Superior adrenal artery – arises from the inferior phrenic artery.The adrenal glands have a rich blood supply via three main arteries: Chromaffin cells also secrete enkephalins which function in pain control. These hormones produce a ‘ flight-or-fight‘ response. It contains chromaffin cells, which secrete catecholamines (such as adrenaline) into the bloodstream in response to stress.

The medulla lies in the centre of the gland, and is dark brown in colour. Fig 3 - Histological appearance of the cortex and medulla of the adrenal gland. Fig 2 - Posterior view of the abdomen, demonstrating the anatomical relations of the adrenal glands. It also secretes a small amount of corticosteroids. Zona reticularis – produces and secretes androgens such as dehydroepiandrosterone (DHES).It also secretes a small amount of androgens. Zona fasciculata – produces and secretes corticosteroids such as cortisol.Zona glomerulosa – produces and secretes mineralocorticoids such as aldosterone.Functionally, the cortex can be divided into three regions (superficial to deep): It secretes two cholesterol derived hormones – corticosteroids and androgens. The cortex and medulla synthesise different hormones. Medulla – derived from the ectodermal neural crest cells.Cortex – derived from the embryonic mesoderm.They are two separate endocrine glands, with different embryological origins: The outer cortex and inner medulla are the functional portions of the gland. The adrenal glands consist of an outer connective tissue capsule, a cortex and a medulla. Veins and lymphatics leave each gland via the hilum, but arteries and nerves enter the glands at numerous sites.

Hormones produced by the adrenal glands