ABSTRACT
Pregnant animals were treated with five chemical teratogens and a teratogenic dietary regime. Embryos were examined for chromosome changes in squash or ‘direct method’ preparations at various times after administration of the teratogen.
Embryos from rats treated with a teratogenic dose of nitrogen mustard or chlorambucil showed a peak of less than 20 % metaphase figures with chromosome abnormalities. Streptonigrin produced less than 10 %. The maximum chromosome abnormalities appeared within 24 h after injection and almost all abnormal metaphase figures disappeared within 48 h after injection.
Other chemical teratogens such as hydroxyurea injected into pregnant rats and thalidomide fed to pregnant rabbits produced no detectable chromosome abnormalities in the embryos. There were also no abnormal metaphase figures detectable in rat embryos after maternal exposure to a riboflavin-deficient diet.
