Regional variation in distribution of EGF receptor in developing and adult corneal epithelium.

Epidermal growth factor receptor has been localized to the proliferative cell layers in a variety of stratified squamous epithelia. In the current study, the rat cornea was used as an experimental model to determine if epidermal growth factor receptor is concentrated in epithelial stem cells. Epidermal growth factor receptor was localized using immunofluorescence microscopy in adult and neonatal (1-day to 4-week) rat corneas. Antibody binding to epidermal growth factor receptor was present in basal cells across the adult cornea but was more intense in the limbal zone. In rats 1 day to 1 week of age, the corneal epithelium consisted of one or two layer of cells that were intensely labeled by anti-epidermal growth factor receptor. Following epithelial stratification, which occurred just prior to eyelid opening (approximately 12 days), expression of epidermal growth factor receptor was greatly reduced in central corneal epithelium and gained an adult pattern by 3 weeks of age. Expression of epidermal growth factor receptor was also examined by incubating 1 mm slices of adult corneas with 125I-epidermal growth factor (4 nM) for 90 minutes, followed by washing and autoradiography. Basal cells in the limbal zone contained 4.5-fold more silver grains per cell than did basal cells in the central cornea. These data suggest that cells with high potential for proliferation, i.e. limbal basal cells and all basal cells in developing rats, express high epidermal growth factor receptor levels. High levels of receptor may allow these cells to be rapidly stimulated by growth factors to undergo cell division during development and following wounding in adult corneas.(ABSTRACT TRUNCATED AT 250 WORDS)