PROTEIN GENE-PRODUCT 9.5-IMMUNOREACTIVE NERVES AND CELLS IN HUMAN ORAL-MUCOSA

Background: Current conflicting information on the innervation of the human oral cavity indicates technical problems such as different detec tability of the neural structures according to the various staining me thods used and difficulties in reproducibility. The possibility of int raoral regional differences has not been properly considered. Methods: Human biopsies of mucosa from different intraoral regions were prepar ed for immunohistochemistry using protein gene product 9.5 (PGP 9.5; a marker for neuronal structures). Results: Nerves were found consisten tly in all the biopsies. The neural pattern showed clear regional diff erences. Intraepithelial nerve fibers were found in the gingiva, labia , palate, within certain fungiform papillae, and in some salivary excr etory ducts. Organized nerve endings were found in varying frequencies in all but one (sublingual) region, appearing as lamellar (Meissner-l ike), coiled or glomerular neural structures, Merkel cell-neurite comp lexes were observed in the buccal, gingival, and palatal epithelia. Im munoreactive cells with many similarities to Merkel cells but without a neural connection were also encountered. Conclusions: Conflicting re sults from earlier innervation studies of the oral cavity could be att ributed to regional innervation differences. The distribution of the n erves also casts doubt on some of the present theories concerning the function(s) of intraoral nerves, such as the free nerve endings and th e Merkel cell-neurite complexes. (C) 1996 Wiley-Liss, Inc.