Bone and adipose tissue. Coloured scanning electron micrograph (SEM) of bone tissue (top) and the adipocytes (fat cells) that make up adipose connective tissue (bottom). The lipid (fat) deposits, the cells' major component, have been removed. Fat cells are amongst the largest in the body and form a thick insulating layer under the skin. Above is cortical, or compact, bone. It contains blood and lymph vessels and nerves, which enter the bone through lacuna (holes). Cortical bone is made up of concentric layers of a collagen-containing matrix. Magnification: x83 when printed 10 centimetres wide.