Neurogenic ability of non-pigmented CE and Müller stem cells cultured under differentiating conditions for 7 days (A) (i) Morphology of CE and Müller cells cultured under normal culture conditions in the presence of 10% serum. Non-pigmented CE cells were maintained with EGF. (ii) Under adherent conditions in the presence of ECM gel and FGF2, non-pigmented CE cells maintained their epithelial cell morphology, however, a few flattened cells were visible. In contrast, Müller stem cells acquired a neural-like morphology (white arrows). (iii) In the presence of DAPT and FGF2, CE cells ceased to proliferate and did not adopt a neural morphology. However under these conditions a greater proportion of Müller stem cells adopted a neural-like morphology. (Scale bar represents 100 μm.) (B) Western blotting of cell lysates revealed that CE cell preparations cultured under differentiating conditions (CE 6165, CE 6213 and CE 6334) did not express BRN3B, a transcription factor present in post-mitotic retinal ganglion cell precursors. However, increased expression of this protein was observed in Müller stem cells (MIO-M2, MIO-M5 and MIO-M7) cultured under similar conditions. (C) Examination of mRNA for photoreceptor gene expression revealed that in the presence of FGF2 non-pigmented CE cells and Müller stem cells expressed NRL and Rhodopsin, but that only Müller cells expressed S-Opsin. (CE = Ciliary Epithelium, FGF2 = Fibroblast Growth Factor 2.)