The freshwater butterfly fish, Pantodonbncliiiolzi, is a member of the most primitive radiation of teleosts. The retinofugal projections were studied in this fish with autoradiographic and horseradish peroxidase (MRP) methods, and the cytoarchiteclure of the relinorecipicnt regions in the diencephalon and prctcctum was analyzed with Bodian-, cresylechl-violct- and acetylcholinesterase-rcactcd sections. The rostral diencephalon of Pantodon contains a large retinorecipicnt nucleus, not previously identified in any other fish, i.e. nucleus rostrolatcralis. Other nuclei that are described correspond to those previously recognized in other species. The majority of retinorecipicnt nuclei arc positive for acetylcholinesterase, particularly those in the prctcctum, as has been found in other species of teleosts. Most of the retinofugal fibers decussate in the optic chiasm. Some fibers project via the axial optic tract to preoptic nuclei and a region in the rostral hypothalamus. Fibers leave the medial optic tract to terminate in nucleus rostrolatcralis and in dorsal and ventral thalamic nuclei, accessory optic and tubercular nuclei, periventricular and central pretectal nuclei, and sparsely in the deep teclal fascicle and terminal field. Dorsal optic tract fibers project to the dorsal accessory optic nucleus. superficial and central pretectal nuclei, and superficial and deep teclal layers. Ventral optic tract fibers project to the superficial pretectum. accessory optic nuclei, posterior tuberculum. nucleuscorticalis in the central pre-lectum. and superficial tcetal layer. Fibers that remain in the ipsilalcral optic tract project to most of the targets reached by contralateral!)- projecting fibers. A few fibers in the contralateral medial optic tract redecus-satc via the posterior commissure to reach the ipsilaleral periventricular pretectum. No labeled retinopetal cells caudal to the olfactory bulb were identified in any of the HRP cases.
All Science Journal Classification (ASJC) codes
- Behavioral Neuroscience
- Developmental Neuroscience
- Ecology, Evolution, Behavior and Systematics