The cone photoreceptor mosaic of the green sunfish,Lepomis cyanellus

Abstract

Recent empirical and theoretical evidence has implicated the geometrical birefringence of the double cones of the green sunfish (Lepomis cyanellus) as the biophysical basis of this vertebrate's sensitivity to polarized light. Because of the intimate link between the organization of the cone-photoreceptor mosaic and the psychophysical details of polarization sensitivity, we have examined the structural features of the green sunfish cone-photoreceptor mosaic, in particular the orientation of the elliptical cross sections of the double cones. Our primary observations are that (1) the arrangement of the cone-photoreceptor mosaic is constant across the retina (with two regional exceptions), with double cones arranged in a rhombic mosaic and aligned roughly ±45 deg to the nearest retinal margin; (2) the double-cone/single-cone ratio is everywhere the same; (3) cone density is inhomogeneous across the retina, with the highest densities in the temporal hemiretina. These results are discussed as they relate to the animal's retinal growth and visual mechanisms, particularly the sensitivity to polarized light.

Cone photoreceptor regeneration in adult fish retina: phenotypic determination and mosaic pattern formation

“…Animal husbandry, anesthesia, and euthanasia techniques were as described previously (Cameron and Easter, 1993). Fully light adapted fish were used in all procedures.…”

“…The resulting eye cups were fixed by immersion in 4% paraformaldehyde in 0.05 M PO, buffer overnight. One or more small pellets of the fluorescent carbocyanine dye DiI (l,l'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate;Molecular Probes, Eugene, OR;Honig and Hume, 1986;Godement et al, 1987) were embedded within the cut face of the optic nerve (n = 13), and the eye cups were incubated in fixative at 45°C for 5 d. DiI was incoruorated into retinal aanelion cell (RGC) axonal membranes local to the pellet, and retrogGde?y labeled annuli of RGC somata and dendrites (Easter, 1992;Cameron and Easter, 1993), and one of these annuli generally intersected the lesion site or lay peripheral to it. Retinal whole-mounts were made with the pigment epithelium side down, cover slipped with 50% glycerol, 50% PO, buffer, and viewed with epifluorescence microscopy.…”

“…In normal temporal retina, RGC axons converge directly from their somata toward the optic papilla, the labeled annuli are contiguous and circular, and the DCs are arranged in "spokes" that extend in the centroperipheral direction parallel to the RGC axons (Cameron and Easter, 1993). In the retinas with a patch removed, the axons and the spokes were locally deflected toward the center of the lesion.…”

Behavioural investigation of polarisation sensitivity in the Japanese quail (Coturnix coturnix japonica) and the European starling(Sturnus vulgaris)

“…In other vertebrates, a regular 'mosaic' pattern of cone photoreceptors in the retina is believed to be a requirement for polarisation sensitivity (Cameron and Easter, 1993;NovalesFlamarique and Hawryshyn, 1998a;Hawryshyn, 2000). It has been proposed that the tilt of the partition between the two members of the double cone may lead to e-vector selective reflection onto adjacent UV-sensitive cones and hence may provide a possible mechanism for polarisation detection (Novales-Flamarique et al, 1998;Hawryshyn, 2000).…”

Control of Cellular Pattern Formation in the Vertebrate Inner Retina by Homotypic Regulation of Cell-Fate Decisions

“…Note the overall similarity between the in vivo and model-derived patterns (see Results) (Tables 1, 2). Shafer, 1900;Lyall, 1957;Engström, 1963;Marc and Sperling, 1976;Williams, 1988;Wikler and Rakic, 1990;Wässle and Boycott, 1991;Cameron and Easter, 1993;Vaney, 1994;Cook, 1996;Cameron andCarney, 2000, 2004;Cook and Chalupa, 2000;Galli-Resta, 2000;Rockhill et al, 2000;Stenkamp et al, 2001).…”