The Mucocutaneous Junction (MCJ)

The MCJ is the natural epithelial transition zone between skin and the ocular mucosa

The MCJ is located proximal to the epidermal cuff around the orifices of the Meibomian glands at the inner lid border and is followed by the lid wiper, which represents the initial thickening of the conjunctival mucosal epithelium. The MCI is a zone of gradual transition between the cornified oily-dry epidermis and the fully developed aqueous-moist conjunctiva.

Close inspections of histological specimens from the posterior lid margin shows that the morphology of the surface epithelium gradually develops from the underlying more basal cells. Deep layers close to the basement membrane show an appearance of cells and their nuclei that is compatible with the presence of stem cells and it had indeed been shown in the rabbit and human that there is a stem cell nice at the posterior lid margin. Due to the gradual differentiation of the surface epithelial cells of the MCJ from precursors in the deeper layers it is unlikely that the come into existence just by potential, imaginative surface influences such as e.g. evaporation, but in fact the MCJ is a specific epithelial zone of its own right with own stem cells and specific differentiation.