The structure of the cusps of valves in the human foetal great saphenous vein.

The study was performed on 110 great saphenous veins in human foetuses of both sexes aged 9 to 37 weeks. The earliest well-shaped valves were observed in foetuses aged 13 weeks. In these foetuses the number of valves varies from 2 to 7. Consecutive microscopic sections revealed that the developing valves at their origin present thickening of the endothelium which is continuous into the cusps of the valves. The bicuspid cusps are crescent-shaped and both surfaces are lined by endothelium.