FIGURE 1.

FA rescues proliferation and differentiation potential of neural progenitors from Sp^−/− embryos. A, neurospheres were grown from closed neural tubes of WT, open neural tubes of Sp^−/−, and open neural tubes of Sp^−/− with 200 μg/ml of FA (E 10.5) in 4 ml of media containing EGF and bFGF. To initiate the colonies 5 × 10⁴ cells/ml were used. A group of cells was considered to be a neurosphere at 50 μm or larger. Neurospheres were counted on day 7. B, each data point represents one (independently prepared) culture and each culture was derived from one embryonic caudal neural tube. In the absence of FA, colony forming units were significantly lower from Sp^−/− embryos (*, p < 0.05) compared with WT. FA significantly increased the number of neurospheres in Sp^−/− but not the WT (**, p < 0.01) sphere culture. C, EdU incorporation into the neurospheres indicates that FA treatment reversed the reduced number of neurospheres from Sp^−/− mutants to near WT levels via cell proliferation. Experiments were performed in triplicate with each data point in duplicate.