Scanning electron microscopy of normal human corneal epithelium obtained by scraping-off in vivo

The surface of normal human corneal epithelium was examined by scanning electron microscopy (SEM). The study was carried out on specimens obtained by scraping-off in vivo, and immediately fixed. Four different types of microprojections were observed on the epithelial surface: microridges, microvilli, tufted microvilli and knobs. Detailed high magnification of surface microprojections showed that they consist of subunits. Our data suggest a correlation between surface morphology and maturity of the corneal epithelial cell. An evolutive sequence is proposed, from the youngest cell, provided with microridges, to the oldest exfoliating one, with knobs.