II.MedullaII.Medulla

Adrenal glandAdrenal gland

Adrenal cortex: zona glomerulosa

*Is formed of cords and clusters of small columnar cells that are rich in SER and mitochondria.

*Produces Aldosterone hormone that affect renal distal tubules.

Adrenal cortex: zona fasiculata Adrenal cortex: zona fasiculata (spongiocytes)(spongiocytes)

*It is the intermediate and the largest layer of the cortex.

*It is formed of columns of large polyhedral cells that are separated by longitudinal sinusoidal capillaries.

*It cells are rich in lipids so they appear empty (spongiocytes).

*Its cells are rich in mitochondria (tubular cristae),SER and lipofucin pigment.

*Its cells secrete glucocoticoids.

*It is regulated by ACTH of pituitary.

Adrenal cortex:zona Adrenal cortex:zona reticularis.reticularis.

*It is the innermost layer of adrenal cortex.

*It is formed of anastomosing cords of deep acidophilic cells.

*Its cells contains few lipofucin and lipid droplets.

*The cells secrete androgens.

Medulla of Medulla of adrenal glandadrenal gland

*It the central portion of the adrenal gland.

*It is completely invested with adrenal cortex (not separated from it by CT. septa)

*It is formed of:

1.Chromaffin cells that contains granules of catecholamine as that of sympathetic NS.(They produce epinephrine and norepinephrine). They stain deep brown with chromic salts.

2.2.Sympathetic ganglionSympathetic ganglion cells scattered in CT. Relay on chromaffin cells.

Adrenal gland Thyroid Adrenal gland Thyroid glandgland