Effects of Ethylenethiourea upon Developing Brain and Limb Buds in the Rat

Abstract

Single oral dose of 50, 100, or 200 mg/kg of ethylenethiourea (ETU) was given to Wistar-Imamichi female rats on day 12 or 13 of pregnancy. These treatments resulted in high incidences of brain and digit anomalies in the term fetuses. For induction of digit anomalies, treatment on day 13 of pregnancy was most effective. In 200 mg/kg group, all the digits were absent in 81% of the forelimbs examined. The neural tube and forelimb buds were periodically collected and examined for histological alterations after maternal treatment with 100 mg/kg of ETU on day 12 of pregnancy or with 200 mg/kg of ETU on day 13. In the neural tube, necrotic cells first appeared 12 hours after the treatments. By 24 hours after the treatments, cell necrosis was extended throughout the neural tube and the neural canal was filled with cellular debris. Also in the forelimb buds, an extensive mesenchymal necrosis was observed 24 hours after treatment with 200 mg/kg of ETU on day 13 of pregnancy. On the other hand, no histological alterations were detected after 100 mg/kg of ETU on day 12 of pregnancy.