title: Canine retina has a primate fovea-like bouquet of cone photoreceptors which is affected by inherited macular degenerations.
abstract: Retinal areas of specialization confer vertebrates with the ability to scrutinize corresponding regions of their visual field with greater resolution. A highly specialized area found in haplorhine primates (including humans) is the fovea centralis which is defined by a high density of cone photoreceptors connected individually to interneurons, and retinal ganglion cells (RGCs) that are offset to form a pit lacking retinal capillaries and inner retinal neurons at its center. In dogs, a local increase in RGC density is found in a topographically comparable retinal area defined as the area centralis. While the canine retina is devoid of a foveal pit, no detailed examination of the photoreceptors within the area centralis has been reported. Using both in vivo and ex vivo imaging, we identified a retinal region with a primate fovea-like cone photoreceptor density but without the excavation of the inner retina. Similar anatomical structure observed in rare human subjects has been named fovea-plana. In addition, dogs with mutations in two different genes, that cause macular degeneration in humans, developed earliest disease at the newly-identified canine fovea-like area. Our results challenge the dogma that within the phylogenetic tree of mammals, haplorhine primates with a fovea are the sole lineage in which the retina has a central bouquet of cones. Furthermore, a predilection for naturally-occurring retinal degenerations to alter this cone-enriched area fills the void for a clinically-relevant animal model of human macular degenerations.
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: William A
authors.initials: WA
authors.lastname: Beltran
authors.affiliation: Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Artur V
authors.initials: AV
authors.lastname: Cideciyan
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Karina E
authors.initials: KE
authors.lastname: Guziewicz
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Simone
authors.initials: S
authors.lastname: Iwabe
authors.affiliation: Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Swider
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Scott
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Savina
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Gordon
authors.initials: G
authors.lastname: Ruthel
authors.affiliation: Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Frank
authors.initials: F
authors.lastname: Stefano
authors.affiliation: Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Lingli
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Richard
authors.initials: R
authors.lastname: Zorger
authors.affiliation: Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Alexander
authors.initials: A
authors.lastname: Sumaroka
authors.affiliation: Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Jacobson
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Gustavo D
authors.initials: GD
authors.lastname: Aguirre
mesh_terms: D000818:Animals; D018118:Chloride Channels / Q000235:genetics; D004283:Dog Diseases / Q000235:genetics / Q000473:pathology*; D004285:Dogs; D005136:Eye Proteins / Q000235:genetics; D005584:Fovea Centralis / Q000473:pathology*; D008268:Macular Degeneration / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D009154:Mutation; D012160:Retina / Q000473:pathology; D017949:Retinal Cone Photoreceptor Cells / Q000473:pathology*
chemical_list: D018118:Chloride Channels; D005136:Eye Proteins