Fig. 2. Pax2 and Pax6 activity is not required for the regionalization of the OV. Immunohistochemistry of serial, 6 µm sections at E12.5 (A-H) and E10.5 (I-P). In the wild-type eye at E12.5, Mitf expression is confined to the RPE and some cells in the dorsal optic stalk (A, arrowhead). By contrast, Otx2 is expressed in the RPE and the dorsal optic stalk, with a sharp, distal-proximal gradient in the distal NR arrowheads, (B). Chx10 is restricted to the NR (C) and Pax2 mainly to the optic stalk (D, arrowhead). (E) At E12.5, Mitf expression in the Pax6^-/- mutant eye is confined to the distal tip of the OV. Otx2 is expressed highly in the same region (F) but less in the medial portion of the OV where Chx10 is expressed at a high level (G). (H) The proximal region of the Pax6^-/- OV expresses Pax2 strongly (p), expression in the medial region is at a lower level (m) and the distal region is Pax2 negative (d). (F, inset) In the Pax6^lacZ/lacZ OV, the ß-gal expression is restricted to the distal and the medial regions, which reflects the distribution of ß-gal expression in the RPE and NR in Pax6^lacZ/+ eyes (B, inset). Broken lines in E-H indicate the borders between d, m and p regions. The comparison of the patterning of E10.5 wild-type (I-L) and Pax2^-/- eyes (M-P) revealed in both genotypes the unchanged expression of Mitf (I and M) in the RPE and optic stalk, of Otx2 (J and N), which is found in both phenotypes in the RPE and optic stalk, gradually in the NR and some cells of the optic stalk, as well as the unchanged expression of Chx10 in the NR (K and O) and of Pax6 throughout all eye components (L and P). (I, inset) Expression of Pax2 in the wild-type optic disc and the missing Pax2 expression in the Pax2^-/- eye (M, inset). le, lens; os, optic stalk; nr, neural retina; rpe, retinal pigmented epithelium.

Return to article