A quantitative comparison of the reactions of retinal ganglion cells to optic nerve crush in neonatal and adult mice.

The response of neurons and glia of the ganglion cell layer of the retina to optic nerve crush was studied in adult and neonatal albino mice between 10-85 days post-lesion (dpl). The numbers of ganglion cells and glia surviving optic nerve transection were quantified using Nissl-stained retinal whole mounts. Large- and intermediate-sized ganglion cells were more sensitive to axotomy in the optic nerve than small-sized cells. About 80% of the former cells degenerated by 10 dpl in adult mice whilst 90-100% were affected in neonates. 40-60% of the small-sized ganglion cells survived in adults whilst in neonates, although a similar number escaped the effects of axotomy at 10 dpl, by 30 dpl only less than 10% remained. These aspects were reflected in the changes in the relative frequency distribution with time of ganglion cells in normal and lesioned mice. No significant alterations in glial cells in the ganglion cell and fibre layers of the retina were recorded at any time of lesioning the optic nerve.