The topography of cone photoreceptors in the retina of a diurnal rodent, the agouti (Dasyprocta aguti).
The presence, density distribution, and mosaic regularity of cone types were studied in the retina of the diurnal agouti, Dasyprocta aguti. Longwave-sensitive (L-) and shortwave-sensitive (S-) cones were detected by antibodies against the respective cone opsins. L- and S-cones were found to represent around 90 and 10% of the cone population, respectively. There was no evidence for L- and S-opsin coexpression in agouti cones. L-cone densities were highest, up to 14,000/mm2, along a horizontal visual streak located about 2-3 mm dorsal to the optic nerve, and the L-cone distribution showed a dorsoventral asymmetry with higher densities in ventral (about 10,000/mm2) than in dorsal (about 4000/mm2) retinal regions. This L-cone topography parallels the agouti's ganglion cell topography. S-cones had a peak density of 1500-2000/mm2 in the central retinal region but did not form a visual streak. Their distribution also showed a dorsoventral asymmetry with densities around 600/mm2 in dorsal and around 1000/mm2 in ventral retinal regions. The patterning of cone arrays was assessed by the density recovery profile analysis. At all eccentricities evaluated, the S-cone mosaic less efficiently packed than the L-cone mosaic. Rod densities ranged from 47,000/mm2 in peripheral to 64,000/mm2 in central retina, and rod:cone ratios were 4:1-9:1. The comparatively low rod density and high cone proportion appear well adapted to the diurnal lifestyle of the agouti.
Rocha
Fernando Allan de Farias
FA
Departamento de Fisiologia, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil. rochaf@ufpa.br
Ahnelt
Peter K
PK
Peichl
Leo
L
Saito
Cézar A
CA
Silveira
Luiz Carlos L
LC
De Lima
Silene Maria A
SM
D000818:Animals; D002452:Cell Count; D055253:Color Vision; D055358:Cone Opsins / Q000096:biosynthesis / Q000648:ultrastructure; D007150:Immunohistochemistry; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology* / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000166:cytology; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000378:metabolism; D017299:Rod Opsins / Q000096:biosynthesis / Q000648:ultrastructure; D012377:Rodentia
D055358:Cone Opsins; D017299:Rod Opsins