Mapeamento das projeções retinianas para o sistema óptico acessório, colículo superior e complexo pré-tectal do sagui (callithrix jacchus)

The accessory optical system, the pretectal complex, and superior colliculus are important control centers in a variety of eye movement, being extremely necessary for image formation, consequently to visual perception. The accessory optical system is constituted by the nuclei: dorsal terminal nucleus, lateral terminal nucleus, medial terminal nucleus and interstitial nucleus of the posterior superior fasciculus. From a functional point of view they contribute to the image stabilization, participating in the visuomotor activity where all system cells respond to slow eye movements and visual stimuli, which is important for the proper functioning of other visual systems. The pretectal complex comprises a group of nuclei situated in mesodiencephalic transition, they are: anterior pretectal nucleus, posterior pretectal nucleus, medial pretectal nucleus, olivary pretectal nucleus and the nucleus of the optic tract, all retinal projection recipients and functionally are related to the route of the pupillary light reflex and the optokinetic nystagmus. The superior colliculus is an important subcortical visual station formed by layers and has an important functional role in the control of eye movements and head in response to multisensory stimuli. Our aim was to make a mapping of retinal projections that focus on accessory optical system, the nuclei of pretectal complex and the superior colliculus, searching mainly for pretectal complex, better delineation of these structures through the anterograde tracing with the B subunit of cholera toxin (CTb) followed by immunohistochemistry and characterized (measured diameter) synaptic buttons present on the fibers / terminals of the nucleus complex pré-tectal. In our results accessory optical system, including a region which appears to be medial terminal nucleus and superior colliculus, were strongly marked by fibers / terminals immunoreactive CTb as well as pretectal complex in the nucleus: optic tract, olivary pretectal nucleus, anterior pretectal nucleus and posterior pretectal nucleus. According to the characterization of the buttons it was possible to make a better definition of these nucleus.

Centros subcorticais dos sistemas visual primário e óptico acessório no mocó (kerodon rupestris): caracterização pela projeção retiniana e citoarquitetura.

The primary and accessory optic systems comprise two set of retinorecipient neural clusters. In this study, these visual related centers in the rock cavy were evaluated by using the retinal innervations pattern and Nissl staining cytoarchigtecture. After unilateral intraocular injection of cholera toxin B subunit and immunohistochemical reaction of coronal and sagittal sections from the diencephalon and midbrain region of rock cavy. Three subcortical centres of primary visual system were identified, superior colliculus, lateral geniculate complex and pretectal complex. The lateral geniculate complex is formed by a series of nuclei receiving direct visual information from the retina, dorsal lateral geniculate nucleus, intergeniculate leaflet and ventral lateral geniculate nucleus. The pretectal complex is formed by series of pretectal nuclei, medial pretectal nucleus, olivary pretectal nucleus, posterior pretectal nucleus, nucleus of the optic tract and anterior pretectal nucleus. In the accessory optic system, retinal terminals were observed in the dorsal terminal, lateral terminal and medial terminal nuclei as well as in the interstitial nucleus of the superior fasciculus, posterior fibres. All retinorecipient nuclei received bilateral input, with a contralateral predominance. This is the first study of this nature in the rock cavy and the results are compared with the data obtained for other species. The investigation represents a contribution to the knowledge regarding the organization of visual optic systems in relation to the biology of species.