Cross sections of vestibular organs from B6.MRL-Atp6v1b1vtx/vtx and MRL-Atp6v1b1vtx/vtx mice. (A, B) Both B6.MRL-Atp6v1b1vtx/vtx (A) and MRL-Atp6v1b1vtx/vtx (B) mutant cristae appear normal (posterior cristae is shown), including presence of cupula, hair cells, and dark cells. (C–F) B6.MRL-Atp6v1b1vtx/vtx maculae (saccule shown in C) appear normal. MRL-Atp6v1b1vtx/vtx mutant maculae (saccule is shown in D-F) show normal complement of hair cells, but few, very large otoconia that tend toward triangular shapes. Possible macrophages (arrows in D) line the epithelial surface and surround abnormal otoconia. Scale bar in A applies to all panels. Cup, Cupula; HC, Hair cells; DC, Dark cells; Ot, Otoconia.