Figure 5

RBP-J deletion does not affect the differentiation of cerebellar cell types. (A-D) At E18.5 neuronal differentiation is occurring normally in all mutants as shown by similar staining for betaIII-tubulin. (E,G) In P7 cerebella of controls (E) and Notch-inactivated mutants (G), cells of the outer EGL are proliferating and stain positive for PCNA. (F,H) In Ptc1^lox/lox; Math1-Cre and Ptc1^lox/lox; RBP-J^lox/lox; Math1-Cre cerebella, proliferating cells populate the whole EGL, including the inner region. (J,L) Pax6, a marker for granule neurons, indicates differentiation is initiated in Ptc1 deleted brains (J) and Ptc1^lox/lox;RBP-J^lox/lox;Math1-Cre cerebella (L). (I,K) RBP-J deleted cerebella (K) show normal differentiation of GNPs compared to controls (I) at P7. (M-P) At P21 mature neurons in the EGL express NeuN while Bergmann glia express glial fibrillary acidic protein (GFAP). Bergmann glial fibres are aligned in parallel, spanning the ML (arrows). In RBP-J deleted cerebella (O) neither neuronal nor glial development appears impaired compared to controls (M). Ptc1 deleted cerebella have an IGL with NeuN-positive differentiated neurons; however, NeuN-positive cells are also present interspersed in the expanded EGL (T, tumour). In addition, Bergmann glia in Hh-activated cerebella appear disorganised without parallel alignment of their fibres (N). The effect of Ptc1 deletion on neurons and Bergmann glia cannot be overcome by Notch inactivation (P). (Q,S) Purkinje neurons marked by Calbindin are organised in a single layer between the ML and IGL of control (Q) as well as RBP-J deleted cerebella (S). (R,T) Hh activation results in disorganisation of the Purkinje cell layer (PL) (R), which is not changed by additional RBP-J deletion (T). Images in each panel were taken at the same magnification and nuclei were counterstained with DAPI. Scale bars represent 50 μm.