title: The eyelid margin: a transitional zone for 2 epithelial phenotypes.
abstract: OBJECTIVE
  To investigate the differentiation profile of the epithelium of the eyelid margin in the primate.
  
  
  METHODS
  The expression of cytokeratins (CKs) CK1/10, CK4, CK14, CK5/8, and CK19; involucrin; connexin 43; filaggrin; and muscarinic receptor subtypes (m1-m5) on eyelid tissues from adult Macaca fascicularis (n = 3) was studied by immunohistochemistry.
  
  
  RESULTS
  Cytokeratin 1/10, CK4, CK19, filaggrin, and connexin 43 expression varied across the epithelium of the mucocutaneous junction (MCJ). At the MCJ, CK4-positive cells overlapped basal CK14-expressing cells. The meibomian gland duct and the MCJ revealed layers of CK14-positive cells. Cytokeratin 5/8 was expressed in the basal layer of the epidermis and conjunctiva, while involucrin-positive cells were superficial. The m2 was expressed throughout the conjunctiva; m3 was found in the basal cells of the skin, conjunctiva, and alveolar epithelial cells of the meibomian glands; and m4 was expressed in the suprabasal layers of the skin.
  
  
  CONCLUSIONS
  The eyelid margin epithelium is formed from 2 different epithelial cell subpopulations with specific but overlapping distributions. The meibomian gland duct or MCJ may be a site of conjunctival progenitor cells.
  
  
  CONCLUSIONS
  This study provides a basis for understanding eyelid pathological conditions and eventually for developing methods for cellular reconstruction of the eyelid margin using expanded progenitor cells.
authors.affiliation: Singapore Eye Research Institute.
authors.forename: Shaohui
authors.initials: S
authors.lastname: Liu
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Donald T H
authors.initials: DT
authors.lastname: Tan
authors.forename: Roger W
authors.initials: RW
authors.lastname: Beuerman
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D003228:Conjunctiva / Q000166:cytology; D018031:Connexin 43 / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D005143:Eyelids / Q000166:cytology* / Q000378:metabolism; D000091344:Filaggrin Proteins; D019084:Fluorescent Antibody Technique, Indirect; D007381:Intermediate Filament Proteins / Q000378:metabolism; D007633:Keratins / Q000378:metabolism; D008252:Macaca fascicularis; D008856:Microscopy, Fluorescence; D010641:Phenotype; D011498:Protein Precursors / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology
chemical_list: D015415:Biomarkers; D018031:Connexin 43; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D011498:Protein Precursors; D011976:Receptors, Muscarinic; C032253:involucrin; D007633:Keratins