Molecular biology of the vestibular system

Molecular biology of the vestibular system has been limited by a number of technical difficulties including fixation, decalcification of the temporal bone and the small size of specific structures relative to their surroundings. In situ hybridization histochemistry and immunoelectron microscopy allow the subcellular study of gene expression and gene products, respectively. We developed the methodologies necessary to apply these techniques to the central and peripheral vestibular systems. The central and temporal bone distributions of the neuropeptide calcitonin gene-related peptide (CGRP) mRNA and two genes coding for gap junction proteins, connexin C32 and C43 mRNA, were studied. The cellular distributions of these mRNAs are presented. In addition, examples of pre-embedding and postembedding immunoelectron microscopy are presented demonstrating the usefulness of these techniques in studying the subcellular localization of specific antigens. The ultrastructural innervation of the vestibular periphery by the efferent neuropeptide CGRP and ultrastructural evidence of glycoprotein secretion by the human endolymphatic sac is presented.