Continuous variation of fiber cell size, shape and ordering in the equatorial plane of bovine lenses

Purpose. A rapid means was sought to visualize and quantify the cross-sectional areas of fiber cells, the variations of cell area and the regularity of packing in the equatorial plane of normal adult bovine lenses. Methods. Normal bovine lenses (approximately 2-3 years old) from a local arbitoire were Vibratome sectioned either parallel or perpendicular to the optic axis. Fresh Vibratome sections were examined by phase contrast, DIC and laser scanning confocal microscopy. Alternate sections were fixed and prepared for examination at both the light and electron microscopic levels. Image analysis was performed to determine the cross-sectional areas of fiber cells in selected nuclear regions. Results. Thin section transmission electron microscopy revealed a pattern of cell size and shape in each region which was similar to that recently reported for normal human lenses (Taylor et al., IOVS 36, S261, 1995). In the equatorial plane of bovine lenses, average cross-sectional areas were 7 ± 2 μm2 in the adult nucleus, 32 ± 18 μm2 in the fetal nucleus and 55 ± 28 μm2 in the embryonic nucleus. Because the ultrastructural results were time consuming and technically difficult to obtain, we developed light microscopic methods to more quickly acquire structural details. Fiber cell measurements from light microscopic techniques were comparable to those derived from ultrastructural analysis. Moreover, the distribution of cell sizes and the number of cell layers was readily available for each region. Overviews of the equatorial plane demonstrated a gradual improvement in the regular packing of radial cell columns proceeding from the relatively disordered embryonic and fetal nuclei through the well-ordered adult nucleus to the highly regular cortical region. Conclusions. Light and electron microscopy reveal the highly irregular packing and large average size of cells in the embryonic nucleus and the gradual reduction in size and progressive improvements in regularity of packing in the outer layers. The light microscopic methods used here have the advantage of rapidly giving a continuous view of the fiber cell structure and arrangement which is not available using electron microscopy.

Duke Scholars

Author Martin Joseph Costello III Ophthalmology