Fig. 1. Immunomicrograph showing the CNS potential of E14 rat dorsal spinal cord-derived clones. (A) A single clone can generate ß-tubulin⁺ neurones, O4⁺ oligodendrocytes and GFAP⁺ astrocytes. (B) Hedgehog signalling is not necessary for the generation of oligodendrocytes from FGF2-treated E14 rat dorsal cultures. Addition of cyclopamine or KAAD during the 7 day exposure to FGF2 does not significantly reduce numbers of oligodendrocytes generated upon mitogen withdrawal, plating and subsequent differentiation for a further 7 days (P>0.05). (C) Immunofluorescent micrograph showing representative labelling of differentiating cultures for O4-, GC- and MBP-positive cells from E14 dorsal-derived cultures following treatment with FGF2 in the presence of cyclopamine (1 µM).