The umbilical arteries in man anastomose close to the placenta. Bruin ('01) describes such an anastomosis in the ox a t about the middle of the umbilical cord.
This report is based upon the study of 70 full-term normal human placentas with the umbilical cords attached. I n order to better show the vascular topography the umbilical arteries were prepared for study in the following fashion. The arteries, when injected with vinylite, placed in a 10% solution of formalin to permit the vinylite to harden and then corrosion specimens were prepared by immersing the entire placenta in a strong aqueous solution of HC1. Ninety-six per cent of the specimens had anastomosis of one type or other, two umbilical cords were without anastomosis, and one specimen had a single umbilical artery. I n 90% of the cases the anastomosis was located within 1.5 em of the placental end of the umbilical cord. Measurements made immediately following injection demonstrated that anastomoses varied in length from 1.5 to 2.0 cm and in outer diameter from 1.0 to 1.5 mm. There mere three basic anastomotic relationships: in 72%, the stems of the umbilical arteries were connected by an intermediate branch (see fig. 1A) ; in 18%, the anastomosis was between the stem of the umbilical artery and a branch of the other (see fig. 1B) ; in 10% there was an area of fusion of the two nm. bilical arteries (see fig. IC). Anastomoses betwem the branches of the umbilical arteries have not been observed, therefore 1