Purpose. In the limbo-corneal epithelium the stem and early precursor epithelial cell pool is confined to the limbal rim. Among the features associated with this spatial segregation is the general paucity of connexin43 (Cx43) within the limbal basal cell population and its complete absence in resident stem cells. The limbo-corneal epithelial lineage derives from a Cx43-positive (Cx43(+)) embryonic outer ectoderm. Accordingly, as a means of identifying the process through which limbal cell phenotypes emerge, we investigated the expression of Cx43 in the ocular surface of embryonic rats.