Fig. 2. e-ATP normally induces cell death in the developing population of cholinergic neurons. (A,B) Total number of cholinergic (ChAT) cells in the GCL (A) and the INL (B) 24 hours after in vivo treatment with apyrase (filled squares), suramine (filled triangles), or oATP (filled circles); control non-injected (open circles); vehicle-injected (open squares). The abscissa gives the age of analysis. The cholinergic cell number is increased if the treatment is administered between P1 and P3, but not on P5. Between 4 and 8 retinas were analyzed for each treatment and age point. (C) New cell genesis does not contribute to the increased number of cholinergic neurons, since BrdU (red) administered after the treatment does not label any cholinergic cells, identified here with an antibody to Islet-1/2 (green), which also labels retinal ganglion cells (Galli-Resta et al., 1997). Confocal image of a P2 retinal section. (D) Cellular debris immunoreactive for choline acetyltransferase can be observed in P2 whole-mount retinas 90 minutes after a shot of 5 mM ATP in the eye (left and central panel), while they are very rarely seen in normal P2 retinas (right panel). Scale bar: 50 µm in C; 20 µm in D.