A retinopetal nucleus in the preoptic area in a teleost, Navodon modestus.

Following horseradish peroxidase (HRP) applications to the optic nerve of a teleost (Navodon modestus), a retinopetal nucleus was identified in the contralateral preoptic area. The nucleus was composed of small (7-10 microns) round cells. Centrifugal fibers from the nucleus were traced to the inner nuclear layer of the ipsilateral retina by both orthograde HRP and Fink-Heimer methods. The cells in the nucleus showed no neurosecretion. The retinopetal nucleus or neurons could not be found in Carassius carassius. No retinopetal neurons were found in the optic tectum in both species.