Fat cells. Coloured scanning electron micrograph (SEM) of a section through adipose (fat) tissue showing the adipocytes (fat cells, round). Adipocytes store energy as an insulating layer of fat and the majority of the cell's volume is taken up by a large lipid (fat or oil) droplet. Fat accumulation starts with a few small lipid droplets which coalesce to make one large droplet. When mature, the adipocyte may be 10 or 20 times its original size. Magnification: x750 when printed at 10 centimetres wide.