Development of conjunctival goblet cells and their neuroreceptor subtype expression

PURPOSE. To investigate expression of muscarinic, cholinergic, and adrenerg ic receptors on developing conjunctival goblet cells. METHODS. Eyes were removed from rats 9 to 60 days old, fixed, and used for microscopy. For glycoconjugate expression, sections were stained with Alcia n blue/periodic acid-Schiffs reagent (AB/PAS) and with the lectins Ulex eur opeus agglutinin I (UEA-I) and Helix pomatia agglutinin (HPA). Goblet cell bodies were identified using anti-cytokeratin 7 (CK7). Nerve fibers were lo calized using anti-protein gene product 9.5. Location of muscarinic and adr energic receptors was investigated using anti-muscarinic and beta-adrenergi c receptors. RESULTS. At days 9 and 13, single apical cells in conjunctival epithelium s tained with AB/PAS, UEA-I, and CK7. At days 17 and 60, increasing numbers o f goblet cells were identified by AB/PAS, UEA-I, HPA, and CK7. Nerve fibers were localized around stratified squamous cells and at the epithelial base at days 9 and 13, and around goblet cells and at the epithelial base at da ys 17 and 60. At days 9 and 13, M-2- and M-3-muscarinic and beta(2)-adrener gic receptors were found in stratified squamous cells, but M-1-muscarinic a nd beta(1)-adrenergic receptors were not detected. At days 17 and 60, M-2- and M-3-muscarinic receptors were found in goblet cells, whereas M-1-muscar inic receptors were in stratified squamous cells. beta(1)- and beta(2)-Adre nergic receptors were found on both cell types. beta(3)-Adrenergic receptor s were not detected. CONCLUSIONS. In conjunctiva, nerves, M-2- and M-3-muscarinic, and beta(1)- and beta(2)-adrenergic receptors are present on developing goblet cells and could regulate secretion as eyelids open.