Ninety percent of medullary cells are the epinephrine-secreting type, and 10% are the norepinephrine-secreting type.

Separate dopamine-secreting cells have not been identified. Morphologically, two types of medullary cells can be distinguished: epinephrine-secreting cells, which have larger, less dense granules, and norepinephrine-secreting cells, which have smaller, very dense granules. The granules contain the catecholamines epinephrine and norepinephrine. Histologically, these cells and granules have a high affinity for chromium salts ( chromaffin reaction) and thus are called chromaffin cells and contain chromaffin granules. Medullary parenchymal cells accumulate and store their hormone products in prominent, dense secretory granules, 150–350 nm in diameter. This relationship is analogous to the other sympathetic ganglia, which connect preganglionic cholinergic sympathetic nerve fibers with postganglionic fibers using catecholamines (mainly norepinephrine) as neurotransmitters. The adrenal medulla can be regarded as a specialized sympathetic ganglion, in which preganglionic sympathetic nerve fibers (using acetylcholine as a neurotransmitter) directly make contact with postganglionic cells, which secrete catecholamines (mainly epinephrine) directly into the circulation. Medullary cells are innervated by cholinergic preganglionic nerve fibers that reach the gland via the splanchnic nerves. Adrenal gland disorders occur when the adrenal glands produce too much or too little of these hormones. Adrenal Insufficiency Adrenal insufficiencyis a rare disorder. These abnormalities of the adrenal function can be caused by various diseases of the adrenal glands or the pituitary gland.

Embryologically, the adrenal medullary cells derive from neural crest cells. The adrenal glands, located on the top of each kidney, are responsible for releasing different hormones. The two common ways in which adrenal glands cause health issues are by producing too little or too much of certain hormones, which leads to hormonal imbalances. The adrenal medulla is made up of polyhedral cells arranged in cords or clumps.

Adrenal gland issues