Retinal Ganglion Cell Distribution and Spatial Resolving Power in Deep-Sea Lanternfishes (Myctophidae)

Abstract

Topographic analyses of retinal ganglion cell density are very useful in providing information about the visual ecology of a species by identifying areas of acute vision within the visual field (i.e. areas of high cell density). In this study, we investigated the neural cell distribution in the ganglion cell layer of a range of lanternfish species belonging to 10 genera. Analyses were performed on wholemounted retinas using stereology. Topographic maps were constructed of the distribution of all neurons and both ganglion and amacrine cell populations in 5 different species from Nissl-stained retinas using cytological criteria. Amacrine cell distribution was also examined immunohistochemically in 2 of the 5 species using anti-parvalbumin antibody. The distributions of both the total neuron and the amacrine cell populations were aligned in all of the species examined, showing a general increase in cell density toward the retinal periphery. However, when the ganglion cell population was topographically isolated from the amacrine cell population, which comprised up to 80% of the total neurons within the ganglion cell layer, a different distribution was revealed. Topographic maps of the true ganglion cell distribution in 18 species of lanternfishes revealed well-defined specializations in different regions of the retina. Different species possessed distinct areas of high ganglion cell density with respect to both peak density and the location and/or shape of the specialized acute zone (i.e. elongated areae ventro-temporales, areae temporales and large areae centrales). The spatial resolving power was calculated to be relatively low (varying from 1.6 to 4.4 cycles per degree), indicating that myctophids may constitute one of the less visually acute groups of deep-sea teleosts. The diversity in retinal specializations and spatial resolving power within the family is assessed in terms of possible ecological functions and evolutionary history.

Retinal specialization through spatially varying cell densities and opsin coexpression in cichlid fish

“…Following the protocols described in de Busserolles et al (2014aBusserolles et al ( , 2014b, topographic distribution of single cones, double cones, total cones and ganglion cells were assessed using the optical fractionator technique (West, 1991) modified by Coimbra et al (2009Coimbra et al ( , 2012 for use in retinal whole mounts. Briefly, for each whole mount, the outline of the retina was digitized using a ×5 objective (numerical aperture 0.16) mounted on a compound microscope (Zeiss Imager.Z2) equipped with a motorized stage (MAC 6000 System, Microbrightfield, USA), a digital colour camera (Microbrightfield) and a computer running StereoInvestigator software (Microbrightfield).…”

Microhabitat partitioning correlates with opsin gene expression in coral reef cardinalfishes (Apogonidae)

“…Few individuals were investigated in this study due to the challenge in processing such small eyes using this method. However, previous studies (de Busserolles, Fitzpatrick, Marshall, & Collin, ; de Busserolles, Marshall, & Collin, ) have shown a low intraspecific variability in retinal topography in fishes, and the analysis of two individuals of Ostorhinchus doederleini (Figure S2) suggests low intraspecific variability in cardinalfishes also. Using the stereological software StereoInvestigator (Microbrightfield), topographic distribution of photoreceptors and ganglion cells was assessed using the optical fractionator technique designed by West, Slomianka, and Gundersen () and modified by Coimbra, Nolan, Collin, and Hart ().…”

Retinal ganglion cell topography and spatial resolving power in the white rhinoceros (Ceratotherium simum)

“…The harvesting of tissue from this specimen was approved by the University of the Witwatersrand Animal Ethics Committee (clearance number 2008/36/1). Because other studies in many vertebrates have shown that interindividual variation in the total number and topographic distribution of retinal ganglion cells is generally low (Coimbra et al, 2013(Coimbra et al, , 2014a(Coimbra et al, , 2014bLisney et al 2012Lisney et al , 2013aLisney et al , 2013bde Busserolles et al, 2014), and given the endangered status of the white rhinoceros, the eyes from this single specimen were considered representative for the characterization of the retinal topographic specializations in this species.…”