ADRENAL OR SUPRARENAL GLAND ::
There are two adrenal glands situated on the top of each kidney It is therefore also named as suprarenal gland They fit like a cap on each kidney
Structurally as well as functionally adrenal gland is divided into two parts the cortex and medulla Whole gland is covered by connective tissue capsule which sends trabeculae inside
Cortex consists of three layers:Zona -glomerulosa Zona-fasciculata (radiata) and Zona -reticulata
Zona glomerulosa consists of 2-3 layers of columnar cells arranged parallel to the surface in the alveoli form This layer secretes mineralocorticosteroids -aldosterone
Zona fasciculata or radiata comprises of polyhedral cells arranged in perpendicular rows This layer secretes glucocorticosteroids -cortisone corticosterone 11-dehydro-or 17-hydrocorticosteroids This layer occupies the largest part
Zona reticulata is an irregular network of rows of cells The meshwork of cells is filled with sinusoids lined by reticuloendothelial cells This layer secretes various sex hormones :progesterone estrogen and androgens
Adrenal medulla lies in central part of the gland The cells are larger and more deeply staining than the cortex cells are arranged in groups or clusters and between them are large and small blood sinusoids The secretion of adrenal - medulla is adrenaline
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