[Proliferative ability and ultramicrostructure of basal limbal epithelial cells in different age group of normal...

To demonstrate the difference in proliferative ability and ultramicrostructure of basal limbal epithelial cells in different age group of normal subjects.

It is a case-control study.40 specimens of limbus from 40 eyes provided by the eye bank of Eye Ear Nose and Throat Hospital of Fudan University in 2007 - 2008 were enrolled in this study. Only one eye was enrolled from the same donner. Specimens were divided into 4 groups according to the donners' age: A (0 - 19 years), B (20 - 39 years), C (40 - 59 years) and D (60 - 79 years). Immunohistochemistry of proliferating cell nuclear antigen (PCNA) was performed on 10 specimens of each group. The staining status of limbal epithelium was observed and the staining positive rate of the limbal basal epithelial cells was graded. And transmission electric microscopy was performed on specimens of each group. The morphologic feature of the ultramicrostructure of limbal basal epithelial cells were observed.

50% of specimens in group A showed a strong PCNA staining of (++++), while a weak staining of (+) took a main part in all the other 3 groups (B 40%, C 60% and D 50%, respectively). Furthermore, positive nuclear staining of limbal superficial cells was observed in 3 specimens and positive cytoplasm staining was observed in 1 specimen, all in group A. Transmission electric microscopy showed that the stem cell-like cells in group A possessed 3 morphologic features: extremely small, stretching along the basal membrane, with densely packed heterochromatin. In contrast, the stem cell-like cells in the other 3 groups did not show great disparity in cell size with their neighbor epithelial cells, and they stretched vertically to the basal membrane, with dispersed euchromatin.

Difference in proliferative ability and ultramicrostructure of basal limbal epithelial cells was found in different age group of normal subjects.