Secondary effects of fetal eye damage in rats on intact central optic projections.

Lesions have been made damaging the whole or part of the retina of one eye in a series of rats from fetal days 16 through 20. The projection from the unlesioned eye when tested at postnatal times fills the visual centers contralateral to the lesioned eye either completely (after total eye lesions) or partially (after subtotal retinal lesions). In no case is the density or distribution of the aberrant ipsilateral retinotectal pathway greater than after comparable lesions made at birth. The suggestion is offered that a particular population of ganglion cells contributes the aberrant ipsilateral pathway and that the stimulus for the pathway is effective close to birth and depends on damaging optic axons from one eye some time before then.