Fig. 4. Both Ift88^hypo and Ift52^hypo mutant embryos have ventral spinal cord defects. (A-D) In the wild-type spinal cord, (A) Shh is expressed in both the notochord and floorplate, (B) Nkx2.2-expressing cells are adjacent to the floor plate, (C) Isl1/2-expressing motoneurons are dorsal to Nkx2.2 cells, and (D) Pax6 is expressed weakly in dorsal neural progenitors and strongly in the intermediate regions in the spinal cord. (E-L) In both IFT mutants (E,I), the Shh expression in the floorplate is absent, (F,J) a reduced number of Nkx2.2 expressing cells are present in the ventral midline of the spinal cord, (G,K) Isl1/2-expressing cells are found scattered in the ventral midline, and (H,L) cells strongly expressing Pax6 are found scattered ectopically in the ventral most region of the spinal cord. Red arrows indicate the ventral most part of the spinal cord.