Fig. 4. Different populations of Fgfr3⁺ and Pdgfra⁺ cells in the newborn spinal cord. We hybridised sections of P2 mouse cervical spinal cord simultaneously with a DIG-labelled Fgfr3 probe together with an FITC-labelled Pdgfra probe to visualise OLPs. The Fgfr3 signal (red) was visualised with rhodamine-tyramide reagent and the Pdgfra signal (green) with fluorescein-tyramide. Scattered individual Fgfr3⁺ and Pdgfra⁺ cells can be seen throughout both white and grey matter of the cord, but these are separate and discrete cell populations. We conclude that the great majority of Fgfr3⁺ cells in the cord are not OLPs.