vestibular malformation in mice lacking nak2cl cotransporter 1 and expression of nak2cl cotransporter 1 in human vestibular end organs conclusion the nak2cl cotransporter1 nkccl may be essential for the maintenance and functioning of the vestibular morphology in mice and it is strongly expressed in human vestibular end organsobjective nkccl is a member of the cationcoupled chloride transporter which participates in salt transport and cell volume regulation in diverse tissues nkccldeficient mice exhibit deafness and show structural alterations in the cochlea in addition to hearing loss nkccldeficient mice show a shakerwaltzer behavior which suggests a vestibular system defect in this study we investigated the morphology of the vestibular system of nkccldeficient mice and also evaluated whether nkccl mrna and its protein are expressed in human vestibular end organsmaterial and methods nkccldeficient and wildtype mice aged 45 weeks were sacrificed their heads were cut in the midsagittal plane fixed and decalcified for light microscopy 5microm sections were cut and stained with hematoxylineosin human vestibular end organs were harvested during acoustic tumor surgery via a translabyrinthine approach some of these end organs were used for total mrna extraction and the remainder for immunostaining reverse transcriptase polymerase chain reaction and immunostaining were performed for nkcclresults the scala media of the cochleae of the nkccldeficient mice had collapsed but the bony labyrinth appeared unaffected however the semicircular canals sccs were much smaller than those in the wildtype mice furthermore the sccs were completely missing in some nkccldeficient mice nkccl mrna was expressed in both the human macula and crista ampullaris and its protein was expressed mainly in the transitional and dark cell areas of the human crista ampullaris