Nanoscale Topography of the Corneal Epithelial Basement Membrane and Descemet's Membrane of the Human

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Abstract
Quantitatively define and compare the nanoscale topography of the corneal epithelial basement membrane (anterior basement membrane) and Descemet's membrane (posterior basement membrane) of the human. Human corneas not suitable for transplantation were obtained from the Wisconsin Eye Bank. The corneas were placed in 2.5 m M EDTA for 2.5 h or 30 min. for removal of the epithelium or endothelium, respectively. After removal of the overlying cells, specimens were fixed in 2% glutaraldehyde and either examined in this state by atomic force microscopy only or dehydrated through an ethanol series and prepared for transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The subepithelial and subendothelial basement membrane surfaces have a similar appearance that consists of an interwoven meshwork of fibers and pores. Topographic feature sizes were found to be in the nanometer size range with the epithelial basement membrane features larger and less densely packed than Descemet's membrane features. The topographic features are fractile in nature and increase surface area for cell contact. With the use of the TEM, SEM, and AFM, a detailed description of the surface topography of corneal epithelial basement membrane and Descemet's membrane of the human cornea are provided. The significance of differences in corneal basement membrane topography may reflect differences in function of the overlying cells or may be related to differences in cell migration and turnover patterns between the epithelium and endothelium.