1.1.5.2　Blood vessels

The small arteries of the subcutaneous tissue and the large arteries deep in the dermis have three layers：intima，media，and adventitia.There are subpapillary vascular plexus and subdermal vascular plexus composed of arterioles and venules in the dermis.These vascular plexuses are roughly layered and parallel to the skin surface.There is a vertical blood vessel connection between the shallow plexus and the deep plexus，forming a rich anastomosis.The capillaries of the skin are mostly continuous，with continuous endothelium forming the wall of the vessels，and there are cell connections between adjacent endothelial cells.The venous system in the skin is generally parallel to the corresponding arterial system.The dermal vascular system is particularly abundant in the appendages.The above-mentioned structural characteristics of skin blood vessels contribute to nutrient metabolism and body temperature regulation.(https://www.daowen.com)