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P. G. O'Brien, E. Y. Liu, C. F. Wildsoet; Ultrastructural Characterization of Normal and Albino Guinea Pig Sclera. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3594. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the sclera of normal and albino guinea pigs, which represent one of two mammalian models used in myopia research.
Transmission electron microscopy (TEM) images were used to assess scleral thickness and collagen fiber diameters in samples of posterior sclera from one normal and one albino guinea pig, both 23 weeks old. Five images from each animal were chosen at random, and a total of 1326 and 1495 collagen fibers were analyzed from the middle region of sections from normal and albino animals respectively. Measurements were made using NIH ImageJ software and the distance tracking feature of the Adobe Photoshop line tool. Immunocytochemistry for alpha smooth muscle actin (α-SMA) was performed using an avidin-biotin peroxidase complex technique on scleral fibroblasts cultured from a normally pigmented animal.
For the normal and albino animals, the respective scleral thicknesses were 94.8 µm ± 9.09 and 128.7 µm ± 5.76 µm, and the respective median diameters of the collagen fibers were 160 nm and 122 nm. Star-shaped collagen fibers were evident only in sclera from the albino animal. Fibroblasts were present as a sparse population, sandwiched between collagen lamellae, in both cases. Cultured scleral fibroblasts were immunopositive for α-SMA.
The sclera of the pigmented guinea pig is qualitatively similar to the sclera of the tree shrew. There are differences in collagen fiber organization that exist between normal and albino guinea pig scleras. The organization of collagen fibers in albino guinea pig sclera is reminiscent of that reported in the sclera of form-deprived myopic tree shrew eyes,1 and thus consistent with the more aberrated and relatively myopic eyes of albino guinea pig eyes.2 1. McBrien NA, Cornell LM, Gentle A. Structural and ultrastructural changes to the sclera in a mammalian model of high myopia. Invest Ophthalmol Vis Sci. 2001 Sep;42(10):2179-87.2. Wang JY, Liu SZ, Wei X, Wu XY, Tan XP. [High myopia and retinal ultrastructure of albino guinea-pigs]. Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2007 Apr;32(2):282-7. Chinese.
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