Abstract
Purpose :
The current study aimed to characterize the 3D nuclear morphometry of lens epithelial cells in the central zone using serial block-face scanning electron microscopy (SBF-SEM).
Methods :
Lenses were obtained from six-week-old female albino Sprague-Dawley rats and extracted. The epithelial volumes within the central zone were isolated and fixed using 2.5 % Glutaraldehyde. After fixation, the tissue was trimmed into small blocks and embedded in resin for serial sectioning. SBF-SEM was employed to image the specimens, resulting in a stack of images with a section thickness of 200 nm. The field of view was set to 45 µm yielding a pixel resolution of 14.6 nm. Segmentation of epithelial nuclei was performed in each image. Considering the section thickness, the 3D volume of the nuclei were reconstructed. Finally, morphometric parameters of the nuclei were determined.
Results :
A 95 % confidence interval (CI) for the mean nuclear volume of epithelial cells in the central zone was shown to be 223±15 µm3. After fitting each nucleus to an ellipsoid, the semi-major axis, semi-intermediate axis and semi-minor axis, respectively, were determined at 95 % CI to be 6.7±0.9 µm, 4.7±0.4 µm and 1.7±0.1 µm. The semi-major and semi-intermediate axes were approximately oriented parallel to the capsule, with the semi-minor axis aligned to the sagittal axis. Nuclear deformations, such as finger-shaped extrusions and invaginations, were observed.
Conclusions :
The application of SBF-SEM unveils three-dimensional morphological characteristics of nuclei in lens epithelial cells. Within the central zone, the nuclei exhibit a tri-axial ellipsoidal shape, elongated along the lens capsule, with volumes of comparable magnitude. The observed nuclear extrusions and intrusions suggest potential exo- and endonucleotic exchanges between the cytoplasm and the nucleus.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.