Function: selective permeability: exchange of fluids, gases, and metabolites and waste products between blood and tissues; synthetic, metabolic and antithrombogenic activities.
Location: muscle, lung, central nervous system {Ne/nerv.html}.
Composition: endothelial cells contain numerous pinocytotic vesicles, pericytes are enclosed by a basement membrane.
Location: endocrine glands, sites of fluid and metabolite absorption: renal corpuscles, intestinal tract, and gallbladder.
Composition: endothelial cells contain fenestrations, 80-100 nm in diameter, those provide channels across the capillary wall, pericytes are enclosed by a basement membrane.
Location: liver, spleen, and bone marrow.
Composition: endothelial cells with unusually wide gaps between them, partial or total absence of basement membrane.