Abstract
1. In order to examine the teratogenicity of amniocentesis and the morphogenesis of resultant limb malformations, rat fetuses were subjected to a single amniocentesis during day 13 and 16 of gestation. 2. Gross malformations manifested were cleft palate and reductive malformations of extremities which are compatible to intrauterine amputations in human. They were predominant in degree and frequency in the group treated on day 15 of gestation, regard-less of the amount of amniotic fluid removed. 3. In the histological examination of the limbs, hemorrhages from the marginal blood sinus which were manifested 15 minutes after treatment caused necrosis of the mesenchymal tissue, and consequently intrauterine amputations or constriction rings resulted according to the extent of hemorrhages. Neither constriction by amniotic band and fibrous strings nor attachment of amnion to the limbs could be found in the process of limb malformations. 4. Experiments suggest that contraction of uterine muscle may well play an important role in the manifestation of hemorrhages from the marginal blood sinus.
