Blood capillary with pericyte
Blood capillary cut open with empty lumen and pericyte. Pericytes, or Rouget cells, are adventitia cells that encompass the capillaries with their processes. They are probably contractile and able to phagocytize. The capillaries (also terminal vessels) are the finest ramifications of the arteries and veins and connect the arterial and venous vascular system. Their diameter is ca. 6 µm, which is a bit smaller than the erythrocytes, so that they have to deform when they pass. There are two types of capillaries: Continual capillaries (muscle type): They have a continuous endothelial lining and are completely encompassed by a basement membrane. Fenestrated capillaries: They have pores in their endothelial cells, where the vascular lumen is only seperated from the interstitium by the thin basement membrane. They occur mainly in the gastrointestinal tract and in endocrine glands. The capillaries are the location of exchange of oxygen, nutrients and metabolic waste products between the tissues and the blood circulation.