Movements of mouse fetuses in early stages of neural development studied in vitro.

The transplacental perfusion method enables the in vitro maintenance and close observation of live mouse fetuses under conditions free of maternal influences. In the present study, this method was used to detect spontaneous movements of mouse fetuses in early developmental stages. When mouse fetuses at embryonic day (E) 12.5 were isolated together with the uterus and were maintained in vitro, they displayed periodic body movements that occurred every few minutes. Fetal movements were abolished after the application of drugs that depress neural activities. The present results obtained in in vitro mouse fetuses suggest that fetal movements and neural activities may be present during the early stages of motor system development and may play a role in the normal maturation of the motor systems.