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We examined 100 selected placentas concerning architecture and distribution of the vessels of the chorionic plate. The eccentric insertion of the umbilical cord as well as the mixed type of distribution of the chorial arteries and equal areas of arterial blood supply were found to be most frequent. In no case the anastomosis of Hyrtl was absent. A marginal and a very eccentric cord were more frequent in combination with a mixed and magistral type of distribution of the vessels that the lesser eccentric and the central type of insertion. There was no significant correlation between insertion of the cord and the infants' birth weight. Arteries pass over the veins when they cross. Serial sections of 15 crossing vessels have been examined, one specimen was reconstructed graphically. When crossed by major arteries the veins bypass below whereas small arterial branches override larger veins not affecting their course. The cross-like vessels are wrapped up in connective tissue and anchored to the chorion plate. There are equivalents in the morphology of the vessels of the chorion and the retina. Both vessel systems are embedded in hollow bodies exposed to an inner pressure, however, sharing a common media, the crossing artery and vein of the retina represent a more intense anatomical unity. The connective mesenchymal frame of the crossing vessels of the choroin plate, the thickened arterial wall-segments and the venous wall-sectors let functional valves suspect as is known from other areas of blood supply.

The mechanisms of the development of knots in the umbilical cord are described. The different types of knots are enumerated. The causative factors for the development of a knot in the umbilical cord are discussed. This paper is based on a statistical evaluation of the deliveries of the Maternity Hospital of the University of Bonn from 1967-1970. These data have been adopted from the Author's M.D. Thesis of 1972. At the end of the paper the comparative anatomy of the umbilical cord complications is discussed.

A series of 549 not selected placentas and umbilical cords were examined to show the influence of the different development of the umbilical cord structure on the umbilical cord perfusion and the course of parturition. For this purpose the quantity of Wharton's jelly, the spiraling of the umbilical vessels as well as the length of the cord are defined. At the same time anatomical pecularities and complications like umbilical cord torsions and true knots are considered. To judge the decisive condition of the newborn and with that the course of parturition, the pH-value of umbilical artery blood is determined. The analysis results that umbilical cords with much Wharton's jelly and with spiraling vessels are converted into an association with extremely better value than those with little jelly and less spiraling vessels. Short and rich jellied umbilical cords show a significantly lower incidence of loops around the fetal body. A similar trend can be demonstrated for umbilical cords with strong spiraling arteries. Rare phenomena like velamentous insertion, haematomas, edemas and true knots of the cords etc. proved to have no influence on the course of parturition in our relatively small examination series.