Abstract
Purpose: :
To measure the cell complement of the mammalian lens epithelium and to correlate cell dimensions, organisation and geometry relative to their location in order to understand the biological basis of lens size.
Methods: :
Lens capsules from a variety of different mammals, including human, were flat mounted and processed for confocal immunofluoresence microscopy. Image processing software was developed for the rapid and reliable counting of cells within these epithelial samples. Mouse, rat, bovine and human lens epithelia were studied. Rates of apoptosis and cell profiferation were determined by TUNEL labelling and Ki67 staining respectively. Cell boundaries were imaged using either phalloidin or lectin conjugates to allow cell volume and individual dimensions to be measured.
Results: :
Using both individual cell parameters as well as cell number measurements, the cell complement of the mammalian lens epithelial compartment for different epithelial zones such as the central, germinative and equatorial zones was calculated. Each zone within the lens epithelium has a characteristic cell profile, which was consistent between the different mammalian species. These data allow us to track the transition between the different zones. In the central region cells are 2-3 times shorter than epithelial cells at the lens equator, yet cell density in this region is the most sparce. We have calculated the cell complement in the epithelium from our measurements of cell density for the different zones. Our preliminary data suggest the proliferation rate in the lens epithelium is sufficient to support cell loss from this compartment. Our data set allows us to present a cell map for the lens epithelium.
Conclusions: :
The lens epithelium has distinct zones characterised by cell density and cell geometric profiles. This study has allowed us to reassess the dynamics of the epithelial cell complement and understand the complexity of cell organization within this tissue. These data are particularly relevant to understanding the cellular consequences of cataract surgery, where the phacoemulsification procedure removes the entire central zone which is key to maintaining cell homeostasis in this tissue.
Keywords: anatomy • cell survival • differentiation