Meeting Abstract
Thyroid hormone plays an important role in mineralization of the skeleton throughout development and maintenance of mineralization into adulthood. Hypo- and hyperthyroidism lead to lack of mineralization and hypermineralization respectively, both of which can lead to long-term issues such as increased fracture risk and impaired functionality of bones. Indeed, hypothyroidism has been associated with anatomical defects within the middle ear of mammals, although the functional implications of these skeletal abnormalities have not been investigated. Here we use the zebrafish as a model to investigate the role of thyroid hormone in proper mineralization of several cranial features. Middle ear ossicles in mammals are derived from the hyomandibula and quadrate that support the jaws within fishes. In contrast, Weberian ossicles that characterize Ostariophysan fishes (rendering them hearing specialists) are derived from ribs and vertebral elements. Here, we investigate patterns of mineralization in both the hyomandibula and quadrate as well as the tripus, a key Weberian ossicle. These data are used in the development of a model system to evaluate morphological patterns of mineralization in both homologues of mammalian middle ear ossicles as well as ostariophysan Weberian ossicles. Functional hearing tests on these thyroid-disrupted zebrafish will ultimately be performed to determine the specific functional consequences of these improperly mineralized bones. The fact that Weberian ossicles are functionally analogous to the ossicles of the mammalian middle ear will allow us to hypothesize how mineralization defects may affect human hearing.
