Figure 7.

Cooperation between sonic hedgehog and FGF receptor signaling is required for the generation of ventrally derived OL progenitor population in vitro. Dissociated cell cultures initiated from whole forebrains of E12.5 wild-type mice (A–C) or from the ventral portion of the forebrain from E11.5 wild-type mice (D) were grown in defined media in the presence or absence of a chemical inhibitor of Fgfrs [PD173074; 150 nm (A–C), 100 nm (D), or 300 nm (B)], inhibitor of all hedgehogs (cyclopamine; 1 μm), or both. OLP development was analyzed by immunolabeling with specific marker of early OLPs (PDGFRa) at 6 DIV (A–C) or 9 DIV (D), late OLPs (O4) at 9 DIV (A, B) double labeled with the nuclear marker Hoechst (blue). The total numbers of PDGFRa- or O4-positive cells were counted and expressed as a percentage of control. Error bars represent SEM (N = 3). Each experiment was performed at least two to three times. Scale bars, 50 μm. Note that OLP generation is strongly inhibited by either of the inhibitors.