Scanning electron microscopy of the frog lens

We have studied the morphology of the frog lens by scanning electron microscopy (SEM). By using fixative solutions with various buffer concentrations, we have been able to find a proper combination which significantly reduces tissue shrinkage during fixation. This has allowed us to control the shrinkage and cracking of lens which were previously thought to result from the process of critical point drying. We can now examine by SEM the surface morphology of practically every lens cell in a single antero-posterior plane. Thus, for the first time the membrane surfaces of the lens epithelial cells (central, pregerminative, germinative and transitional zones), the elongating fibers, fibers through the varying depths of the cortex, and the aged nuclear fibers can all be examined and compared in a single lens. The ability to prepare the entire lens for morphological examination with minimized preparative artifacts is important to further studies where stereological measurements can be made to quantitate for example, total membrane surface area and the size of the extracellular space at various locations within the lens. A quantitative estimation of these parameters will result in a more accurate analysis of the electrical properties of the lens.