Two vascular systems, cardiovascular and lymphatic, maintain appropriate interstitial and intravascular fluid volume in the body. Each is endowed with innate physiologic response capabilities activated upon tissue or organ "damage." Chronic activation following pathologic assault, however, can contribute to pathogenesis. Three-dimensional visualization of vasculature in whole tissues using confocal microscopy is a valuable tool for examining cellular and architectural changes accompanying altered vascular function. The relative affinities of plant lectins for carbohydrate moieties present on luminal surfaces of endothelial cells can be used to characterize endothelium in distinctive physiologic and pathologic states. Perivascular cells that wrap around blood endothelial cells can be visualized using antibodies immunoreactive with alpha-smooth muscle actin. Similarly, lymphatic endothelial cells can be detected by antibodies immunoreactive to the hyaluronan receptor LYVE-1. Together, these approaches allow functional and morphological analysis of blood vasculature distinct from endothelial cells within the lymphatic vascular network and surrounding support cells.