Abstract
Purpose: :
To investigate and visualize cataract morphology and repair, after unilateral in vivo exposure to double threshold dose UVR-B in the C57BL/6 mouse lens.
Methods: :
20 six weeks old female mice received in vivo double threshold dose (6.4 kJ/m2) UVR-B for 15 minutes. The radiation output of the UVR- source had MAX at 302.6 nm. After a latency peroid of 24, 48, 96, and 192 hours following UVR-B exposure the induced cataract was visualized with electron microscopy techniques. Damage to the lens epithelium and the anterior cortex was investigated with light microscopy in toluidine blue statined semithin sections, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dark field illumination photography.
Results: :
UVR-B exposed lenses developed anterior subcapsular, and/ or cortical and nuclear cataract after 24 hours. Lens epithelial cell damage was seen in TEM as apoptotic cells, apoptotic bodies, nuclear chromatin condensation, and swollen and disrupted anterior cortex fibers. These morphologic changes pronounced to the anterior third of the lens were also visualized with SEM. Over the observed latency period anterior subcapsular cataract was repaired towards the anterior sutures as documented with dark field illumination photography.
Conclusions: :
UVR-B induced cataract in the mouse lens is morphologicaly pronounced to the anterior third of the lens. Damage to the epithelium and anterior cortex in the mouse lens is repaired by epithelial cell movement towards the lens sutures thus in retrograde direction to regular epithelial cell differentiation.
Keywords: cataract • microscopy: electron microscopy • apoptosis/cell death