Figure 4

Cell type-specific expression of cadherins revealed by in situ hybridization (dark purple precipitate). A, B: Expression of protocadherin-7 (PCDH7; A) and protocadherin-1 (PCDH1; B) in the ganglion cell layer (GCL) at postnatal day 60 (P60). Note the positive large ganglion cells (large arrowhead in A, 19 μm diameter; large arrowhead in B, 26 μm; small arrowhead in B, 20 μm), a negative large ganglion cell (large arrow in B, 25 μm), and a positive, putative small ganglion cell (small arrow in A, 11 μm). The elongated cell in the nerve fiber layer (NFL, small arrow in B) probably represents an astrocyte. Panel B shows the area boxed in Fig. 2C. C-E: Putative displaced ganglion cells adjacent to the inner plexiform layer (IPL; arrows) express cadherin-6 at P13 (CDH6; C), protocadherin-10 at P25 (PCDH10; D), and protocadherin-9 at P60 (PCDH9; E). Cells are identified as ganglion cells based on their large somata (13 μm, 15 μm, and 14 μm, respectively) and nuclei (10 μm, 11 μm, and 12 μm, respectively) and the large gaps occupied by them between neighboring amacrine cells. F, G: Cadherin-20 expression by putative Müller glia at P13 (CDH20, arrowhead in F) and PCDH9 expression by putative bipolar cells (arrowhead in G). The small arrow marks a positive amacrine cell. Panel G shows the area boxed in Fig. 2F. H: A large horizontal cell expressing protocadherin-1 at P60 (PCDH1; arrow). I: Photoreceptor cells throughout most of the outer nuclear layer (ONL) express cadherin-8 at P60 (CDH8; arrowhead). Cell nuclei are shown in light pink color (A, B, F-I) or light blue color (Hoechst nuclear counterstain; C-E). The different layers of the retina are indicated on the right-hand side of each row of panels. Other abbreviations: INL, inner nuclear layer; OPL, outer plexiform layer. Scale bars are 20 μm.