ABSTRACT
This chapter presents an overview of the microvascular bed and how it appears to participate in immune responses. The dermal microvascular unit is composed of an endothelial cell tube surrounded by basement membrane material, 1 to 3 µm thick, in which are embedded contractile cells. The upper and lower horizontal plexuses are the physiologically important zones in the skin. The bulk of the microcirculation resides in the papillary dermis 1 to 2 mm the epidermal surface. The capillary loop arises from a terminal arteriole in the horizontal papillary plexus. In the deep dermal venules, the collagen fibrils are distributed individually throughout the vascular wall parallel to the long axis of the vessel. As people knowledge of immunology grows, it should be possible to incorporate the microanatomical features of the vessels into their relevant associated immunological mechanisms. Smooth muscle cells and pericytes comprise the contractile elements of the microvascular wall.
