A study of otoconia of normal mice and shaker mice

Otoconia from the maculae of the utricule and the saccule of normal mice and shaker mice have been examined by means of polarizing microscopy and scanning electron microscopy. X-ray dispersive analysis was used to determine the elements present in the crystals. The otoconia were found to be negative birefringent crystals. They are among the largest crystals found in mammalian tissues, many being 30-50 microns in length and 109-20 microns in diameter. The majority were calcite (calcium carbonate) crystals. Some crystals had a different morphological appearance and contained phosphorus (phosphate compound) as well as calcium. The phosphate content was much less and sometimes absent from utricular otoconia of shaker mice.