Adrenal gland & paraganglia


Histology-adrenal medulla

Topic Completed: 1 April 2013

Minor changes: 1 October 2021

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PubMed Search: Adrenal medulla histology physiology [TIAB]

Severino Rey Nodar, M.D., Ph.D.
Pallav Gupta, M.D.
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Cite this page: Nodar SR, Gupta P. Histology-adrenal medulla. website. Accessed December 8th, 2021.
Definition / general
  • Synthesizes and secretes primarily catecholamines (norepinephrine and epinephrine) in response to signals from preganglionic nerve fibers in sympathetic nervous system
Essential features
  • Region with basophilic staining cells with granular cytoplasm and no stored lipid
  • Composed of neural crest cells called chromaffin cells (also called pheochromocytes, medullary cells) with a multilineage differentiation potential
  • Produces catecholamines (norepinephrine and epinephrine)
  • Chromaffin cells: take up chromium salts strongly, turn brown-black after exposure to Zenker solution (potassium dichromate), produce catecholamines
  • Norepinephrine: local transmitter, chiefly of sympathetic postganglionic neurons
  • Epinephrine: systemic transmitter, interacts with alpha and beta adrenergic receptors
  • See also Anatomy
  • Innervated by axons from lower thoracic and lumbar preganglionic neurons via splanchnic nerves
  • Dopamine, which is precursor of norepinephrine, is found in adrenal medulla and peripheral sympathetic nerves and acts as a neurotransmitter in CNS
  • Catecholamines affect cardiovascular and metabolic processes, causing increase in heart rate, blood pressure, myocardial contractility and cardiac conduction velocity (Melmed S, Polonsky KS, Larsen PR, Kronenberg HM: Williams Textbook of Endocrinology, 12th Edition, 2011)
Diagrams / tables

Images hosted on other servers:

Synthesis of catecholamines

Microscopic (histologic) description
  • Chromaffin cells:
    • Arranged in small nests and cords separated by prominent vasculature
    • Large polygonal cells with poorly outlined borders
    • Abundant granular and usually basophilic cytoplasm
    • Mild variation in cell size
    • Occasionally has PAS+ hyaline droplets
  • Sustentacular cells:
    • Supporting spindle cells at periphery of nests of chromaffin cells
    • Associated with rich vasculature
    • Difficult to identify with routine staining
  • Ganglion cells:
    • Occasional single cells or small clusters associated with myelinated nerve bundles
  • Vasculature:
    • Central vein has thick wall of smooth muscle
    • Also many venous channels which drain blood from cortical sinusoids, pass through medulla to drain into medullary vein
Microscopic (histologic) images

Contributed by Debra Zynger, M.D.

Basophilic cells

Nested architecture

Positive stains
Electron microscopy description
  • Numerous mitochondria
  • Norepinephrine producing cells have 250 nm electron opaque neurosecretory granules, with prominent halo between granule membrane and dense core
  • Epinephrine producing cells have 190 nm finely granular neurosecretory granules, filling the enclosing membrane and no halo
  • Moderate amount of rough endoplasmic reticulum, interdigitating blunt cytoplasmic processes with poorly developed cell junctions
  • Sustentacular cells have moderate amounts of rough endoplasmic reticulum and occasional lipid droplets but no neurosecretory granules
Board review style question #1
    Which of the following is expressed in the adrenal medulla? 

  1. Chromogranin and GATA3
  2. CK7 and CK20
  3. Inhibin and calretinin
  4. MelanA and SF1
Board review style answer #1
A. Chromogranin and GATA3. Inhibin, calretinin, MelanA and SF1 are expressed in the adrenal cortex but not the adrenal medulla. CK7 and CK20 are not expressed in the adrenal medulla or adrenal cortex.

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Reference: Adrenal medulla
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