The morphogenesis of developmental defects induced by amniotic sac puncture was studied at the gross and microscopic levels. In fetuses recovered from 15 min to 48 h after amniocentesis, a pattern of hemorrhagic lesions, excessive accumulation of interstitial fluid, followed by tissue necrosis and leading ultimately to the reduction or amputation of distal limb segments and morphological changes in the head, was observed. These changes were indicative of venous stasis, hypervolemia and embryonic oxygen deficiency. Γntrauterine compression of the fetus and the obstruction of the fetomaternal circulation were considered to be the primary etiological factors in amniocentesis-induced anomalies which included hemorrhagic lesions, limb reductions and amputations, deformities of the head and abdominal regions, generalized edema and postural moulding