Figure I-36: Iris posterior epithelium. A, Iris posterior epithelium. The basal surface of the posterior epithelium faces the posterior chamber and the lens. A thin basement membrane is found on this surface (X 45,000). B, Numerous infoldings (a) also occur on the basal surface of the posterior epithelium. Note that the basement membrane (b) continues along without entering the infoldings of the cell membrane (X 60,000).