Fig. 4. Thinned INL and IPL in retinae lacking Pcdh- proteins. (A) Diagram of conditional Pcdh- inactivation alleles. Each Pcdh- protein is encoded by an mRNA, comprising one of 22 variable exons and the three constant `C' exons. In Pcdh- ^fdel, loxP sites flanking the entire Pcdh- locus result in deletion of all Pcdh- genes upon Cre-mediated recombination. In Pcdh- ^fcon3, loxP sites flank the final C3-GFP exon, resulting in truncated forms of Pcdh- proteins. In both alleles, GFP is fused to the C terminus of the C3 exon. (B-G) Sections from P18 control and Pcdh--deficient retinas, labeled with DAPI or anti-synaptophysin to highlight nuclear and synaptic layers, respectively. Retinal lamination is normal, and OPL and ONL are normal in thickness but IPL and INL are markedly thinned in mutants. (H) Quantification of nuclear and plexiform layer thickness in control (black), Chx10-Cre; Pcdh- ^fdel/fdel (white) and Chx10-Cre;Pcdh- ^fcon3/fcon3 (gray) retinas at P18. Bars show mean±s.e.m. from three or four animals of each genotype. ^**P<0.01, ANOVA and post-hoc Tukey test. (I) Quantification of retinal cell types in Pax6-Cre;Pcdh- ^+/fcon3 (black) and Pax6-Cre;Pcdh- ^fcon3/fcon3 (gray) P18 retinas. Bars show mean±s.e.m. from six to eight animals of each genotype. PR, photoreceptors by Po-pro1; HZ, calbindin+ horizontal cells; BP, Chx10+ bipolar cells; AC, Pax6+ amacrines; RGC, Brn3a+ retinal ganglion cells; MG, Sox9+ Müller Glia. Other abbreviations as in Fig. 1. Error bars indicate s.e.m. ^***P<0.0001, Mann-Whitney non-parametric test. Scale bars: 50 µm.