Endocrine Glands II Adrenal glandsProf Menna Abdel-Dayem

Adrenal Glands

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

Adrenal Cortex

Zona Glomerulosa

Zona fasciculata

Zona Reticularis

Suprarenal (Adrenal) Cortex

1-Zona Glomerulosa 2-Zona Fasciculata 3-Zona Reticularis

The narrowest zone.

just under the capsule -Columnar cells arranged in arched groups (glomeruli)

surrounded by fenestrated capillaries

-The widest zone.

-Polyhedral cells arranged in narrow & straight cords (fascicles)separated by

fenestrated capillaries

-The deepest zone.

-Polyhedral cells arranged in branching & anastomosing cords separated by blood sinusoids.

L.M. -Columnar cells with

basal rounded nuclei & pale cytoplasm

L.M. Polyhedral cells with central rounded pale

vesicular nuclei . Some cells are binucleated with acidophilic vacuolated cytoplasm ,so

called Spongiocytes.

L.M. Polyhedral cells with central rounded nuclei

& acidophilic cytoplasm

Suprarenal (Adrenal) Cortex

1-Zona Glomerulosa 2-Zona Fasciculata 3-Zona Reticularis

E.M.

Rich in mitochondria,

G.A., sER & few fat droplets

E.M.

Rich in mitochondria,

G.A., s-ER, many fat droplets,

cholesterol & vitamin C

E.M.

Rich in mitochondria, G.A., sER &

few fa t drop le ts . Lipofuscin

pigment (androgens) is commonly

seen

Function:

Secrete mineralocorticoids

mainly Aldosterone which regulate H2O &

Electrolyte balance

(under control of

angiotensin II)

Function:

Secrete glucocorticoids (cortisol) that

regu la te l ip id , pro te in& CHO

m e t a b o l i s m . H a v e a n a n t i -

inflammatory & immuno- suppressive

action.

(under control of ACTH)

Function:

Secrete androgen & small amount of

glucocorticoids

(under control of ACTH)

Adrenal Medulla

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.

Adr

enal

Med

ulla

1. Chromaffin cells:

EM:

• Cytoplasm shows mitochondria, well developed Golgi apparatus, rER & 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 & sex hormones

Secretes adrenalin, noradrenalin & enkephalins

Give –ve chromaffin reaction +ve reaction

Supplied with arterial blood Supplied with arterial & venous blood