Attachment and differentiation of neural progenitors. Neural progenitors were expanded in the presence of FGF to obtain increased numbers of cells. Progenitors that remained attached to the tissue culture plate after 3 d maintained their expression of Sox1 (phase contrast in A; Sox1-GFP in B) as well as other neural progenitor markers, nestin, Pax2 and Pax6 (C) which were expressed in both the floating (FS) and proliferating progenitors (P) that were expanded in FGF as detected by RT-PCR. Math1 and Ngn1 were expressed starting at the neural progenitor stage and were present in differentiated cells (D) as well. Neurons from the spiral ganglion (SG) of a newborn mouse are shown for comparison. Low power image of neural lineage cell types formed after culture without FGF in the monolayer for 7 d is shown in D. Cells were positive for Sox1-GFP (shown in green), β-III tubulin (shown in white), and GFAP (shown in red). A high power image shown in E is positive for neural (β-III tubulin staining shown in green), glial (GFAP staining shown in red), and oligodendrocyte markers (O4 staining shown in blue). Neurons obtained after 10 d could be detected with NeuN (red) and β-III tubulin antibodies (green) in F. The neurons formed in the mixture included neurons with tyrosine hydroxylase expression (G, in red) as well as β-III tubulin (G, in green). DAPI is shown in blue.