Electron microscopy. CD133⁺ cells at the start of culture (A-B) and on culture with (C,E,G) and without TGF-β (D,F,H) for 7 days (C-D), 14 days (E-F), and 18 days (G-H). (E) Bottom left corner: cell shows signs of apoptosis. Bars represent 5 μm. Comments on the cell structure at the various time points are detailed in the text. Images were taken with analySIS 5.0 software through a MegaView III camera applied to a JEM 1010 electron microscope at 80kV (Jeol), and were processed for print with Photoshop 6.0 for Macintosh (Adobe).