Title: Small artery and vein (submucosa colon, human)
Immunochemical staining of smooth muscle actin with anti-α-Sm actin-Alkaline Phosphatase conjugated antibodies counterstained with hematoxylin, human. Small artery (1) possesses a regular muscular wall (red) while a small vein (2) stuffed with erythrocytes displays irregular red smooth muscle bundles. (3) Venules with less regular arranged actin-positive SMC. (4) Capillary with pericytes.
Background: Staining for smooth muscle actin facilitates the discrimination between arterial vessels and venous ones. Smooth muscle cells as well as pericytes react positively. The vascular wall is composed of an inner tunic (intima composed of an endothelium-basal lamina /some connective tissue/internal elastic lamina), a middle tunic (media composed of smooth muscle cells/elastic fibers-lamellae, collagen fibers), and an outer tunic (adventitia composed of connective tissue/supplying vessels and nerves).
Segmental differentiation of the body vasculature implicates that in certain areas or organs different features of the tunics are found accentuated, or reduced, or omitted, or even introduction of additional structures occurs. (Partly adapted from Yale http://medcell.med.yale)
Keywords/Mesh: vascularization, blood vessels, artery
capillary, venule, vein, pericytes, smooth muscle, actin, histology, POJA collection