Technique for transmission and immunoelectron microscopy of the human endolymphatic sac and vestibular epithelia

A surgical technique is presented to obtain the entire vestibular aqueduct, containing the endolymphatic duct and sac as well as the vestibular epithelia, from the maculae and cristae during labyrinthectomy. The inner ear tissue was fixed in 3% glutaraldehyde, decalcified in 0.1 mol/L Na-EDTA, and routinely processed for transmission electron microscopy, including post-fixation with osmium tetroxide. Postembedding protein A-colloidal gold immunoelectron microscopy was performed after exposure of cellular antigenic sites by sodium metaperiodate. To validate this technique, thin sections from the crista ampullaris and the endolymphatic sac were incubated with antibodies raised against S-100, a protein present in specific types of neural tissue. Specific immunoreactivity was observed in the crista ampullaris, but not in the endolymphatic sac. The surgical biopsy technique described provides a means for the neuro-otologist to collect inner ear tissue from surgical patients that can be used for pathological studies using immunohistochemistry and electron microscopy.