Chicks regenerate hair cells in auditory and vestibular organs after damage, making them a valuable animal model to study the signals controlling hair cell regeneration. This project aims to identify changes in gene expression after hair cell loss in the chick cochlea and vestibular system. The collected data will be comprehensive because it will cover all detectable expressed genes. Subsequent data analysis will focus on establishing a sequence of gene expression changes that we hypothesize will correlate with important steps of the hair cell regeneration process. These steps include the signals that initiate, execute, sustain, and ultimately terminate the regenerative process. Comparison among the different organs and across species through collaborations with other HRP investigators will allow us to draw conclusions about species-specific specialized mechanisms as well as more general processes that control hair cell regeneration.