Abstract
Evidence that MC-induced dominant lethal mutations in early spermatids are attributable to chromosome aberrations was obtained through cytogenetic analysis of first-cleavage metaphases. Male mice were intravenously injected with 5mg/kg of mitomycin C (MC). These males were serially mated with females during 6 weeks after treatment. Chromosome slides were prepared from eggs collected from the ampulla. The maximum frequencies of chromosome aberrations in male pronuclei in the eggs were obtained in early spermatid stages. A close correlation between the frequency of eggs with chromosome aberrations and that of dominant lethal mutations at the same dose was observed.
