title: Ocular anatomy, ganglion cell distribution and retinal resolution of a killer whale (Orcinus orca).
abstract: Retinal topography, cell density and sizes of ganglion cells in the killer whale (Orcinus orca) were analyzed in retinal whole mounts stained with cresyl violet. A distinctive feature of the killer whale's retina is the large size of ganglion cells and low cell density compared to terrestrial mammals. The ganglion cell diameter ranged from 8 to 100 µm, with the majority of cells within a range of 20-40 µm. The topographic distribution of ganglion cells displayed two spots of high cell density located in the temporal and nasal quadrants, 20 mm from the optic disk. The high-density areas were connected by a horizontal belt-like area passing below the optic disk of the retina. Peak cell densities in these areas were evaluated. Mean peak cell densities were 334 and 288 cells/mm(2) in the temporal and nasal high-density areas, respectively. With a posterior nodal distance of 19.5 mm, these high-density data predict a retinal resolution of 9.6' (3.1 cycles/deg.) and 12.6' (2.4 cycles/deg.) in the temporal and nasal areas, respectively, in water.
authors.affiliation: Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia. alla-mass@mail.ru
authors.forename: Alla M
authors.initials: AM
authors.lastname: Mass
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Supin
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Abramov
authors.forename: Lev M
authors.initials: LM
authors.lastname: Mukhametov
authors.forename: Elena I
authors.initials: EI
authors.lastname: Rozanova
mesh_terms: D000818:Animals; D002452:Cell Count; D005123:Eye / Q000033:anatomy & histology*; D012160:Retina / Q000033:anatomy & histology / Q000166:cytology* / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000166:cytology*; D014792:Visual Acuity / Q000502:physiology; D050685:Whale, Killer / Q000033:anatomy & histology* / Q000502:physiology*