[The ultrastructure of utricular maculae of mouse]

Objective: Using scanning electron microscope to observe the ultrastructure of utricular maculae of mouse. Methods: Ten young (6 to 8 weeks) and ten old (>12 months) mice were executed, and their utricles were harvested and the specimens were processed, using scanning electron microscope to observe the structures of the utricles from the surface of otoconia layer to the roots of hair cell cilia. Results: Under the scanning electron microscope, several ultrastructures were observed, including otoconia layer, unstructured gelatinous extracellular matrix layer, honeycomb-like gelatinous extracellular matrix layer, inter-cilia otoconia and hair cell cilia associated with these structures. When compared with young mouse, the otoconia surface of aged mouse was smoother, the gelatinous extracellular matrix between the adjacent otoconias was thinner. Conclusions: Using SEM, ultrastructures can be clearly observed from surface otoconia layer to the roots of hair cell cilia. By the analysis of the ultrastructure of utricular maculae, it is helpful for investigation of the pathological mechanisms of vestibular diseases, such as otolith diseases.