Hair Cell Regeneration In The Mouse Embryonic Cochlea Damaged With Irradiation

Since Lefcbvre(1993) has reported that the regeneration of hair cell is possible in the young mouse cochlea damaged with neomycin. It has caugt the full attention of both clinician and researcher, and more work in this field has been studying recently. In this study, light microscopy (LM), scanning electron microscopy (SEM),transmission electron microscopy (TEM), bromodeoxyuridine (BrdU)and EGF-R immunohistocytochemical method, EGF-R mRNA in situ hybridization,and image analytical technique were used to investigate the hair cell regeneration and its mechanism in fetal mouse cochlea irradiated with 2Gy of ⁶⁰Co gamma ray at the 16th gestational day. The results showed as following1.Hair cell regeneration of the mouse embryonic cochlea damaged with irradiation (1)SEM findingsUnder SEM, regenerative hair cells, polyhedral cells, abnormal hair cells and hair cell loss were found and mingled among the normal hair cells in the damaged area in the newborn mouse cochlea. The characteristic features of these cell were: the regenerative cells showed that their surface area were varied in size, and there were few or no microvillia, and the electron density of their cuticle plate was lower than that in normal .But the density of stereocilli bundle was higher than that in normal and relatively immature. Number of regenerative hair cell was much lower than that in avian; Polyhedral cell showed that there was a kinocilium on it's surface; Abnormal hair cells showed that there were malformed stereocillia bundle on their surface; Area of hair cell loss was instead of supporting cell. All the above findings was not found in the normal control group.