Adrenal glands

Adrenal glands' are a pair of endocrine glands. They are located at the upper pole of the kidneys and in its fatty capsule. Their mass is about 8 g. On the surface there is a capsule of dense collagenous connective tissue from which the septum extends. Attached to this connective tissue are reticular fibres providing support to the parenchyma cells. The adrenal glands are composed of cortex and medulla. The cortex and the medulla are different in structure, function and origin.
 * Cortex, originating from the mesodermal coelomic epithelium, produces steroids;
 * Medulla, originating from neuroectoderm neural crest, produces catecholamines.

The blood supply comes by way of three arteries: superior, middle and inferior suprarenal artery. They further branch to form the subcapsular plexus, from which the arteries of the capsule and the arteries of the cortex, which anastomose throughout the cortex, are further formed and enter the veins of the marrow. This arrangement is of functional importance because glucocorticoids flowing from the cortex into the marrow act enzymatically to convert norepinephrine into adrenaline. Regulation of adrenal cortical hormone secretion is provided by adrenocorticotropic hormone (ACTH) from the adenohypophysis.