Cupula, Cupular Zone of Otolithic Membrane, and Tectorial Membrane in the Squirrel Monkey

Abstract

The microscopic architecture of the cupula was studied in subhuman primates. It was determined that the cupula has a honeycomb-like mesh-work and that this meshwork may contain both neutral and acid poly-saccharides, as well as mucoprotein. The nature of the contents in the space enclosed by this meshwork is not certain although the existence of a small amount of acid mucopolysaccharide is suggested. The cupular zone of the otolithic membrane was stained both by PAS and alcian blue, similar to the cupular meshwork, but the subcupular zone was not stained either in the cupula or the otolithic membrane. The border of the tectorial membrane reacted very strongly to both PAS and alcian blue stainings. Within the tectorial membrane the contents reacted moderately. The fibrils in the tectorial membrane seemed to be stained darker than the surrounding components, suggesting neutral and acid mucopoly-saccharides and mucoprotein. These findings suggest that the meshwork of the cupula, the cupular zone of the otolithic membrane, and the tectorial membrane have basically identical chemical components.