Retinal projections in cyprinid fishes: a degeneration and radioautographic study.

The retinal projections of three species of cyprinid fish (Cyprinus macrolepidotus, Cyprinus carpio, Rutilus rutilus) were examined with Nauta and Fink-Heimer methods following enucleation and with radioautography following intraocular injection of [3H]-L-proline. Optic tract axons cross completely in the optic chiasma and are distributed to the hypothalamus (nucleus opticus hypothalamicus pars magnocellularis), the thalamo-pretectal region (11 distinct primary optic centers), and the tectum opticum (stratum fibrosum et griseum superficiale, stratum griseum centrale and stratum album centrale). No accessory optic tract was found. The experimental studies on visual projection of various teleosts are reviewed and discussed.