Beltran William A, Cideciyan Artur V, Guziewicz Karina E, Iwabe Simone, Swider Malgorzata, Scott Erin M, Savina Svetlana V, Ruthel Gordon, Stefano Frank, Zhang Lingli, Zorger Richard, Sumaroka Alexander, Jacobson Samuel G, Aguirre Gustavo D
Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
PLoS One. 2014 Mar 5;9(3):e90390. doi: 10.1371/journal.pone.0090390. eCollection 2014.
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.
视网膜特化区域赋予脊椎动物以更高分辨率审视其视野相应区域的能力。在灵长类动物（包括人类）中发现的一个高度特化区域是中央凹，其特征是高密度的视锥光感受器，这些光感受器单独与中间神经元相连，并且视网膜神经节细胞（RGCs）偏移形成一个中央没有视网膜毛细血管和视网膜内层神经元的凹陷。在犬类中，在一个地形上类似的视网膜区域发现了RGC密度的局部增加，该区域被定义为中央区。虽然犬类视网膜没有中央凹，但尚未有关于中央区内光感受器的详细检查报告。通过体内和体外成像，我们识别出一个视网膜区域，其视锥光感受器密度与灵长类动物中央凹类似，但没有视网膜内层的凹陷。在罕见的人类受试者中观察到的类似解剖结构被称为扁平中央凹。此外，在人类中导致黄斑变性的两个不同基因突变的犬类，在新识别出的类似犬类中央凹的区域最早出现疾病。我们的结果挑战了这样一个教条，即在哺乳动物系统发育树中，具有中央凹的灵长类动物是视网膜具有中央视锥束的唯一谱系。此外，自然发生的视网膜变性倾向于改变这个富含视锥细胞的区域，填补了人类黄斑变性临床相关动物模型的空白。
