MMT was administered to female Long Evans rats by gastric intubation at dose levels of 5, 10 20 and 40 mg/kg/day from Day 6 to 15 of gestation. All rats were sacrificed at Day 21 of gestation, and the fetuses evaluated by conventional teratological procedures for malformations of the external form, soft tissues and skeletons. Parameters evaluated include: maternal body weight, in-life physical observations, pregnancy and mortality rates, and reproduction data (implantations, number of fetuses, resorptions); fetal viability indices, weight, crown-rump distance and normal ossification variations; and teratological parameters included fetal external (necropsy) examinations, soft tissue and skeletal examinations.