Retinofugal and retinopetal projections in the cichlid fish XXXX .

@entity376 @entity2083 @entity9215
The retinofugal and retinopetal projections of the cichlid fish @entity9215 were studied by applying cobaltous- @entity376 to the optic nerve. Retinal axons terminate bilaterally in a preoptic-suprachiasmatic region between the base of the third ventricle and the anterior genu of the horizontal commissure and among periventricular cells along the sides of the ventricle. Other retinal axons innervate the tuberal region of the hypothalamus anterior to the infundibulum. Targets innervated in the pretectum include nucleus lateralis geniculatus and dorsal, medial, and ventral pretectal nuclei. Three other targets (nucleus opticus dorsolateralis, nucleus opticus commissurae posterior, nucleus opticus ventrolateralis) are innervated by fibers that leave the medial edge of the dorsal optic tract. Two other targets (basal optic nucleus and accessory optic nucleus) are innervated by fibers from the ventral optic tract. These retinal projections are similar to those previously reported for @entity2083 in an experiment that used the cobaltous- @entity376 method (Springer and Gaffney, J. Comp. Neurol. 203:401-424, '81). Retinotectal optic axons were found in a superficial lamina just above the stratum opticum, in the stratum opticum, in three layers of the stratum fibrosum et griseum superficiale, in a lamina just beneath the stratum fibrosum et griseum superficiale, and in the stratum album centrale just above the stratum periventriculare. This result is similar to that previously reported for @entity2083 ; however, the spatial relationships between the various retinorecipient laminae differ for @entity2083 and @entity9215 . Efferents to the retina originate in two nuclei and both project contralaterally. The first is the nucleus olfactoretinalis, which is located ventrally between the olfactory lobe and telencephalon. It consists of about 400 cells, of which, approximately 200 cells project to the retina. The second retinopetal nucleus, nucleus thalamoretinalis, is a diffuse group of about 200 cells that project to the retina.
