Eye of the harbour seal, Phoca vitulina ...
The structural and functional organization of the pinniped eye, as represented by the harbour seal, Phoca vitulina, is much more complex than previously realized. The retina of the harbour seal is similar to that of the harp seal, in that it shows little zonation of the inner nuclear layer, possesse...
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| Format: | Text |
| Language: | English |
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University of British Columbia
2011
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| Online Access: | https://dx.doi.org/10.14288/1.0102098 https://doi.library.ubc.ca/10.14288/1.0102098 |
| Summary: | The structural and functional organization of the pinniped eye, as represented by the harbour seal, Phoca vitulina, is much more complex than previously realized. The retina of the harbour seal is similar to that of the harp seal, in that it shows little zonation of the inner nuclear layer, possesses large horizontal cells, and has similar nuclear densities within the different retinal layers throughout the retina. The outer nuclear layer is the thickest of all the retinal layers. Photoreceptor cells of types B and C were observed with a ratio of roughly 1:23 respectively. This ratio and photoreceptor density along with a well-developed and extensive tapetum, indicates a highly light-sensitive retina. The existence of retinal folding in marine mammals is also questioned and discussed. Refractive observations obtained through retinoscopy show that the harbour seal eye is very myopic and astigmatic in air, and hypermetropic with no discernable astigmatism in water. The axis of least corneal curvature is ... |
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