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Adrenal cortex Histological structure, Hormones of Adrenal Cortex -…
Adrenal cortex
Histological structure
The adrenal gland is covered by a connective tissue capsule from which
septa extend into the gland substance.
The mature human adrenal
cortex consists of three distinct layers or zones of cells.
adrenal cortex
Zona glomerulosa,
constituting outer 1/5 of the cortex,
is a small zone present under the capsule.
It consists of cells that are arranged as inverted U-shaped formations, or acinus-like groups.
It is the site of aldosterone and corticosterone synthesis.
Aldosterone is the principal
mineral corticoid of the human adrenal cortex.
Zona fasciculata
is the widest zone
forming middle 3/5 of the
cortex.
It is made up of cells that are arranged in two cells thick
straight columns.
Sinusoids intervene between the columns
and cells appear clear or vacuolated in stained sections because of high lipid(cholesterol) content.
Zona reticularis
forms the inner 1/5 of the cortex.
It is made up of a network of compactly arranged cords of cells that branch and anastomose with each other to form a kind of network
(hence the name zona reticularis).
These cells contain fewer lipids.
Adrenal medulla
essentially represents an enlarged and specialized sympathetic ganglion.
Histologically, it is made up of chromaffin cells,
innervated by preganglionic sympathetic neurons.
Chromaffin cells.
The cells forming adrenal medulla show yellow granules in their
cytoplasm (i.e. chromaffin reaction) and hence called chromaffin cells.
These cells are columnar or polyhedral
and are arranged in all groups
or columns that are separated by wide sinusoids.
Hormones of Adrenal Cortex
Hormones secreted by adrenal cortex, called corticosteroids, can be
grouped as:
Glucocorticoids,
which include
cortisol and
corticosterone,
which have a widespread effect on glucose and protein metabolism.
Mineral corticoids.
Aldosterone is the chief mineralocorticoid.
It regulates the sodium balance and
ECF volume in the body.
Adrenal sex steroids.
These include
androgenic substances such as
dehydroepiandrosterone (DHEA)
and its sulphate ester.
In addition,
adrenal cortex also secretes
biosynthetic precursors of
3 end products
progesterone,
11-deoxycorticosterone and
11-deoxycortisol.