Adrenal cortex zones and medulla !
- Organ
The adrenal gland has a three-layer cortex that makes steroids and a medulla that releases adrenaline.
Updated 2026-11-01
See it in 3D: Left adrenal gland · Right adrenal gland
What it is
Each adrenal has a cortex, of mesodermal origin, and a medulla, derived from the neural crest. The cortex has three zones that make, from outside in, mineralocorticoids, glucocorticoids and androgens. The medulla has chromaffin cells that release epinephrine and norepinephrine on sympathetic stimulation. Matching zone, hormone and disease is one of the most asked questions in endocrinology.
Structure
- A connective tissue capsule and, beneath it, the zona glomerulosa with cells in rounded clusters or arcs.
- Zona fasciculata: straight cords of large cells with foamy cytoplasm (lipid washed out in processing).
- Zona reticularis: anastomosing cords of smaller, eosinophilic cells, sometimes with lipofuscin.
- Medulla: large basophilic cells clustered around vessels, with a few ganglion cells.
Function
- Aldosterone retains sodium and excretes potassium in the collecting duct.
- Cortisol raises glucose, damps inflammation and is central to the stress response.
- Epinephrine and norepinephrine drive fight or flight; cortisol arriving through the portal blood helps make epinephrine.
Adrenal zones: hormone, main regulator and disease
| Zone | Hormone | Main regulator | Disease |
|---|---|---|---|
| Glomerulosa | Aldosterone | Angiotensin II and potassium | Primary hyperaldosteronism (Conn syndrome): hypertension and hypokalemia |
| Fasciculata | Cortisol | ACTH | Cushing syndrome from an adenoma or excess ACTH |
| Reticularis | Adrenal androgens (DHEA) | ACTH | Congenital adrenal hyperplasia: virilisation |
| Medulla | Epinephrine and norepinephrine | Preganglionic sympathetic nerves | Pheochromocytoma: spells of hypertension, headache, sweating and palpitations |
| Whole cortex | All three cortical hormones | Hypothalamic-pituitary axis and renin | Primary adrenal insufficiency (Addison disease) |
Markers
- Chromogranin A
- Synaptophysin (medulla)
- Chromaffin reaction
- Metanephrines (lab)
Clinical notes
- Addison disease: destruction of the cortex, mostly autoimmune, though tuberculosis is still a cause in the region; high ACTH darkens the skin.
- Pituitary Cushing: high ACTH thickens the fasciculata and reticularis on both sides; a cortisol-secreting adenoma makes the rest of the cortex atrophy.
- Neuroblastoma: a tumour of the adrenal medulla in young children, derived from the neural crest.
Test yourself
Think of the answer, then tap the question to see it.
Which zone of the adrenal cortex is the thickest and what does it make?
The zona fasciculata, which makes cortisol under ACTH control.
What mainly regulates aldosterone secretion?
Angiotensin II and plasma potassium; ACTH plays a minor part.
From which embryonic tissue does the adrenal medulla derive?
From the neural crest; its chromaffin cells are modified postganglionic sympathetic neurons.
Which adrenal medulla tumour causes spells of hypertension with headache, sweating and palpitations?
Pheochromocytoma, which releases excess catecholamines.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Pituitary: adenohypophysis and neurohypophysis
- Glomerulus and the filtration barrier: podocytes, mesangium, JGA
- Pineal gland and the diffuse endocrine system
Related conditions
Educational content on normal microscopic structure and its clinical relevance; no substitute for studying slides or for a health professional's advice.
Sources: 17.6 The Adrenal Glands (OpenStax, Rice University, 2022); Adrenal Gland (National Cancer Institute, SEER Training Modules, 2026).
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Representative model, for educational purposes only.