Knowra Adrenal medulla Adrenal medulla The inner region of each adrenal gland contains chromaffin cells that release catecholamines, chiefly epinephrine and norepinephrine, into the bloodstream.
Chromaffin cell : A neuroendocrine cell that stores and secretes catecholamines, especially in the adrenal medulla. These are the medulla’s secretory cells, activated by sympathetic nerve signals.
Adrenal gland : An endocrine organ above each kidney, composed of an outer cortex and an inner medulla. The medulla is its inner region, distinct from the steroid-producing cortex.
Pheochromocytoma : A catecholamine-producing tumor arising from chromaffin cells, usually in the adrenal medulla. This tumor can cause episodic or sustained excess secretion from medullary tissue.
Adrenal cortex : The outer region of the adrenal gland, producing steroid hormones such as cortisol, aldosterone, and adrenal androgens. It surrounds the medulla but makes steroid hormones rather than catecholamines.
Neural crest : A transient embryonic cell population that generates diverse structures, including peripheral neurons and adrenal medullary chromaffin cells. Medullary chromaffin cells descend from neural crest cells.
Splanchnic nerves : Autonomic nerves that carry preganglionic sympathetic fibers to abdominal organs and the adrenal medulla. Their preganglionic fibers directly stimulate medullary chromaffin cells.
Catecholamine : A class of molecules derived from tyrosine that includes dopamine, norepinephrine, and epinephrine. These are the medulla’s signature secretions.
Paraganglioma : A neuroendocrine tumor arising from paraganglia outside the adrenal medulla or, less often, within it. It shares chromaffin-cell biology but arises outside the adrenal gland in most cases.
Cortisol : A glucocorticoid steroid hormone produced by the adrenal cortex that regulates metabolism and stress responses. It is a slower, steroid-based stress signal rather than a medullary catecholamine.
Adrenal cortex development : The embryonic formation of the adrenal cortex from mesoderm-derived cells associated with the developing gonad. The cortex has a mesodermal origin, unlike the medulla’s neural crest lineage.
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