The blood of the fetus is supplied to the placenta usually by two umbilical arteries; it returns to the fetus through one umbilical vein which is formed on the placental chorionic plate from several tributaries and runs in the umbilical cord accompanied by the two arteries. This study is an attempt to determine whether particular tributaries of the umbilical vein anastomose within the placentaproximal to the formation of the umbilical vein. The study has been carried out by the corrosion method on human placentas coming from normal full-term pregnancies. To arteries - chemohardenable Plastogen G stained in red was injected, whereas to each tributary of the umbilical vein - Plastogen G stained in other colours (blue, green, yellow, brown) was injected in order to differentiate between the areas of drainage by particular tributaries of the umbilical vein. It was established that filling each of the tributaries of the umbilical vein with a different colour of Plastogen G yields a division of the placenta into 'venous segments', undescribed so far, varying in number from 2 to 5. No anastomoses between the veins of particular 'segments' have been found. Furthermore, it is shown that 'venous segments' do not overlap with 'arterial segments'.

Keywords: human placenta, placental veins, Anatomy, corrosion casts