Soft tissue
Histology-brown adipose

Topic Completed: 1 August 2012

Minor changes: 16 December 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Brown fat [title]

Vijay Shankar, M.D.
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Cite this page: Shankar V. Histology-brown adipose. website. Accessed May 7th, 2021.
  • Also called Brown Adipose Tissue (BAT)
  • More conspicuous in infants (5% of body weight) and children; replaced with white fat over time
  • Persists in adults in interscapular region, neck, mediastinum, axilla, retroperitoneum (perirenal)
  • Substantial amounts of metabolically active brown fat are present in healthy adults (N Engl J Med 2009;360:1518)
  • Main function is heat production (nonshivering thermogenesis), mediated through a dense vascular system and sympathetic nerves (Physiol Rev 2004;84:277)
  • Brown fat mitochondria express uncoupling protein (UCP1), which uncouples fatty oxidation from ATP generation, which causes energy to be dissipated as heat
  • Cold exposure leads to sympathetic stimulation of brown fat via norepinephrine binding to beta adrenergic receptors, then oxidation of fatty acids and heat production
  • Protein-tyrosine phosphatase 1B is a modulator of brown fat adipogenesis (PLoS One 2011;6:e16446)
  • Moderate intermittent stress can stimulate brown adipose tissue growth and thermogenic activity
Diagrams / tables

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Sites of brown fat

Clinical features
  • Increased presence is associated with alcohol abuse, malnourishment and cachexia (may maintain body temperature in those with diminished subcutaneous fat), cardiovascular disease (Arch Pathol Lab Med 1992;116:1152); also Duchenne‚Äôs muscular dystrophy (Arch Pathol Lab Med 1988;112:550)
  • Brown fat thermogenesis is visible with a thermal (infrared) camera in infants over neck and interscapular area
  • Also important in animals coming out of hibernation, allowing them to rewarm quickly
Gross description
  • Red-brown (less lipid) to tan (more lipid) due to vascularity and numerous mitochondria
  • Has glandular and lobular appearance
Microscopic (histologic) description
  • Lobules of adipocytes, capillaries, nerves and connective tissue
  • Adipocytes are smaller (25 - 40 microns) than in white fat, are polygonal with acidophilic multivacuolated and granular cytoplasm and central spherical nucleus with fine indentations
Microscopic (histologic) images

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Multivacuolated cytoplasm

Positive stains
Electron microscopy description
  • Numerous mitochondria and smaller amounts of lipid droplets
Additional references
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