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Title: The role of cilia in inner ear development and otolith formation in the zebrafish otic vesicle
Author: Stooke-Vaughan, Georgina A.
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2013
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The inner ear is the vertebrate organ of hearing and balance. The ear structures required for vestibular function are well conserved across vertebrates. Here the zebrafish is used as a model of inner ear development, with a focus on the role of cilia in this process. Otoliths are biomineralised structures required for the sensation of gravity, linear acceleration and sound in the zebrafish ear. Otolith precursor particles, initially distributed throughout the otic vesicle lumen, become tethered to the tips of hair cell kinocilia at the otic vesicle poles, forming two otoliths. I have used high-speed videomicroscopy to investigate the role of hair cells, cilia and ciliary motility in otolith formation. I provide a careful description of the distribution of motile and non-motile cilia in the wild-type otic vesicle. I find that hair cells are essential for the tethering of otoliths within the otic vesicle. Absent cilia or defective ciliary motility lead to the formation of defective otoliths; this suggests that normally cilia help the process of otolith formation. I also show that embryonic movement plays a minor role in the formation of normal otoliths. After 1 day postfertilisation motile cilia within the otic vesicle disappear. Non-motile cilia remain and have a role in relaying developmental signals. Zebrafish otic vesicles developing in the absence of cilia show defects in morphogenesis associated with an incomplete repression of the hedgehog signalling pathway. Hair cells are capable of differentiating and polarising at both cellular and tissue level in the absence of cilia or ciliary motility. However, a decrease in hair cell number is seen in zebrafish mutants with cilia defects. This work increases our understanding of the mechanistic and signalling functions of cilia in development of the zebrafish ear. Some aspects of otolith formation in the zebrafish embryo are also clarified.
Supervisor: Whitfield, Tanya T. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available