Fig. 4. Localisation of RPE markers in Otx-deficient mice. Consecutive sections through E9.5 OV (A-F) or E12.5 OC (G-O) of wild-type (A,D,G,J,M), Otx1^+/-; Otx2^+/- (B,E,H,K,N), and Otx1^-/-; Otx2^+/- mice (C,F,I,L,O) were immunostained with an antiserum against OTX2 (A-C,G-I) and MITF (D-F) or hybridised with digoxigenin-labelled probes for Mitf (J-L) and tyrosinase (Tyr; M-O). Note how in mutant mice the abnormal distribution of MITF extends through the OV (D-F) overlapping with the ventrally diffused expression of OTX2 (A-C). Note the abnormal folding of the OC in Otx1^+/-; Otx2^+/- and Otx1^-/-; Otx2^+/-mutants (J compared with K,L). The outer layer of the OC is thicker (inset in G-I) and lacks pigmentation and expression of Mitf (K,L) and tyrosinase (Tyr; N,O). Note that in mutant mice small patches of RPE co-express OTX2, Mitf and tyrosinase (arrows in H,I,K,L,N,O). enr, ectopic neural retina; lv, lens vesicle; nr, neural retina; ol, outer layer; os, optic stalk; ov, optic vesicle; pe, retina pigment epithelium; pnr, presumptive neural retina. Bar: 200 µm (A-F), 300 µm (G-O).