Premature Birth in Rats induced by Ethionine Injection

THE injection of pregnant rats with certain antimeta-bolites, such as ethionine, in sub-lethal doses, may result in resorption or stillbirth 1–4 . We wish to report the effect of smaller, repeated doses of ethionine on the course and outcome of pregnancy in rats. Daily subcutaneous injections, in the doses listed in Table 1, were given from the twelfth day of pregnancy until delivery. Control animals received saline injections. All injections were in a volume of 1 ml. The date of conception was established by the first appearance of sperm on vaginal smears.