Twelve 60-day-old female Mus musculus were divided into two groups on the 7th day of pregnancy: treated group--1 mg isotretinoin per kg body weight, dissolved in vegetable oil, was administered from the 7th to the 13th day of pregnancy; control group--vegetable oil in equivalent volume was administered orally for the same period. On the 16th day of pregnancy, the females were sacrificed, the fetuses were removed and their heads amputated.