[Retinopetal neurons and fibers in the lamprey]

The structure of the retinopetal system was studied in lampreys (Lampetra fluviatilis) using the HRP method. Preliminary chemical destruction of the retina or the optic nerve transsection ceased the anterograde axonal transport in the retinofugal fibres, and permitted observing the centrifugal visual projections without marking the retinofugal fibres. The cells of retinopetal system were found in the periventricular tegmental zone and in the reticular zone of mesencephalon. Retinopetal fibres followed the axial optic tract.