Fig. 6.

Immunofluorescence micrographs of BrdU in rabbit ocular surface epithelia. (A,B) Palpebral conjunctiva. The location of the mucocutaneous junction (mcj) is indicated. Arrowheads point to some of the Goblet cells. Frame A shows a representative section from the rabbit subjected to 10 days of BrdU treatment. About 50% of the cells incorporate label (yellow-green fluorescence). Labeling extends to the suprabasal compartment indicating the rapid nature of cell turnover and stratification in this epithelium. Frame B shows an equivalent section from the animal subjected to a 38-day BrdU chase. Label is scant. Within the proliferative basal layer BrdU is present in cells in the Goblet cell-rich zone but it is essentially absent within the basal cells of the highly layered and Goblet-cell free zone proximal to the mucocutaneous junction. (C) Fornical conjunctiva of the same specimen shown in B. In this area the epithelium presents a lobular-like organization and displays substantial BrdU retention in basal cells. (D,E) Sections incorporating bulbar conjunctiva and the limbal (Li) and central corneal (Co) zones. There is substantial BrdU incorporation in all three domains (D). Following the 38-day chase, strong BrdU retention is seen only in the cells of the limbus (E). Bar, 100 μm.