Histochemical analysis of secretory vesicles in nongoblet conjunctival epithelial cells

Abstract. An Alcian‐blue/Periodic acid Schiff reagent (AB/PAS) pH dependent staining method was used to identify the mucus content of secretory vesicles of nongoblet epithelial cells of the human conjunctiva. Twenty subjects were selected for biopsy of the midcentral upper tarsal conjunctiva: 10 subjects had no contact lens wearing experience, and 10 subjects wore contact lenses. Human respiratory epithelium was used as a control for the staining procedure. Four‐micron paraffin sections of conjunctival and control tissues were stained with Alcian blue at pH 2.5 and 1.0 and counterstained with PAS. Non‐goblet epithelial cell secretory vesicles contained neutral mucin, sialmucin, and sulphomucin. This study provides evidence for a ‘second’ mucus system of the conjunctiva, that this system is in the non‐goblet epithelial cells, and that the mucus of this system has sulphomucins, sialomucins and neutral mucins.