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S. Bassnett, P.A. Winzenburger; Morphometric Analysis of Fiber Growth in the Developing Chicken Lens . Invest. Ophthalmol. Vis. Sci. 2003;44(13):948.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: It is generally assumed that fiber cell differentiation proceeds identically in cells produced at different points in the life cycle. This implies that the fate of one cell can be predicted by examining the cell immediately beneath it. In this study, we tested this assumption directly, by examining the fate of identified populations of fibers over time. This allowed a direct comparison of the life histories of cells of different ages. Methods: Lens radii, cell length, shape, cross sectional area and perimeter, and cell packing organization, were measured from confocal and TEM micrographs of embryonic chicken lenses. Derived values for cell surface area and volume were also calculated. We used a novel coordinate system to track identified cohorts of cells at successive developmental stages. This allowed kinetic information, such as rate of increase in length or volume, to be derived. Results: The analysis revealed some previously unexpected features of fiber differentiation. For example, the posterior tips of fiber cells migrated more quickly than the anterior tips. The overall rate of fiber cell elongation (147 µm/day) did not vary with cell age. The rate of increase in cell membrane surface area (6280 µm2/day) was not diminished after cells completed their elongation. Instead, unabated membrane addition fueled the increase in lateral membrane complexity that occurred in sutured cells. A surprising degree of structural remodeling occurred during fiber cell elongation and continued after extant cells were buried by newly formed fibers. Even in anucleated cells, however, shape and membrane topology were altered continually during development. In contrast, certain aspects of fiber cell organization were established early in development and did not vary thereafter. For example, the packing arrangement of cells in the adult lens was traced to a cellular template established on the tenth day of embryonic development. Conclusions: Integrated morphometric analysis at successive developmental stages provides insights into the life history of fiber cells buried within the cellular conglomerate of the lens.
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