Fig. 5. The Pn-1 gene deficiency delays the onset of CGNP differentiation in the EGL. (A-H) Sections from P10 wild-type (A,C,E,G) and Pn-1-deficient mice (B,D,F,H) were immunostained for MATH1 (green; Hoechst, blue). In both groups, MATH1 staining is detected in the oEGL. The zone of MATH1-positive cells is enlarged in Pn-1-deficient mice. In addition, the intensity of the MATH1 staining increases at the cellular level. (I-L) Sections from P10 wild-type and Pn-1-deficient mice were immunostained for p27 (green; Hoechst, dark blue; overlap, light blue). The wild-type EGL is divided into two zones: the oEGL, with few p27-expressing cells, and the iEGL, expressing p27 at high levels (I,K). In Pn-1-deficient cerebellum, the p27-negative oEGL is approximately twice the width of the iEGL (J,L). (M,N) Sections from P10 wild-type and Pn-1-deficient mice injected with BrdU 1 hour prior to sacrifice were immunostained (BrdU, green; Hoechst, blue). Analysis of the wild-type oEGL (M) reveals regularly dispersed BrdU-positive CGNPs (arrowheads), whereas the proliferating CGNPs of Pn-1-deficient mice are closer to the external pial border (N). (O) The ratio of BrdU positive versus negative CGNPs is not significantly altered in mutants. (P) Mutant mice show a significant decrease in the fraction of p27-labelled CGNPs. ^*P<0.05 (Student's t-test). (Q,R) P10 cerebellar sections of Pn-1^+/+ and Pn-1^-/- mice immunostained for GFAP were analyzed by confocal microscopy. Pn-1^-/- Bergmann glia display higher GFAP levels together with an increased thickness of and larger endfeet (R) in comparison to wild type (Q). iEGL, inner external granular layer; oEGL, outer external granular layer. Scale bars: 80 µm in B for A-D; 20 µm in F for E-H; 40 µm in I for I-J and in Q for Q,R; 15 µm in K for K-N and in inset in Q doe insets in Q,R.