Response of Retinal Ganglion Cells to Stretch Injury in the Optic Nerve of the Adult Guinea Pig

Morphology, Ophthalmology

Islam, Md. Nazrul

University:University of Glasgow

关键词: Morphology, Ophthalmology;   

Others  :  http://theses.gla.ac.uk/76374/1/13834119.pdf

来源: University of Glasgow

【 摘 要 】

An established model for axonal injury in the optic nerve of the adult guinea pig (Gennarelli et al.. 1989) has allowed analysis of the response of the ganglion cell to stretch injury. Six adult guinea pigs, two in each survival group, were killed at 3, 7 and 14 days after stretch injury. Retinas were processed for light microscopy and transmission/scanning electron microscopy. A morphometric study was carried out on the TEM micrographs. Retinas from the left eye were used as control material. Central chromatolysis occurs in about one third of the ganglion cells three days after injury. The majority of the injured ganglion cells demonstrate degenerative changes at seven days after injury. At 14 days after injury, severely degenerative and dying ganglion cells are noted. These cells have grossly mis-shapen nuclei, disappearance of cytoplasmic organelles and the occurrence of dense bodies in their cytoplasm, with focal aggregation of chromatin in the nuclei. These changes are indicative of necrobiosis of these cells. Small ganglion cells do not demonstrate any morphological changes. However, at 7 and 14 days after injury, a noble and exciting morphological change indicative of a regenerative response occurs in a few ganglion cells. These morphological changes are the assumption of an irregular nuclear profile, enlarged vacuolated nucleolus and, in addition, the occurrence of discrete Nissl bodies in the cytoplasm. These changes are comparable to those documented in regenerative neurons of the facial and hypoglossal nuclei (Jones & Lavelle, 1986; Hall & Borke, 1988) after axotomy. Proliferation of Muller cell and astrocyte processes and microglial cells is found at 7 and 14 days after stretch injury. Phagocytic activity of the microglial cells is noted. After comparative study it can be concluded that the time course of chromatolysis is longer in stretch injury than in either crush or transection of the optic nerve. That the level of injury is less severe than in the latter two models of axonal injury, and that this lesser injury allows the demonstration of an attempted regenerative response by a number of retinal ganglion cells.