Cell surface variations of the human upper tarsal conjunctiva.

Fifteen specimens of the upper tarsal conjunctiva were obtained from subjects with biomicroscopically normal conjunctivae. Ten specimens were examined by scanning electron microscopy and five by transmission electron microscopy. This examination was performed to examine cells with variant surface morphologic appearance that may be signs of the initial changes typical of those seen in the diseased conjunctiva. Although most specimens had cells with a characteristic uniform distribution of microvilli, seven specimens had cells with nonuniform microvillar patterns. In these seven specimens, less than 5% of the cells showed these changes. Cell surface variations marked by reduced cell diameters and alterations in the microvillar distribution were categorized into two groups: cells with microvilli that were grouped together to form tufts of varying height and number, and cells with a single, centralized group of microvilli. These variations were seen with increased frequency in disease, and it is postulated that the microvillar changes described in this study represent a continuum of adaptive responses of cells to insult and disease.