| It is now known that birds, unlike mammals, have the ability to regenerate hair cells after injury or trauma. However studies have shown that after regeneration stereocilia bundles are not always correctly polarized for maximum sensitivity. During normal development the placement of the kinocilium directs the polarity of the stereocilia bundle. This study was conducted to determine whether the presence of kinocilia in regenerating hair cells results in stereocilia bundles with polarity more similar to controls, normal hair cells, than those regenerating hair cells without kinocilia. Methods: Thirty-two white leghorn chicks, injected with a single high-dose of gentamicin, were divided into 6 experimental groups and one control. Tissue was prepared for Scanning Electron Microscopic (SEM) analysis of stereocilia bundle orientation and presence of kinocilium after hair cell regeneration. Orientation was measured using the NIH image shareware verse 1.3 program. Results: No significant difference was found in the polarity of cells with and without kinocilia. However, a trend was seen for the average bundle orientation to rotate toward the base across post injection days. Based on these finding the presence or absence of kinocilia does not appear to have an effect on hair cell bundle polarity. Additional research is needed to further investigate whether the kinocilium plays a role in guiding hair cell bundle polarity during regeneration. |
