Delayed teratogenic effect of methylmercury on hepatic cytochrome P-450-dependent monooxygenase systems of rats.

Hepatic cytochrome P-450-dependent monooxygenase systems were depressed in adult male rats which had been exposed prenatally to methylmercury. The effect was not seen in immature male or female rats or in adult female rats. This latent teratogenic effect of methylmercury appeared only when exposure occurred during early fetal development. These studies demonstrate that the expression of a chemically induced teratogenic effect may be considerably delayed in the rat and that the stage of development of the fetus at the time of exposure to the chemical agent may be a determining factor.