Fig. 4. Rescue of neural tube patterning in Ftm^-/- embryos by abrogating Gli3 function. Shown are immunohistochemistry data at stage E11.5 mouse embryos from four different genotypes. (A-C) In wild-type embryos, MNR2 (A) is expressed lateral to Nkx2.2 (B), which is expressed adjacent to the floor plate. Furthermore, Pax2 is expressed in the dorsal region of the neural tube (C). (D-F) By contrast, Ftm^-/- embryos show a strong reduction of MNR2-positive cells (D) and Nkx2.2-expressing cells (E). Expression of Pax2 is expanded into the most ventral part of the neural tube (F). (G-I) In Ftm^-/-; Xt/+ embryos, the number of MNR2-positive (G) and Nkx2.2-positive (H) cells is increased, but these cells still cross the midline. Pax2-expressing cells are expanded into more ventral parts within the neural tube, but there are fewer cells crossing the midline (I). (J-L) In Ftm^-/-; Xt/Xt embryos, MNR2-expressing (J) and Nkx2.2-expressing (K) cells are absent from the midline and located in two lateral distinct domains. Pax2-expressing cells (L) seem to be completely restored.