Early foetal thrombosis induced by thalidomide in mouse: possible explanation for teratogenicity.

Mouse foetuses were treated by Thalidomide on days 11-12 in order to verify whether the drug would induce blood abnormalities leading to circulatory troubles. About 18% of the treated foetuses showed both severe limb haemorrhages on day 14, and obvious alterations of the nucleated red blood cells of vitelline origin. These blood abnormalities, occurring suddenly during the well-known 'critical stage' of foetal development, could be responsible for circulatory blocks leading to necrosis.