Morphology and density distribution of cone photoreceptor in the retina of the atlantic stingray, Dasyatis sabina

Light miscroscopy of the retina in the Atlantic stingray, Dasyatis sabina , reveal two distinct photoreceptor types. Histological criteria establish the two cell types as morphological rods and cones. The retina was studied through a sequential series of vertical sections in a protocol designed to evaluate the entire retina. By performing differential counts in multiple regions and expressing cones as a percent of the total photoreceptors in a domain, it was possible to determine relative cone density and distribution. Cone distribution varies throughout the retina in two patterns. First, relative cone density gradually decreases peripherally. Second, a cone‐rich band occurs along the horizontal axis of the eye, extending from ora serrata to ora serrata. This structure appears to be a visual streak. Both distribution patterns are statistically significant and are consistent among animals regardless of age. © 1994 Wiley‐Liss, Inc.