Figure 3

Self-renewal of neural progenitors in cerebellum was not abrogated upon Sox9 inactivation as revealed by immunofluorescence staining on cerebellar sagittal sections. (A-D) Expression of the neural stem cell marker Sox2 was not lost in the Sox9-null cerebellum during late gestation under both En1-Cre and Pax2-Cre mediated Sox9 inactivation. In both groups, scattered signals were observed in the VZ and the prospective white matter, while the EGL displayed the strongest signal which corresponded to the actively proliferating granule cell precursors. (A’) and (B’) showed enlarged view of the VZ. (E-J) Quantification of mitotic activity at the VZ by double pulses of BrdU at either E16.5 (E-F) or E18.5 (G-H) did not reveal any difference in the proliferation of VZ neural progenitors between control and the Pax2-Cre induced Sox9-null mutant. The number of BrdU-labeled cells in the VZ was divided by the total number of VZ cells to obtain the labeling index (I-J). No statistically significant difference was observed using the Student’s t-test at both E16.5 (I; p = 0.4906) and E18.5 (J; p = 0.1633). (K-R) In addition, we did not observe any alterations in the expression of proliferation associated markers PCNA and Ki67 upon Sox9 inactivation. (A’-Q’) are the enlarged view at the VZ of (A-Q). The error bars indicate standard deviations. Abbreviations: egl, external granular layer; pcl, Purkinje cell layer; rl, rhombic lip; vz, ventricular zone. Scale bars: A-S: 100 μm; A’-B’, G’-H’, K’-L’, P’-Q’: 50 μm.