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Kristin J. Al-Ghoul, Dana K. Williams; Secondary Suture Branch Formation in Rat Lenses. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1537.
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Our prior investigations have revealed that secondary suture branches develop in rat and guinea pig lenses. The present study was conducted to further evaluate the anatomy and progression of suture pattern changes in the rat lens as a function of growth and aging.
Lenses from juvenile (n=32), adult (n=42) and aged (n=32) Sprague-Dawley rats were utilized. Following enucleation, anterior and posterior surfaces of unfixed lenses were examined and photographed under a dissecting microscope. A grading system was developed to assess the position, number and linear integrity of both primary and developing secondary suture branches wherein a score of ‘0’ indicated an unmodified Y-suture and a score of 1-6 indicated increasing deviations in the regularity, position and number of suture branches.
Lenses from juvenile (3-12 week old) rats had an average score of 1.48 posteriorly and 0 anteriorly. Adult rat lenses (13-51 weeks old) had average scores of 1.66 and 0.79 on the posterior and anterior, respectively. In aged rat lenses (52+ weeks), the average posterior score was 2.83 and the average anterior score was 1.18. Alterations to posterior sutures began as early as 4 weeks, progressed gradually and their development appeared to be correlated with increased age. Grossly, posterior Y suture patterns were eventually overlain with an X pattern, which, with advanced age, developed additional partial sub-branches (incomplete star pattern). Anterior Y suture patterns, by contrast, were virtually unchanged throughout the juvenile stage. Adult lenses subsequently developed partial anterior secondary suture branches to form an incomplete X pattern. Only rarely were multiple secondary sub-branches observed in the most aged lenses.
The data indicates that non-primate mammalian lenses are capable of developing successive iterations of suture patterns as a function of growth and aging. In rats, both anterior and posterior secondary branches form in a similar fashion, but at a slower rate anteriorly. This suggests that the migration/targeting of anterior and posterior fiber ends occurs independently.
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