Connexin 26 distribution in gap junctions between melanocytes in the humanvestibular dark cell area

We have previously demonstrated the presence of gap junctions between melan ocytes in the human vestibular organ and have speculated that melanocytes f unction in maintaining the homeostasis of the microenvironment of the inner ear. The purpose of the present study was to characterize the expression a nd ultrastructural localization of connexin (Cx) protein in melanocytes of the human vestibular organs. Surgical material was obtained from patients o perated on for vestibular schwannoma and was processed for light microscopy , confocal laser scanning microscopy, conventional TEM, and immune TEM. The specimens were labeled with anti-Cx26, Cx32, and Cx43 antibodies and exami ned by light microscopy. Specimens were also labeled with anti-Cx26 antibod y and examined by laser microscopy and immuno-TEM methods. The specimens ex amined in this study were mainly dark cell areas from the human vestibular organ, whose epithelial and subepithelial layers are rich in melanocytes. L ight-microscopic immunohistochemical studies showed positive labeling for C x26 protein between subepithelial melanocytes, and Cx32 was also detected. Use of anti-Cx26 antibody and confocal laser scanning microscopy revealed h igh levels of Cx26 around the subepithelial melanocytes. Post-embedding imm une-gold transmission electron microscopy showed significant aggregation of gold particles (33.97 +/- 8.01% of total gold particles) around the gap ju nctions of the subepithelial melanocytes. The results of this study indicat ed that melanocytes are connected through gap junctions that mainly contain Cx26. This suggested that the melanocytes in the human vestibular organ ma y play a role in transporting material between the endolymph and perilymph. Anat Rec 262:137-146, 2001. (C) 2001 Wiley-Liss, Inc.