Immunocytochemical detection of 5'-bromodeoxyuridine incorporation in the central nervous system of the mouse.

In order to label postmitotic neuroblasts, pregnant mice received a single pulse of 5'-bromodeoxyuridine (BrdU) between embryonic days E11 and E17. Young adult offspring were stained for BrdU using a monoclonal antibody and the peroxidase-antiperoxidase method. The distribution of immunoreactive nuclei was very similar to the [3H]thymidine data reported in the literature. The pattern of labelled nuclei after injection at different embryonic ages followed the spatiotemporal gradients described for cortical and hippocampal neurogenesis. Lightly and heavily labelled nuclei, probably representing subsequent postmitotic generations, were distinguished in BrdU-immunoreacted preparations. These data indicate that BrdU can be used to map neuronal birthdates.