Fig. 5. Fgfr3-positive cells are unaffected in Pdgfa null spinal cords. Consecutive sections of newborn wild-type or Pdgfa knockout mouse cervical spinal cords were hybridised in situ with probes to Fgfr3 (A,B) or Pdgfra (C,D). The number of Pdgfra⁺ OLPs is strongly reduced in the Pdgf-A knockout (compare C with D) but neither the number nor the distribution of Fgfr3⁺ cells is changed noticeably (A,B). Again, we conclude that the Fgfr3⁺ cells and Pdgfra⁺ OLPs are different cells.