Retinal projections in the short‐tailed fruit bat, Carollia perspicillata, as studied using the axonal transport of cholera toxin B subunit: Comparison with mouse

Abstract

To provide a modern description of the Chiropteran visual system, the subcortical retinal projections were studied in the short-tailed fruit bat, Carollia perspicillata, using the anterograde transport of eye-injected cholera toxin B subunit, supplemented by the silver-impregnation of anterograde degeneration following eye removal, and compared with the retinal projections of the mouse. The retinal projections were heavily labeled by the transported toxin in both species. Almost all components of the murine retinal projection are present in Carollia in varying degrees of prominence and laterality. The projections: to the superior colliculus, accessory optic nuclei, and nucleus of the optic tract are predominantly or exclusively contralateral; to the dorsal lateral geniculate nucleus and posterior pretectal nucleus are predominantly contralateral; to the ventral lateral geniculate nucleus, intergeniculate leaflet, and olivary pretectal nucleus have a substantial ipsilateral component; and to the suprachiasmatic nucleus are symmetrically bilateral. The retinal projection in Carollia is surprisingly reduced at the anterior end of the dorsal lateral geniculate and superior colliculus, suggestive of a paucity of the relevant ganglion cells in the ventrotemporal retina. In the superior colliculus, in which the superficial gray layer is very thin, the projection is patchy in places where the layer is locally absent. Except for a posteriorly located lateral terminal nucleus, the other accessory optic nuclei are diminutive in Carollia, as is the nucleus of the optic tract. In both species the cholera toxin labeled sparse groups of apparently terminating axons in numerous regions not listed above. A question of their significance is discussed.

The Suprachiasmatic Nucleus and the Intergeniculate Leaflet of the Flat-Faced Fruit-Eating Bat (Artibeus planirostris): Retinal Projections and Neurochemical Anatomy

“…The IGL of the flat-faced fruit-eating bat receives a bilateral retinal projection and the OD analysis indicates possible symmetrical innervation. This configuration was visualized in the short-tailed fruit bat ( Scalia et al, 2015 ) (Supplementary Table S2 ). Differently from present work, a predominantly contralateral projection was described in Nile grass rat ( Negroni et al, 2003 ), degu ( Goel et al, 1999 ), and California ground squirrel ( Major et al, 2003 ).…”

“…Nocturnal species developed perceptive senses of smell and hearing and concentrate their activity in the dark phase of the cycle ( Sousa and Menezes, 2006 ). Some animals, such as bats, have developed additional specializations (echolocation and flying), which allow them to exploit the environment and forage for food ( Simmons, 1989 ; Scalia et al, 2015 ). Chiropterans are exclusively or almost exclusively nocturnal ( Rydell and Speakman, 1995 ), and their daily patterns of activity and behavior are influenced principally by components of the light/dark cycle, such as dusk, dawn ( Erket, 1982 ), light intensity ( Haeussler and Erkert, 1978 ), moonlight ( Apple et al, 2017 ) and night length ( Frafjord, 2013 ).…”

Did you choose appropriate tracer for retrograde tracing of retinal ganglion cells? The differences between cholera toxin subunit B and Fluorogold

“…The morphologic results demonstrated that CTB displayed RGC neurites, including axons, more clearly than FG, although the specific reason for this remains unclear. We conjecture that it is due to the tracers’ individual natures; indeed, CTB is suitable for use both as a retrograde and an anterograde tracer [ 28 , 35 , 36 ], whereas FG can only be utilized as a retrograde tracer [ 27 ]. This means that CTB may be transported from cell bodies to cell processes and thereby stain neurites more clearly.…”

“…Subsequently, CTB is selectively taken up into the cytoplasm by adsorptive endocytosis [ 35 ]. In fact, CTB can also be used as an anterograde tracer [ 28 , 35 , 36 ], whereas FG can only be utilized as a retrograde tracer [ 27 ]. FG was first utilized as a retrograde fluorescent tracer by Schmued and Fallon [ 37 ].…”

Binocular vision, the optic chiasm, and their associations with vertebrate motor behavior

“…Microchiroptera have no (Pettigrew, 1986b) or very few IRP (Scalia et al, 2015). Fruit bats, Megachiroptera, which commonly use claws on the wing to climb trees and manipulate fruit (Zhang et al, 2010), possess a primate-like visual system with a large proportion of IRP and an extensively developed primary visual area (Pettigrew, 1986b;Rosa et al, 1993).…”