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Chromaffin cell: Wikis

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Adrenal gland. (Medulla labeled at bottom right.)

Chromaffin cells are neuroendocrine cells found in the medulla of the adrenal gland (suprarenal gland - located above the kidneys) and in other ganglia of the sympathetic nervous system. They are derived from the embryonic neural crest.

In the fifth week of (human) fetal development, neuroblast cells migrate from the neural crest to form the sympathetic chain and preaortic ganglia. The cells migrate a second time to the adrenal medulla. Chromaffin cells also settle near the sympathetic ganglia, vagus nerve, paraganglia, and carotid arteries. In lower concentrations, extra-adrenal chromaffin cells also reside in the bladder wall, prostate, and behind the liver.

Contents

Function

Chromaffin cells of the adrenal medulla are innervated by the splanchnic nerve and secrete adrenaline (epinephrine), noradrenaline (norepinephrine), and enkephalin endogenous ligands, or specifically endorphins as they are internally derived and bind to the body's opioid receptors, into the blood stream. As such, they play an important role in the fight-or-flight response. They are also referred to as granules and this is where the enzyme dopamine-hydroxylase catalyzes the conversion of dopamine to noradrenaline. Distinct N and E cell forms exist (also Na and A cells in British nomenclature - noradrenaline and adrenaline); the former produce norepinephrine, the latter arise out of N cells through interaction with glucocorticoids, and convert norepinephrine into epinephrine.[1]

Nomenclature

These cells are so-named because they can be visualized by staining with chromium salts. Chromaffin salts oxidize and polymerize catecholamines to form a brown color, most strongly in the cells secreting noradrenaline.

(The enterochromaffin cells are so named because of their histological similarity to chromaffin cells (they also stain yellow when treated with chromium salts), but their function is quite different.)

References

  1. ^ Wheater's Functional Histology, 5th ed. Young, Lowe, Stevens and Heath.

External links

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