Fig. 6. Floorplate phenotypes in mol^-/- embryos are not only due to reduced Hh activity. (A,B) Lateral views of wild-type and mol^-/- embryos following overexpression of exogenous shh. There is some dorsal expansion (arrowheads) of foxa expression in the midbrain of both the wild-type and the mol^-/- embryo; however, foxa expression remains discontinuous and narrow along the CNS midline of the mol^-/- embryo (asterisks in B). (C,D) Transverse sections of embryos in which wild-type cells were transplanted into the prospective floorplate of a mol^-/- embryo (C) or mol^-/- cells were transplanted into the prospective floorplate of a wild-type embryo (D). foxa is shown in blue and transplanted cells are stained brown.