Regional distribution of alpha9beta1 integrin within the limbus of the mouse ocular surface.

The epithelial basal cells of the corneal limbus are known to contain adult corneal epithelial stem cells, but the properties of these cells are not well understood. In addition, how and when the limbal epithelium forms during postnatal development in mammals is not clear. To better understand the anatomy and cell biology of the limbus, a whole-mount procedure was used to show that the nasal, inferior, temporal, and superior regions of the mouse limbus contain different numbers of alpha9 integrin-positive cells most of which are observed in the nasal region. We also show that this pattern develops progressively over time from 1 to 8 weeks after birth. High magnification image projections and three-dimensional reconstructions of the limbal region were generated from confocal images obtained after tissues were dual stained with alpha9 integrin and propidium iodide (PI) or triple stained with alpha9 integrin, E-cadherin, and PI. Data show that alpha9 integrin is present on the adult mouse cornea in the limbal basal cells and is more abundant in the apical-most cytoplasm of the limbal basal cells, where it can be found colocalized within the plasma membrane with E-cadherin. These studies are an important step toward improving our understanding of the development and cell biology of limbal basal cells.