Cone mosaics in a teleost retina: Changes during light and dark adaptation

Abstract

The square mosaic pattern of retinal cones in the guppy, Poecilia reticulata, changes during dark adaptation into a row mosaic. The functional significance of this change is discussed.

A Histological Study on the Visual Cell Layer of the Endemic Korean SpeciesLiobagrus mediadiposalis(Pisces: Amblycipitidae)

“…The cone cells are seen an irregular and random mosaic pattern, and the rod cells are also randomly situated at between cone cells. By this study, such visual cells support strongly the ecological traits of a nocturnal and bottom-dwelling freshwater fish and the vision is more dependent on the rod cell than the cone cell being smaller (Fernald, 1982;Kunz, 1980;Nag & Bhattacharjee, 1993. In addition to the eye, long and well-developed hairs on the jaw may play a role in distinguishing between the food items and the objects in the night.…”

Morphological characteristics of visual cells in the endemic Korean loach Kichulchoia multifasciata (Pisces; Cobitidae) by microscopy

“…This study shows a wide range of dispersion for the melanin pigment granules, which it is extended from RPE body to the outer segments of photoreceptor cells. In many teleosts, the visual cells of the retina show a mosaic pattern, with cones being the dominating element with rods randomly interspersed [2,20]. Typically, the cone pattern is an arrangement of four equal, double cones surrounding a single cone [10,23].…”

“…In the square pattern, the double cones have an alternating, perpendicular orientation, either having an angle of 60° or 90°. In the triangular pattern, the double cones are oriented at angles of 60° and 120° [11,12,20,23]. Some investigators have suggested that the double cones are primarily sensitive to medium and long wavelengths, whereas single cones are primarily sensitive to the shorter blue wavelengths [4,24].…”

“…Some investigators have suggested that the double cones are primarily sensitive to medium and long wavelengths, whereas single cones are primarily sensitive to the shorter blue wavelengths [4,24]. Regarding the mosaic pattern, it is known that the row pattern of double cones is especially suitable for vision in dark homochromatic environments, and the square pattern has a high adaptive capacity to varying spectral distributions in luminous environments [20,23]. These patterns occasionally show differences in some species [5,11,13,22,25,30].…”

“…This loach is a diurnal-bottom dweller that inhabits shallow streams, mostly below 30 cm depth, with having moderately rapid currents and clear water, and mainly feed on algae rather than on aquatic insects [18]. In regard to the mosaic pattern, Kunz [20] suggests it is important for detection in luminous environments. However, Rossetto et al [31] found that there is no apparent relationship between the double cone arrangement and environmental luminosity and claim instead that this pattern is well adapted to the hunting activity of predatory fish.…”