Centrifugal Visual System of Rat

The sensory organs transmit the stimuli of the§outside world towards the central nervous system.§Pathways exist in the opposite direction: from the§central nervous system towards the sensory organs§(centrifugal or retinopetal fibers). In bird and§lower vertebrates the origin of the retinopetal§fibers is well described now, but in mammals data on§the existence and the origin of the retinopetal§fibers are contradictory. §In our present work we have provided direct evidence§for a novel retinopetal pathway in rat between the§limbic structures and the retina. We call this§distinct pathway as limboretinal one. Intravitreous§injection of retrograde tracer labeled cells in§several limbic structures: the hippocampus, dentate§gyrus, the indusium griseum, the olfactory tubercle,§and the medial habenula, and in hypothalamic§magnocellular nuclei. Their number was 1495±516. Some§of the retrograde labeled cells were also labeled§with VIP, PACAP or LHRH. Iontophoretic application of§an anterograde tracer into the hippocampal formation§resulted in labeled fibers in the optic nerve and in§the retina. §We suggest to use this book to all researchers who§deal with the visual system of vertebrates.