- Slides: 31
Endocrine Glands II Adrenal glands Prof Menna Abdel-Dayem
Suprarenal (Adrenal) Glands ● Two endocrine glands in contact with upper border of both kidneys. ● Derived from 2 embryonic sources: the mesoderm gives rise to adrenal cortex & neuroectoderm gives rise to adrenal medulla.
Suprarenal (Adrenal) Glands
Suprarenal (Adrenal) Glands Stroma: Capsule, trabeculae and reticular framework Parenchyma: Cortex Medulla
Suprarenal (Adrenal) Glands Stroma: Capsule: thick, covered with adipose C. T. Trabeculae: thin, descend from the capsule to divide the cortex into compartments. Reticular framework
Suprarenal (Adrenal) Cortex 1 -Zona Glomerulosa 2 -Zona Fasciculata 3 -Zona Reticularis The narrowest zone. -The widest zone. just under the capsule -Polyhedral cells arranged in narrow & -Polyhedral cells arranged in branching & -Columnar cells straight cords arranged in arched groups (glomeruli) (fascicles)separated by surrounded by fenestrated capillaries -The deepest zone. anastomosing cords separated by blood sinusoids. L. M. -Columnar cells with Polyhedral cells with central rounded pale Polyhedral cells with central rounded nuclei basal rounded nuclei vesicular nuclei. & pale cytoplasm Some cells are binucleated with acidophilic vacuolated cytoplasm , so called Spongiocytes. L. M. & acidophilic cytoplasm
Suprarenal (Adrenal) Cortex 1 -Zona Glomerulosa 2 -Zona Fasciculata 3 -Zona Reticularis E. M. Rich in mitochondria, G. A. , s. ER & few fat droplets G. A. , s-ER, many fat droplets, few fat droplets. Lipofuscin pigment cholesterol & vitamin C (androgens) is commonly seen Function: Secrete mineralocorticoids Secrete glucocorticoids (cortisol) that Secrete androgen & small amount of mainly Aldosterone which regulate H 2 O & regulate Electrolyte balance metabolism. (under control of inflammatory & immuno- suppressive angiotensin II) action. lipid, protein& Have an CHO anti- glucocorticoids
Adrenal Medulla 1. Chromaffin cells: – Modified sympathetic neurons that have lost their processes and became secretory cells. – Polyhedral cells arranged in branching cords separated by blood sinusoids. – Have basophilic cytoplasm rich in fine granules that stain brown with chromium salts & central rounded pale nuclei.
Adrenal Medulla 1. Chromaffin cells: EM: • Cytoplasm shows mitochondria, well developed Golgi apparatus, r. ER & membrane-bound secretory granules. • There are 2 types of cells at ultrastructural level: a) Adrenalin secreting cells: with less dense & homogeneous granules, i. e. the contents fill the granules. b) Noradrenalin secreting cells: with more dense granules and peripheral clear halo beneath the membrane. The secretory granules also contain opiate-like peptides = enkephalins.
Adrenal Medulla 2. Sympathetic nerve cells: Stellate nerve cells scattered between chromaffin cells to stimulate their secretory activity. Innervated by preganglionic sympathetic nerve fibers.
Functions of the Adrenal Medulla • Secrete adrenalin (epinephrine) & noradrenalin (norepinephrine) in response to stress (fight, flight & fright). • During normal activity, the medulla continuously secretes small amounts of the 2 hormones.
Migrated sympathetic ganglion: 1 - Innervation ………. 2 - Embryologic origin ………… 3 - contain …………
Paraganglia Masses of chromaffin cells scattered in close association with the sympathetic ganglia. They develop from neuroectoderm (like sympathetic ganglia). Give +ve chromaffin reaction. Function: secrete adrenalin & noradrenalin and enkephalins
Blood Supply Three suprarenal arteries (superior, middle & inferior) pierce the capsule → 3 groups of arterioles (capsular, cortical & medullary). The cortical capillaries drain into veins of medulla which join to form suprarenal vein that leave the gland
Cortex and Medulla Cortex Medulla Mesodermal in origin Ectodermal Formed of 3 zones (glomerulosa, fasciculate & reticularis) Two types of cells (chromaffin& nerve cells) Essential to life (corticosteroids) Less essential Secretes mineralocorticoids, glucocorticoids & Secretes adrenalin, noradrenalin & enkephalins sex hormones Give –ve chromaffin reaction +ve reaction Supplied with arterial blood Supplied with arterial & venous blood