[Embryonal histogenesis of endothelium].

Development of the mammalian vascular system is characterized by recapitulation of many morpho-functional signs peculiar to certain ancestral forms, as well as by certain aromorphous reorganizations reflecting in histogenesis of endothelium. Prior to the period of the common blood circulation in the mammalian embryos, the endothelium is developing within the endomesenchyme constructed by cells of a peculiar - endothelial - germ, but not of the endomesenchymal cells, as numerous investigators consider. The endothelium is developing as a capacitance tissue which presents by itself an epitheliomorphous duplex selective membrane, functionally connected with blood, tissue fluid and lymph in order metabolism and other functions of the organism's cells and tissues can be performed. Increase in cell number and their proendothelial derivatives at pretissue, tissue and hemoendothelial levels and successive union of recapitularities with the same name at the formation of the endothelial vessels add certain essential features to histogenesis of the endothelium and to its normal reactions. Polymerization and union of the recapitularities with the same name are the ways of integration; they are important ingredients of hereditarily determined differentiation. The latter is realized in the development of hemoendothelial offsprings which appear after the common blood circulation is started. The endothelial genesis in its capacitant form is complemented with blood cells incorporated, the means which is subjected to certain essential evolutional reorganizations. In its turn, this results in appearance of the double tissue hemoendothelial complex possessing features of an elementary organ.