Adipose tissue is a specialized connective tissue that serves as a main storage site for triglycerides (fat), and is found in two forms, brown and white, in mammals. The digital image presented below was captured with the MIC-D and reveals fat globules in a thin section of adipose tissue stained with Sudan IV.

White adipose tissue serves three main functions, but its primary one is to serve as a storage location for energy, in the form of long-chain fatty acids and triglycerides. The tissue also serves secondary duties as a mechanical cushion to protect against impact, and as an insulator to keep the host warm. Located directly beneath the skin, subcutaneous adipose tissue is an especially important heat insulator that has a conductance value approximately one-third that of other tissues.

Deriving its color character from rich vascularization and densely packed mitochondria, brown adipose tissue is found in a variety of locations, depending upon the species and age of the animal. This tissue is metabolically less active in non-hibernating animals, although exposure to cold weather can activate the tissue. In adult mammals, the majority of bulk adipose tissue is composed of a loose association of lipid-filled cells termed adipocytes, which are connected together in a framework of collagen fibers.