The cells of origin of the aberrant recrossed retinotectal projection in the rat.

The cells of origin of the aberrant recrossed retinotectal projection induced by neonatal unilateral eye enucleation and collicular lesion in rats were studied using horseradish peroxidase and fluorescent dyes as pathway tracers. The results showed that labelled ganglion cells which gave rise to the recrossed retinotectal projection were distributed in almost the entire area of the remaining retina. However, more labelled cells were observed in the nasal than in the temporal half of the retina, and very few cells contributing to the recrossed projection were located in the lower temporal retinal crescent where cells of the uncrossed retinotectal fibers were heavily concentrated. In addition, a small number of recrossed retinotectal fibers were found to arise from ganglion cells which simultaneously sent out uncrossed retinotectal fibers terminating in the same remaining colliculus.