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KJ Al-Ghoul, JY Lu, JR Kuszak; Migration Patterns of Posterior Fiber Ends in Lenses with Y- Sutures . Invest. Ophthalmol. Vis. Sci. 2002;43(13):456.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To characterize structural parameters of the basal membrane complex (BMC) and to determine the arrangement and organization of posterior fiber ends during elongation/migration in lenses with branched sutures. Methods:Normal, juvenile (4-6 week old) Sprague-Dawley rat lenses (n=16) were utilized. Posterior fiber ends, or «footprints», were assessed on both whole mounts of lens capsules and on decapsulated lenses. Basal membrane area measurements were made from scanning electron (SEM) and confocal microscopic images. BMC depth, or thickness, was measured by confocal microscopic z-series’ of phalloidin-FITC labeled footprints. Organization of migrating fiber ends was assessed by SEM and confocal microscopy in four regions: 1) equatorial 2) lateral-posterior (peripheral to the extent of suture branches) 3) polar-posterior (within the extent of suture branches) and 4) at the suture branches. Results:The average posterior fiber end area as seen on decapsulated lenses by SEM was 88µm2. The average F-actin profile as seen on lens capsule whole mounts by confocal microscopy, was comparable in shape and size (avg. of 92µm2). The BMC of rat lens fibers extended 4.5µm from the capsule and was of consistent thickness in all regions examined. In the equatorial region, footprints were aligned in rows oriented toward the posterior pole, consistent with the arrangement of straight, meridional fibers. Initially, fiber ends within the lateral-posterior region were arranged in short irregular rows having variable orientation with respect to the posterior pole. The remainder of these ends and those throughout most of the polar-posterior region were randomly arranged. As the posterior fiber ends approached suture branches, they became aligned in short rows oriented at angles to the posterior pole. Conclusion:The results confirm that F-actin profiles demarcate the BMC of posterior fiber ends. Furthermore, elongating fibers follow defined migration patterns along the posterior capsule to their sutural destinations, whereas previous evidence indicates that anterior suture formation does not occur simultaneously or by a similar mechanism. This controlled process is crucial to the formation of ordered suture patterns, thereby minimizing their adverse effects on lens optical quality.
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