The Statoconial Membrane of the Guinea Pig Utricular Macula: Scanning Electron Microscopic Investigation Combined with the Freeze-fracturing Technique

Abstract

The superstructure of the guinea pig utricular macula was investigated using scanning electron microscopy combined with the freeze-fracturing technique. The statoconial membrane was composed of the otoconial layer, otolithic membrane and subcupular meshwork. The otolithic membrane consisted of closely arranged filaments with beaded appearance and densely packed globular matrix near the otoconial layer. The subcupular meshwork consisted of long branching filaments cross-bridged to one another. The filaments were continuous with those of the otolithic membrane on one side and with the surface of the epithelium on the other, which fills the space between the otolithic membrane and the macular surface. The otolithic membrane would function as a rigid plate and equally distribute the shear force of the otoconial layer to all the ciliary bundles. The subcupular meshwork may play an important role in transmitting the shear strain of the otolithic membrane to all the ciliary bundles and may also exert an additional dampening effect to prevent unwanted vibration.

Key Words:

• otolithic membrane
• utricular macula
• guinea pig
• SEM
• freeze-fraclure