Functional morphology of ductus venosus in human fetus

The morphology of region umbilical vein, umbilical sinus and ductus venosus of human fetuses have been investigated.

26 human fetuses between 20 and 40 weeks' gestation were examined by morphological methods. The umbilical vein, DV and the portal vein were obtained after termination of gestation. Tissue samples have been fixed in phormaldehyde solution (pH 7,2) and were embedded in paraffin. The paraffin sections (5-7 micro k) were stained with hematoxylin and eosin, silver impregnation by Bilchovski, orcein, pikrofuchsin. Measurement of the angle between ductus venosus and the portal vein was obtained with alidade.

Anatomical scheme of the region of umbilical vein, umbilical sinus and DV indicating two different patterns. The first: DV has situated into line with umbilical vein (22 cases). The second: umbilical vein has rotated before umbilical sinus, forming the turn in right (4 cases). The double-layer wall of ductus venosus (DV) contained the elastic, collagen and argyrophilic fibers. Around isthmus region of DV vasa vasorum and nervi vasorum have been found. The specific anatomical finding of the ductal isthmus was an accumulation of smooth muscle cells as intimal pillow, which were protruded into the vascular lumen. The double-layer wall of portal sinus (intima and adventitia) have been as the internal elastic membrane. The smooth muscle cells have been revealed in the walls, were not formed the tunica media at term 20-40 weeks of gestation. By the contrast the umbilical vein showed multiple, circularly running smooth muscle bundles. In this study, the ductal thickness was consistently bigger in the inlet than in the outlet. The tunica adventitia was greatest in the junction with the portal sinus and the inferior vena cava compared with the part arranged in the liver parenchyma. The wall thickness of the portal sinus and of the umbilical vein was significantly higher than of the duclal wall.

The vascular muscle-elastic cells of intimal hyperplasia ("intimal pillow") in wall of DV, probably, executes the role of the fortification of resistant behaviours of vessel wall in connection with DV and portal sinus with high hemodynamics load in this area. The maximum thickness of adventicia in the field of joints also witnesses an hemodynamic in favour of particularities. The angle between DV and left branches of portal vein in dominate cases was sharp and right that reflects the general regularity of architectonics of the vascular riverbed.