Gland
Adrenal medulla
Chromaffin cells linking sympathetic nerves to blood
High-yield
Preganglionic cholinergic fibers contact chromaffin cells without a separate postganglionic neuron. Related chromaffin tissue also occurs outside the adrenal gland.
Overview
Medullary chromaffin cells are neural-crest-derived endocrine cells closely related to sympathetic neurons. Preganglionic fibers activate them directly, releasing catecholamines into the circulation. Their vascular environment links medullary function to cortical steroid production.
Reference facts
- Location
- Forms the inner adrenal region, with some intermingling of cortical and chromaffin cells at the interface.
- Hormones
- Releases predominantly epinephrine and norepinephrine; their proportions vary with physiological state and cell composition.
- Blood supply
- Receives direct medullary arterioles and cortical sinusoidal blood. High local glucocorticoid exposure supports PNMT expression and epinephrine synthesis.
- Innervation
- Preganglionic sympathetic fibers reach chromaffin cells through thoracic splanchnic and celiac-region pathways and release acetylcholine.
- Function
- Provides circulating catecholamines that rapidly influence cardiovascular activity, fuel availability and stress responses.
Clinical correlation
Pheochromocytomas arise from adrenal chromaffin tissue and may produce episodic or sustained catecholamine effects such as hypertension, palpitations, sweating and headache. Some are associated with inherited susceptibility; the symptom pattern is not uniform.
Frequently asked questions
Where is the adrenal medulla located?
Forms the inner adrenal region, with some intermingling of cortical and chromaffin cells at the interface.
What does the adrenal medulla secrete?
Releases predominantly epinephrine and norepinephrine; their proportions vary with physiological state and cell composition.
What does the adrenal medulla do?
Provides circulating catecholamines that rapidly influence cardiovascular activity, fuel availability and stress responses.
What is the blood supply of the adrenal medulla?
Receives direct medullary arterioles and cortical sinusoidal blood. High local glucocorticoid exposure supports PNMT expression and epinephrine synthesis.