Fig. 8. Improperly patterned RPE differentiates into a NR-like structure in Otx1^-/-; Otx2^+/- mice. Paraffin sections at equivalent axial levels through the eye of E17.5 wild type (A,D,G) and Otx1^-/-; Otx2^+/- mice (B,C,E,F,H,I). C,F and I are high power views of the ectopic neural retinas illustrated in B,E and H, respectively. Sections were immunostained with antiserum against Tuj1 (A-C), Ph-H3 (D-F), and Islet1 (G-I). Note the presence of Tuj1- and Islet1-positive differentiated neurones not only in the vitreal surface of the NR of both wild-type and mutant embryos but also on the sclera side of the ‘ectopic’ NR (arrowheads in C and I). Mitotic Ph-H3-labeled nuclei are located at the vitreal surface of the ‘ectopic’ retina (arrowheads in F). egc, ectopic ganglion cells; enr, ectopic neural retina; gcl, ganglion cell layer; L, lens; nr, neural retina; pe, retinal pigment epithelium; sc, sclera. Bar: 400 µm but C,F,I, 250 µm.