Stereociliary glycocalyx and interconnections in the guinea pig vestibular organs.

Stereociliary glycocalyx and interconnections in the guinea pig vestibular organs were investigated at the electron microscopic level by using the ruthenium red staining technique. This staining visualized the glycocalyx and ciliary interconnections as well as the contact zone between the sensory hair bundle and the otolithic membrane or the cupula. Glycocalyx was found over the entire length of the stereocilia and the kinocilium of the sensory cells as well as over the entire apical surface of the supporting cells, in the form of a fuzzy filamentous layer. The ciliary structures were found interconnected by different types of connections, such as between the kinocilium and the neighboring stereocilia, and connections between stereocilia. These connections all emerged from the fuzzy layer of the glycocalyx and were also stained identically by ruthenium red, and were therefore considered to be morphologically similar. In addition, the tips of the sensory hairs were firmly attached to the otolithic membrane or the cupula. These findings suggested that the glycocalyx in the cell lining serves as an anchoring structure for the mechanical coupling not only between the ciliary structures, but also between the sensory hair bundle and the otolithic membrane or cupula.