Histogenesis of the deep cerebellar nuclei in the mouse: an autoradiographic study.

In order to tag cells when they arise, pregnant mice were injected usually once or in some cases multiple times at a known time of gestation with tritiated thymidine. The offspring were killed and their brains prepared for autoradiography. Distribution of labeled cells was plotted using a drawing apparatus. Neurons of the deep cerebellar nuclei arise on gestation days 10-17. (Later periods were not studied.) Most neurons arise on gestation day 11. Many medium and small sized neurons arise after gestation day 11 with a limited number of small neurons observed to arise through the 17th day. Neurons for all parts of the complex arise at the same time, thus no gradients could be established.