EMBRYONIC DEVELOPMENT OF BLOOD VESSELS

摘要: The first step in the formation of blood vessels is emergence their inner lining cells, endothelial cells (EC). These then associate into tubular structures and other types, notably smooth muscle or pericytes, organize themselves around them to make vessel wall. Structural specializations such as tight junctions blood-brain barrier regionalized. adhesion molecules are acquired by differentiating EC. development new an uncommon physiological event adults. It occurs during corpus luteum placenta, wound healing regeneration tumorigenesis. latter phenomenon has been elected many groups for detailed morphological biochemical analysis. Various vivo vitro models have devised study this process. could be shown that do not arise de novo adult but derive from already established vessels. basement membrane surrounding capillaries breaks down; undergo mitogenesis migrate tumor under effect chemoattractive mitogenic factors (review Folkman, 1985). This process designated angiogenesis several growth identified with angiogenic properties. quiescent state normal most situations maintained through interplay between pericytes (Sato et al., 1990).