Caption

Capillary cross-section, coloured transmission electron micrograph (TEM). The lumen (white) is surrounded by the capillary lining, made up of endothelial cells. The individual cells are arranged longitudinally to the axis of the capillary. The nucleus of one such endothelial cell appears as a semicircle (green) at the top of the image. To the lower right of the lumen is part of a pericyte (the nucleus appears as the small purple mass). Capillaries range in diameter from 3-10 micrometres. Magnification: x7150 when printed at 10 centimetres across.