Adrenal gland

A pair of adrenal glands (also called suprarenal glands, reflecting their position at the anterior/upper end of each kidney) each have two anatomically and functionally distinct regions: an outer cortex and an inner medulla.

The adrenal cortex itself has three histologically distinct zones. Zona glomerulosa, the thin outermost layer (about 15% of the cortex), secretes mineralocorticoids, which regulate salt and water balance. Zona fasciculata, the wide middle layer (about 75% of the cortex, by far the largest zone), secretes glucocorticoids such as cortisol and corticosterone, along with trace amounts of adrenal androgen and oestrogen. Zona reticularis, the innermost zone (about 10% of the cortex), secretes adrenal androgens, trace oestrogen, and some glucocorticoids as well. …