Fat cell. Coloured scanning electron micrograph (SEM) of an oval adipocyte (fat cell), forming part of adipose connective tissue. The reticular fibres which cover the cell's surface hold the adipose tissue together. Fat cells mostly consist of lipid deposits and are one of the largest types of human cells. Adipose connective tissue forms a thick insulating layer under the skin, which also acts as a reserve energy store. Magnification: x1,500 at 6x7cm size. x5000 at 7.5x9.5 inch size.