A QUALITATIVE AND QUANTITATIVE-ANALYSIS OF THE RESPONSE OF THE RETINAL GANGLION-CELL SOMA AFTER STRETCH INJURY TO THE ADULT GUINEA-PIG OPTIC-NERVE

The development of a model for focal axonal injury in the optic nerve of the adult guinea-pig has allowed a qualitative and quantitative ana lysis of the response of the retinal ganglion cell soma to this type o f injury. Large and medium sized retinal ganglion cells show classic ' central chromatolysis' in about 30% of ganglion cells between three an d seven days after injury, a high proportion of which undergo degenera tion between seven and 14 days. Small ganglion cells and small neurons do not demonstrate any morphological response to stretch injury of th e optic nerve. However, a small number of larger ganglion cells demons trate enlargement of the cell soma and nucleolus together with reconst itution of the rough endoplasmic reticulum between seven and 14 days a fter stretch injury. We suggest that these cells are either recovering from or regenerating after a non-disruptive lesion to their axons. We suggest that some of these morphological changes parallel documented regenerative responses in peripheral/extrinsic neurons after injury to their axons. We conclude that the time course of the 'axon reaction' after stretch injury to axons is longer than that obtained after crush or transection. We provide good morphological evidence that the level of injury after application of non-disruptive mechanical strain to ax ons is less severe than in the former two models of axonal injury and that a proportion of damaged neurons do not die but rather demonstrate either/or recovery or a regenerative response.