Pyknosis in the RGC layer. Pyknosis in the RGC layer. A, Time course of the appearance of pyknotic cells in the ganglion cell layer of wild-type (black triangles) and bcl-2 transgenic mice (open circles) after transection of the optic nerve.B, Time course of the reduction in the number of living cells in the ganglion cell layer of wild-type (black triangles) and bcl-2 transgenic mice (open circles) after the transection of the optic nerve. Lidia Bonfanti et al. J. Neurosci. 1996;16:4186-4194 ©1996 by Society for Neuroscience