title: The distribution of photoreceptors, dopaminergic amacrine cells and ganglion cells in the retina of the North American opossum (Didelphis virginiana).
abstract: Quantitative light microscopic techniques have been applied to photoreceptors, ganglion cells and dopaminergic amacrine cells in the retina of the North American opossum Didelphis virginiana. This marsupial has a retina with a central areal specialization where ganglion cells reach a maximum density of 2900/mm2 and cone photoreceptors are concentrated. However, the retina is very much rod dominated and there is a ring of peak rod density approximately 2 mm around the area centralis (a.c.). At the a.c. the cone to rod ratio is 1:50 while in peripheral retina it is 1:120. Dopaminergic amacrines, revealed by induced fluorescence (Fa/Glu) techniques are extremely numerous in opossum retina reaching a peak density at the a.c. and distributed in a high density plateau covering much of tapetal superior retina. Opossum retina is compared to mammalian retinas, particularly cats, with the aim of understanding the evolution of mammalian retinal circuits.
mesh_terms: D000818:Animals; D002452:Cell Count; D004298:Dopamine / Q000032:analysis; D009893:Opossums / Q000033:anatomy & histology*; D009900:Optic Nerve; D010786:Photoreceptor Cells / Q000166:cytology*; D012160:Retina / Q000032:analysis / Q000166:cytology*; D012165:Retinal Ganglion Cells / Q000166:cytology*
chemical_list: D004298:Dopamine