Metabolic fate of ethylenethiourea in pregnant rats.

Metabolic fate of ETU was investigated in the rats administered orally 100 mg/kg of C14-ETU on the twelfth day of gestation. ETU was absorbed readily from the gastrointestinal tract and passed away from the whole body tissues including the fetus rapidly. Only the exception was the thyroid gland and the radio-activity was accumulated in the gland. Most of the administered activity (80.2%,4,5-C14-ETU) was eliminated into the urine in 24 hr and the tissues (including the fetus) levels of radioactivity from 2-C14-ETU reached maximal within 2 hr and fell down to negligible levels by 24 hr. Radiocarbon(s) of 4,5-C14-ETU was expired as radioactive carbon dioxide and was incorporated into the serum and fetal cell constituents (crude protein fraction), but that of 2-C14-ETU was neither expired or incorporated into the cell constituents. From the fetus extract ETU and several radioactive metabolites were detected.