Selective and transient expression of a native chondroitin sulfate epitopein Deiters' cells, pillar cells, and the developing tectorial membrane

The tectorial membrane (TM) is an acellular connective tissue overlying the sensory hair cells of the organ of Corti. Association of the tectorial mem brane with the stereocilia of the sensory hair cells is necessary for prope r auditory function. During development, the mature tectorial membrane is t hought to arise by fusion of a "major" and "minor" tectorial membrane (Lim, Hear Res 1986;22:117-146), Several proteins and glycoconjugates have been detected in the developing TM; however, the specific molecules which mediat e fusion of the two components of the TM have not been identified. In the present study, a novel monoclonal antibody (TC2) that recognizes a n ative epitope on glycosaminoglycans enriched in chondroitin-4-sulfate revea led a transient and restricted expression in the developing gerbil TM. The localization patterns suggest that Deiters' and pillar cells secrete a TC2- positive matrix prior to birth that later becomes incorporated into the mar ginal band and superior layer (cover net) of the TM. The developmental time course and patterns of TC2 reactivity suggest that this molecule may play a critical role in the fusion of the minor TM with the major TM. Anat Rec 25 6:64-71, 1999. (C) 1999 Wiley-Liss, Inc.