FIGURE 3.

Gross malformation of the vestibular gravity receptor. A, wild-type otoconia can be easily detected under a light microscope when looking at isolated inner ears. Two bright reflected areas represent the otoconia of the saccule and utricle of newborn mice. Slc26a4^loop mutant mice lack the bright reflection, and instead, a dark hole appears when looking through the oval window (arrowheads). B, SEM of 2-month-old utricle shows thousands of otoconia (inset) that cover the sensory epithelium in a wild-type mouse, whereas a giant stone is appearing at Slc26a4^loop/loop utricle. C, imaging of the gelatinous matrix (otoconial membrane) reveals its normal structure in wild-type mice, which is characterized by typical pores. In Slc26a4^loop mutants, the otoconial membrane is dissociated and severed. D, high resolution images of the underlying hair cells show that Slc26a4^loop/loop vestibular hair cells appear to be normal. Scale bars equal 500 μm in panel A, 100 μm in B, 5 μm in C and D. n = 4.