Figure 2.

[³H]Thymidine-birthdated granule neurons in the molecular layer of P10 cerebella from tPA^+/+ and tPA^−/− mice. (A) Autoradiography of a sagittal section of a tPA^+/+ mouse cerebellum showing relatively few birthdated migratory granule neurons still remaining in the molecular layer. Most granule cells have already moved into the internal granule layer beneath the Purkinje neurons. (B) Autoradiography of a similar section from a tPA^−/− mouse cerebellum showing many more birthdated migratory granule neurons still in the molecular layer. (Bar = 50 μm.)