[Demonstration of prenatal maternal influences by embryo transplantation in mice]

A comparison between inbred C57BL/6 Mice either transferred at an early developmental stage into the uterus of a hybrid female and then nursed by this mother, or only fostered to such a mother at birth, is performed in order to differentiate between uterine and postnatal maternal effects. At 21 days of age, animals from embryo transfer are heavier and display a greater amount of locomotor activity during a 48 hr period in a seminatural environment than crossfostered subjects. On the other hand, the L.D. distribution of this activity is not affected by the differences in development environments. The interest of such a methodology for the genetic analysis of behavioural differences related to differences in the environment during ontogeny is discussed.