Fig. 4. Foetal and postnatal NLBs contain bipotential progenitors of enteric neurons and glia. (A-C,G-I) Typical colonies generated from single GFP+ cells isolated from foetal (A-C) and postnatal (G-I) NLBs on day 1 (A,G), day 5 (B,H) and day 10 (C,I). (D-F,J-L) Equivalent colonies immunostained with TO-PRO-3 (blue; to reveal the cell nucleus), TuJ1 (red; to identify neurons) and GFAP (green; to identify glia). The cell shown in D and J (day 1) had weak GFP signal but lacked the characteristic TuJ1 and GFAP staining. To avoid confusion with the GFP-specific signal, E and K (day 5) and F and L (day 10) show sectors of colonies in which the retroviral transgene had been extinguished. TuJ1+ cells were detected in day 5 and day 10 colonies but GFAP+ cells were detected only in day 10 colonies. Arrows in F and L point to two neighbouring cells that express TuJ1 or GFAP. (M) Cells in foetal colonies have higher proliferative capacity. Five-dayold colonies from foetal and postnatal EPCs were stained with the mitotic marker H3p. The fraction of H3p+ cells in foetal colonies was higher relative to that of postnatal colonies.