Development of primary cilia in the mouse inner ear

The cochlear and vestibular epithelium contain mechanosensory hair cells mediating the detection of hearing and balance respectively. The process of mechanotransduction relies on the deflection of stereocilia. The correct arrangement of all cells in the organ of Corti is mediated by the primary cilium in supporting cells and kinocilium in sensory cells. The cochlear kinocilium degenerates between P8 - P12 while the vestibular kinocilium persists. The development of supporting cell primary cilia was not investigated yet. We performed immunohistochemical staining (IHC) of the mouse cochlea and vestibulum in different ages (P0/1; P8; P12 and P30) using markers for primary cilia function and development including acetylated tubulin, ARL13B and IFT140. The results were analysed using confocal laser scanning microscopy. Additionally, we performed scanning electron microscopy (SEM) at P2, P5 and P80. At P0/1 all IHC markers stain kinocilia and primary cilia of the cochlear and the vestibular epithelium. While all markers provide a positive ciliary staining in the vestibulum for P8, P12 and P30, no ARL13B- or IFT140-positive cochlear primary cilia & kinocilia are visible in P8 or older mice. Beside the known degeneration of cochlear hair cell kinocilia starting from P8 on, the tubulin-staining indicates a similar loss of supporting cell primary cilia in the cochlea between P8 - P12. With SEM we could not detect primary cilia at P2 and p5 but not at p80. We conclude that the primary cilia of cochlear supporting cells in mice degenerate between P8 - P12 together with the hair call kinocilium. This limits the regenerative capacity of the organ of Corti further as the supporting cells as well as sensory cells lose their primary cilia to navigate cell polarity.

Publication History

Article published online:
19 April 2024