Ultrastructural morphology and protein content of the internal organic material of rat otoconia.

Otoconia taken from the maculae of the saccule and utricle of the rat inner ear were investigated using transmission electron microscopy (TEM). Their ultrastructure was compared using various decalcification techniques. Similar preparations were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to assess their protein constituents. TEM results show loss of organic material during prolonged decalcification. This is not seen in samples decalcified overnight. The SDS-PAGE results show that rat otoconia contain a major broad band of 90-100 kDa, a major thin band of 56 kDa, and three other bands of 33, 45, and 50 kDa. The band of 56 kDa may be associated with the surface of the otoconia.