A unique lineage gives rise to the meibomian gland

PURPOSE To identify the lineage that contributes to the morphogenesis of the meibomian gland. METHODS To examine which cell lineage gives rise to the meibomian gland, the expression of Pax6 as well as that of various cytokeratin markers, including keratin 14 (Krt14), Krt15, Krt4, and Krt10, was examined with immunofluorescent staining of C57BL/6J mouse eyelids from P2 to P11 pups and adult mice. RESULTS Pax6 was localized to the cytoplasm within the acinar region of the meibomian glands during morphogenesis but was absent in the fully developed gland. Keratin 14 was expressed throughout the gland at all stages whereas keratin 15 was absent at all stages. Keratin 4, a marker of mucosal lineage, was present throughout the gland and was colocalized with keratin 10 (epidermal lineage marker) in the developing duct at P4. This colocalization region decreased as the gland developed becoming restricted to the central duct near the opening to the acini in the fully developed gland. CONCLUSIONS We identified a unique cell lineage that expresses markers characteristic of mucosal and epidermal epithelia during meibomian gland morphogenesis. This unique group of cells was located in the central duct with a concentration near the ductule orifice. The expression of these cells reduced during meibomian gland morphogenesis and may play a role in the development and homeostasis of the gland.