Purchase this article with an account.
L.C. L. Silveira, C.A. Saito, E.S. Yamada, S.M. A. deLima; Regularity and Spatial Independence Between A–Type Topic and Displaced Horizontal Cells in the Capybara Retina . Invest. Ophthalmol. Vis. Sci. 2006;47(13):157.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Capybara (Hydrochoerus hydrochaeris), the largest living diurnal rodent, has a retina bearing a visual streak and showing the highest density of A–type displaced horizontal cells among mammals so far studied (Silveira et al., 1989). We applied spatial statistics methods to study the spatial relationship between A–type topic and displaced horizontal cells in capybara's retina.
Horizontal cells were stained using the Gros–Schultze method applied to whole–mounts retinas. Three fields – dorsal (n=48), central (n=113), and ventral (n=54) – were taken to study A–type topic horizontal cells. A dorsal field containing topic (n=54) and displaced (n=23) A–type horizontal cells was also studied. We computed the regularity index (RI) by nearest neighbour distance analysis, the packing factor (PF) by density recovery profile. We also applied monovariate and bivariate Ripley's K function to evaluate horizontal cell mosaic spatial statistics.
All the mosaics formed by A–type horizontal cells were spatially regular. Monovariate Ripley's K function showed that they are statistically different from random mosaics with same densities (P<0.05); the dorsal mosaic was more regular than the others. When the displaced cells were inserted, the resultant mosaic became less regular: RI decreased from 4.4 to 3.1; PF decreased from 0.47 to 0.25. The bivariate Ripley's K function suggested that both mosaics were not correlated (P>0.05).
Like others vertebrates, capybara's A–type horizontal cells show a regular spatial pattern of distribution, which decreased if displaced horizontal cells are inserted. We interpret these results as an indicative that topic and displaced horizontal cells are two spatially independent populations.
This PDF is available to Subscribers Only