Abstract
Abstract: :
Purpose:To examine changes of corneal limbal cells in postnatal rats. Methods:1-, 4-, 7-, 10-day-old and 2-, 4-, and 6-week-old Wistar Kyoto rats were used. Transmission electron microscopy (TEM) study: The enucleated eyes were fixed in 4% glutaraldehyde and Caulfield osmium and embedded in Luveak 812. The conjunctiva, corneal limbus and cornea were examined by TEM (Hitachi H-300 and JEOL 2100). In situ hybridization study: Paraffin sections of the conjunctiva, corneal limbus and cornea fixed in 4% paraformaldehyde and 0.2% glutaraldehyde were examined by TUNEL assay. These sections were examined by light microscopy. Results:The number of epithelial layers at the limbus increased with time. From 1 day to 6 weeks of age we observed cells with nuclear division in the basal cell layer at the limbus. These cells were loosely connected forming larger intercellular spaces, and had many mitochondria and a few desmosomes. Such cells were not seen in the epithelium of the cornea and conjunctiva. Until 2 weeks of age, apoptotic cells stained with the TUNEL method were seen in the basal cells at the limbus. Conclusion:The cells with nuclear division and apoptosis might be specific cells like stem cells, which divide into corneal basal cells.
Keywords: 370 cornea: basic science • 443 in situ hybridization • 472 microscopy: electron microscopy