DESCENDING OPTIC-NERVE DEGENERATION IN PRIMATES

Abstract

The optic nerve was severed at the orbital apex in squirrel monkeys [Saimiri sciureus] to study the descending degeneration of optic nerve axons and their ganglion cell bodies. Progressive disintegration of the axon from the site of injury back to the cell body was not detected. Instead, the entire length of individual axons seemed to degenerate simultaneously as early as 3 wk and as late as 6 wk after injury, as judged both by ultrastructural integrity and by continued slow axonal transport, a reflection of local physiologic function. The time of degeneration could not be related to the distance of the injury from the cell body. Evidently there is a signal of injury to the cell body after axotomy, though the nature of the signal and the mechanism by which it leads to cell death are unknown.