Adrenal gland and paraganglia
Histology - Adrenal medulla

Author: Severino Rey Nodar, M.D., Ph.D. (see Authors page)

Revised: 8 August 2017, last major update April 2013

Copyright: (c) 2002-2017,, Inc.

Related: Histology-Adrenal cortex
Cite this page: Histology, Adrenal medulla. website. Accessed January 21st, 2018.
Definition / general
  • 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; also sustentacular cells
  • Chromaffin cells: arranged in small nests and cords separated by prominent vasculature; take up chromium salts strongly, turns brown-black after exposure to Zenker's solution (potassium dichromate); 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 cells, spindle cells at periphery of nests of chromaffin cells; associated with rich vasculature; S100+, difficult to identify with routine staining
  • Ganglion cells: occasional single cells or small clusters associated with myelinated nerve bundles
  • 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

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Adrenal medulla

Positive stains
  • Chromogranin, synaptophysin, neurofilament, tyrosine hydroxylase, epinephrine and S100 (sustentacular cells)
Negative stains
  • Keratin, vimentin
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