[The loop-like growth of the vessels and the embryonic morphogenesis of the human intraorganic circulatory system].

Development of the vascular bed during embryogenesis in man occurs through loop-like growth of vessels appearing as multiplication, integration, and morphofunctional transformation of vessel loops. Growth of loops provides for the establishment of transport vessels in organs and tissues, and loop integration leads to the establishment of microcirculation with the appearance of connecting and major capillaries, from which true capillaries and capillary networks are formed. Precapillary arterioles and postcapillary venules can be identified topographically in the capillary networks. Formation of blood microcirculation system is complete when morphofunctional arrangement of integrated and nonintegrated loops takes place with the appearance of arterioles and venule collaterals and arterio-venule anastomoses in the vascular network.