Chromosome lateral asymmetry: a sensitive assay for screening teratogenic agents.

Pregnant albino mice were administered (ip) embryotoxic doses of three individual teratogens: bromodeoxyuridine, hydroxyurea and mitomycin C on day 10 of gestation. Embryos were removed 4 hr later, a cell suspension was prepared and cultured in the presence of colcemid. Metaphase chromosome spreads were subjected to standard G-banding procedures, and the occurrence and frequency of lateral asymmetry (unequal banding of sister chromatids) was monitored. Embryotoxic levels of all three teratogens produced an increase in the number of asymmetries/karotype. For one of these (mitomycin C), the observed increase was dose-dependent.