Fig. 4.

TEM micrographs of normal (A) and keratoconic button 1 (B–F) cornea using tannic acid staining. Normal cornea contains a concentration of MBs anterior to DM (A), with longitudinally sectioned structures showing a ∼60 nm periodicity. In keratoconic cornea (B), a small number of MBs were located in the posterior and middle stroma after extensive searching (black arrows). Many vacuoles were discovered at the border between basal epithelium (Epi) and stroma (C) with the absence of basal lamina and Bowman's layer. Many MBs were seen directly below the basal epithelium (white arrows) (D–F), concentrated in a 5 μm region (blue arrow). These were oriented longitudinally and transversely (inset – scale bar 0.5 μm). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)