Fig. 2. Homozygous Gli2^lzki/lzki embryos have defects in ventral spinal cord development at E10.5, similar to Gli2^zfd/zfd mutants. In Gli2^lzki mutant spinal cords (G-L), the floor plate cells that express Shh and HNF3ß are lost (G,H). Nkx2.2-expressing V3 interneurons are greatly reduced in number(I). Loss of floor plate also results in a ventral expansion of Islet1/2- (J) and Pax6- (K) expressing cells. Pax7 expression is unaffected (L). White arrowhead represents ventral limit of Pax6 or Pax7 expression domain. (M,N) E10.5 spinal cord stained with an Isl1/2 antibody for motoneurons. The floor plate fails to develop in Gli2^lzki/zfd embryos, and motoneurons occupy the ventral midline. (O,P) Hematoxylin and Eosin staining of E12.5 spinal cord. The notochord (indicated by black arrow) fails to regress in Gli2^lzki/zfd embryos. (Q,R) E12.5 Gli2^lzki/zfd embryos have smaller lungs without an accessory lobe. The margins of the spinal cord and spinal canal are outlined by broken white lines. The margin of lungs is outlined by broken black lines. Scale bar: 100 µm in A-E,D-K; 78 µm in F,L; 130 µm in M,N.