The embryolethal and teratogenic effects of cyclophosphamide on mouse embryos

Pregnant mice were injected once with 10 or 20 mg/kg cyclophosphamide. A large embryolethal effect was induced by treatment on the 3rd and on the 8th and 9th days of pregnancy. Mortality was probably due to a direct effect of cyclophosphamide on the embryos. Limb malformations were induced at a later stage; therefore it appears that embryolethality and teratogenicity are separable processes. The anomalies consisted of synostoses, retardation of ossification, and poly‐ and oligodactyly. Polydactyly was induced at an earlier stage than oligodactyly.