Transplacental effects of ethylnitrosourea in a nonhuman primate, Erythrocebus patas

A breeding colony of the Old World monkey Erythrocebus patas, an African species, has been established to study transplacental carcinogensis in a representative primate species. ENU was administered by repeated iv injections to pregnant females and to juveniles of both sexes. Repeated doses of 0.1 mmole/kg body weight per injection, given at 14-day intervals, are tolerated without apparent signs of toxicity by fetal and by pregnant and nonpregnant adult or juvenile monkeys. The internal can be reduced to 7 days, at least during the latter two-thirds of pregnancy. Large single doses (1.0 mmole/kg) are tolerated by pregnant females but are frequently abortifacient. These doses produce acute cytolytic damage to the cells of the periventricular germinal matrix in the fetal brain. Studies with [14C]ethyl-ENU indicate that there is no placental barrier to this carcinogen. As of December 1975, no tumors had been observed.