The Epithelium of the Human Endolymphatic Sac: Immunohistochemical Characterization (With 1 color plate)

Abstract

A panel of monoclonal and polyclonal antibodies has been used to study the epithelium of the extraosseous part of the human endolymphatic sac (ES) by immunohistochemistry. The ES epithelium reacted with several epithelial markers such as Lu-5, different anticytokeratins, antiepithelial membrane antigen, and anticarcinoembryonic antigen. Unexpectedly, all epithelial cells also revealed a strong positive reaction for the mesenchymal marker vimentin and for S-100 protein. ‘Neuroendocrine’, a neurosecretory antigen, and neuron-specific enolase reactivity was detected in a few epithelial cells. The results support the assumption that the ES epithelium is metabolically active and capable of secretion and resorption. These findings are in keeping with results of functional experiments in animals. The demonstration of neurosecretory antigen and neuron-specific enolase in some cells indicate that the epithelium may also have paracrine functions.

Human Endolymphatic Sac: Evidence for a Role in Inner Ear Immune Defence (With 1 color plate)

“…In a previous study, we have reported the presence of secretory immunoglobulin A (IgA) in the human ES [4,5]. Immunohisto chemical findings support the assumption that the human ES, like the gut, appears to have not only resorptive and secretory, but also immunologic and paracrine functions [2,[4][5][6], The present immunohistochemical study was designed to identify cells with immuno logical functions in the extraosseous part of the human ES.…”

“…Immunohistochemical studies of the human ES have shown that the epithelium of the ES is similar to a mesothelium which has both secretory and resorptive capabilities [2], We have demonstrated the presence of IgA and secretory component within epithe lial cells and in the lumen of the human ES [4,5], These findings led to the hypothesis that the ES has similar capabilities as the gut, which secretes IgA into the lumen [9].…”

“…The time interval between death and dis section of the extraosseous part of the ES with scalpel and scissors averaged 10 ± 9 h ( ± SD; range: 2-42 h). Case histories of the selected persons without clini cally known inner ear disease were available [1,2], None of the inner ears were histologically abnormal.…”

“…The immunohistochemical techniques [immuno fluorescence technique, peroxidase-antiperoxidase (PAP) technique, alkaline phosphatase-antialkaline phosphatase (APAAP) technique] used in this study have been described elsewhere [1,2,11,31].…”

Functional Morphology of the Human Endolymphatic Sac

“…This observation led to the assumption that the ES represents a metabolically active part of the inner ear and prompted further investigations [9,10], Sensitive immunohistochemical techniques allow to characterize the epithelium of the human ES and its asso ciated cell populations according to the stage of differenti ation, and to detect cellular antigens that might be related to the function of this part of the inner ear.…”