Axial abnormalities following disturbed growth in mitomycin C-treated mouse embryos.

Primitive-streak and early-organogenesis-stage mouse embryos were treated with Mitomycin C (MMC) by intraperitoneal injection of pregnant females. Skeletal preparations of newborn pups were made and the axial skeleton examined. The treated animals showed a high incidence of:- (1) changed vertebral numbers, (2) malformation of the vertebral column, (3) changed rib numbers and (4) rib abnormalities. These skeletal disturbances tend to be located more posteriorly with later MMC treatment. There is regional variation in the susceptibility of vertebrae to abnormal development. Extra elements may occur in any region of the spinal column and several unique combinations of numbers are reported. The possible origin of these abnormalities and their similarity to some human syndromes is discussed. It is suggested that they may be the consequence of altered growth profiles in interacting tissues during the restorative growth following MMC treatment.