CELL-CYCLE KINETICS IN PTERYGIUM AT 3 LATITUDES

The cell cycle kinetics of 93 specimens of pterygial tissue, as well a s 19 specimens of normal conjunctiva, from patients at three sites rep resenting three different latitudes (Singapore, 1 degrees; Hong Kong, 22 degrees; and Little Rock, Arkansas, 34 degrees) were evaluated by f low cytometry. The results showed no difference in cellular proliferat ion patterns between pterygial and conjunctival tissue at any of the s ites, suggesting that pterygium is not a disorder of excess cellular p roliferation. Transmission electron microscopy showed extracellular ma trix to be a prominent component of pterygium. Cellular proliferation patterns of primary and recurrent pterygium were not significantly dif ferent from each other. Factors associated with increased incidence of pterygium included male sex, outdoor occupation, and advanced age.