Table 1.

Main differences amongst the three types of adipocyte tissue.

Characteristic property	White	Brown	Beige	References
Morphology
(i) Shape	Spherical	Ellipsoid/polygonal	Spherical	[8, 9, 23]
(ii) Cell size	Variable, large (25–200 µm)	Small (15–60 µm)	Variable, smaller than white
(iii) Lipid droplet (LD)	Single large LD	Multiple small LD	Multiple LD with variable size
(iv) Mitochondria	+	+++	++ (upon stimulation)
Development	From Myf5− or Myf5+ precursors	From Myf5+ precursors	From Myf5− or Myf5+ precursors	[23–26]
Location	Subcutaneous and visceral	Suprarenal, paravertebral, supraclavicular	Inguinal, neck (near carotid sheath and musculus longus colli), other locations?	[8, 27]
Function	Energy storage	Heat production	Adaptive thermogenesis	[9]
Uncoupling protein	Nearly undetectable	+++	++ (upon stimulation)	[28, 29]
Adipocyte-type-specific markers	PPARγ, PLIN1, HOXC9, TCF21, TLE3, C/EBPα, Rb, Rip140	LHX8, ZIC1, EPSTI1, PRDM16, CIDEA, ELOVL3	HOXC8, HOXC9, CITED1, CD137, TMEM26, TBX1, CD40	[13, 23, 30, 31]
Vascularization	Low	High	High upon stimulation	[32, 33]
Impact on obesity	Positive	Negative	Negative	[34]
Correlation with insulin resistance	Yes	Probably yes	Probably yes	[35–38]

CD40: CD40 molecule, TNF receptor superfamily member 5; CD137: tumour necrosis factor receptor superfamily, member 9; C/EBPα: CCAAT/enhancer binding protein (C/EBP), alpha; CIDEA: cell death-inducing DFFA-like effector; CITED1: Cbp/p300-interacting transactivator, with Glu/Asp-rich carboxy-terminal domain 1; ELOVL3: ELOVL fatty acid elongase 3; EPSTI1: epithelial stromal interaction 1; HOXC8: homeobox C8; HOXC9: homeobox C9; LHX8: LIM homeobox protein 8; PLIN1: perilipin-1; PPARγ: peroxisome proliferator-activated receptor gamma; PRDM16: PR domain containing 16; Rb (Rb1): retinoblastoma 1; Rip140: nuclear receptor interacting protein 1; TBX1: T-Box 1; TCF21: transcription factor 21; TLE3: transducin-like enhancer of split 3; TMEM26: transmembrane protein 26; ZIC1: zinc finger protein of the cerebellum 1.