Fig. 9.

Math1-cre::Ctnnb1(ex3)^Fl/+ cerebella displayed severe histomorphological abnormalities similar to those of cerebella of Math1-cre::Apc^Fl/Fl mice. At P0, the sizes of the cerebella were still comparable between Math1-cre (A) and Math1-cre::Ctnnb1(ex3)^Fl/+ (B) mice, but the EGL was already thinned out in rostral parts of Math1-cre::Ctnnb1(ex3)^Fl/+ cerebella (B, arrows in inset) with significantly fewer granule neurons per mm EGL (C). At P7, the overall size of the mutant cerebellum was reduced (D and E), the EGL was severely diminished in rostral parts of the cerebellum (F, G, and I, arrows), and Purkinje neurons were diffusely distributed within the cerebellar cortex (I, arrowheads). Compared to Math1-cre cerebella (H), Ki-67 labeling was restricted to very few cells in the Math1-cre::Ctnnb1(ex3)^Fl/+ EGL (J and K). At P21, Math1-cre::Ctnnb1(ex3)^Fl/+ cerebella (M) were much smaller than those of controls (L). No granule cell layer was visible in rostral parts of the knockout cerebellum (M), and caudal parts displayed clusters of ectopic granule neurons that were stuck within superficial parts of the molecular layer (M, inset, arrowheads; N). All panels represent stainings from sagittal sections. EGL, external granule cell layer; IGL, internal granular layer; ML, molecular layer; PCL, Purkinje cell layer. Enlarged views of boxed areas in panels D and E are presented in other panels, as indicated.