The Best-Vision Zones and Visual Resolution of the Retina of Neonatal Bottlenose Dolphins Tursiops truncatus

The topography of ganglion cells in the retina of three neonatal bottlenose dolphins Tursiops truncatus has been studied in retinal wholemounts. Two areas of high ganglion cell density have been identified in the form of local spots in the temporal and nasal quadrants of the retina, near a horizontal diameter at a distance of 10-15 mm from the optical disk. The maximum density of ganglion cells in these areas on average for five preparations is 657 and 636 cells/mm² in the temporal and nasal quadrants, respectively. The retinal resolution, estimated by the maximum density of ganglion cells and a posterior nodal distance of 13 mm, was 0.17° for the temporal quadrant and 0.18° for the nasal one. These data are comparable with the results for the previously studied adult dolphin and whale species.