Capillaries

They have a single layer of flattened endothelial cells. The capillaries' thinness promotes effective exchange between the lumen of the capillary and the surrounding tissue.

Pericytes

These cells wrap around the endothelial cells that line the capillaries and are a source of new fibroblasts.

Red Blood Cells

Capillaries are very tiny blood vessels: in capillaries whose diameters range from 3 to 8 μm, the red blood cells flow in a single file.