The repair process of neomycin induced cochlear damage in the postnatal developing rat was investigated in the present study. The results showed that electron dense atypical cells with a cluster of microvilli on their apical surface, resembling early stage of embryonic hair cell, were observed in the former hair cell region. The striking finding was that microglia-like cells appeared and replaced OHCs in the injured auditory sensory epithelium. Using Brdu immunohistry, cell prolifera-tion was found in the area of inner and outer spiral sulcus but not in the hair cells and supporting cells. It is proposed that microglia-like cells play a role in eliminating waste products from the organ of Corti and may participate in direct structural repair. NeuroReport 11: 1389-1393

The apoplosls occurring in the postnatal developing spiral ganglion cells (SGCs) and Ihe concomitant change in Bax-prolein immunmeuctlvity were investigated in rats at postnatal days (P) I, 3, 5, 7, l0 and 14, and also in adull rats In P5 and P7 rals, some neurons showed structural features of poptosis, includlng cell shrinkage, condensed chromatin around the margin of the nucleus and phagocytosis of apoptotic bodies by satellite coils. The percentage of Bax-protein- positive neurons ill the spiral ganglion was significantly higher in PI, P3, PS, lind P7 rat5 compared with adult rats Our resulls conflm the oecurrace of neuronad cell apoptosis in the splmal ganglion at the end of the first ostllatal week, and demonstrate the trallsJent chalge in Bax-plotein immunorcactlvity prior Io neuronal cell apoplosJs Thus, we speculate that the Iransient change in Bax protein could be involved in neuronal cell apoptosis of the postnatal developing SGCs of rats.

To investigate regeneration of the distal facial nerve following nerve grafting within the tympanic segment with geniculate ganglion preservation of dissection.

Fr the efficacy and saftey of the surgical manipulation in stapedotomy for otosclerosis, the author did such surgery using CO2 lair in 44 cases. postperative follow up (3-12 months) reveals that hearing mean gain is 31+75:8.2 dB and air-bone conduction gap is within 11, 25:6.6 dB. There is no significant change at 4000 Hz. The advantages of CO2 laser tenlque are summarized as follows: convenience for cutting posterior crus, less lime eonuming for penetration on thick footpkate or removal of occlusive slerotic plaque within the oval window niche, avoidance of footptate flatlng with slight fixation of fooplate, and rapid coagulation of residual stzpedia artery as well as no instrumental difficulties at some narrow spaces. Our results state that CO2 lair creates essntial improvement in the development of the stapedotomy in otosclerosis.