Immunohistochemical localization of collagen types I, III, and IV, laminin, fibronectin, and keratin in the endolymphatic sac.

We have employed immunohistochemistry to obtain baseline information on the molecular constituents of the extracellular matrix (ECM) of the endolymphatic duct (ED) and endolymphatic sac (ES) of the chinchilla. The results demonstrated that collagen types I and III were distributed in the subepithelial layer in the ED and ES, type IV collagen and laminin in the basement membranes, and fibronectin in the subepithelial layer and partly in the conglomerated cells in the ES. Collagen type III was diffusely distributed in the whole subepithelial layer of the ES, whereas collagen type I was concentrated densely in the deep layer of the interstitium, although gradually, the cuboidal epithelium in the ES was transformed into a flatter type in the ED. The epithelial cells of the ED and ES were clearly positive for keratin. This study deals, in particular, with the normal distribution of ECM components of the ED and ES of the chinchilla.

Distribution of endothelin-1 like activity in the endolymphatic sac of normal guinea pigs.

Endothelin-1 (ET-1), originally characterized as a 21-residue vasoconstrictor peptide from endothelial cells, has been reported to act as a local hormonal regulator of pressure, fluid, ions as well as neuropeptides. The present study investigated the distribution of ET-1 in the endolymphatic sac and duct of normal guinea pigs, by immunohistochemistry. ET-1 like activity was identified in the epithelial cells and subepithelial connective tissue of the endolymphatic sac and duct. No significant difference was seen in the intermediate and proximal portions. These findings suggest that ET-1 may play an important role in the regulation of inner ear pressure, fluid volume, and ion balance.

Differential immunohistochemical detection of cytokeratins and vimentin in the surgically removed human endolymphatic duct and sac.

Immunohistochemical detection of intermediate filament proteins and different subgroups of cytokeratins (Cks) was used to characterize the epithelium of the surgically removed adult human endolymphatic duct (ED) and sac (ES). The epithelium of the ED and ES demonstrated immunostaining for Cks 7, 8, 14, 17, 18 and 19, a pattern typical of so-called "complex" or "mixed" epithelia. This is a remarkable finding, since this pattern differs strikingly from previously reported data on the adult human cochlea and vestibular labyrinth that demonstrated a Ck pattern typical of "simple" (or single-layered) epithelia. Furthermore, the epithelium of the ED and ES demonstrated co-expression of Cks and vimentin. The present data indicate that the epithelium of the ED and ES exhibits another type of epithelial differentiation and demonstrates a higher degree of complexity than the other epithelia in the adult human inner ear.