[Characteristics of auditory brainstem responses and the development of the bundles of inner and outer hair cell of newborn mice].
OBJECTIVE
To investigate the characteristics of the ABR and discuss the development of the bundles of inner and outer hair cell.


METHODS
Testing the ABR of newborn mice, the response threshold of ABR, latency of wave I were examined. Using scanning electron microscopy, the development of the bundles of inner and outer hair cell of postnatal mice were studied.


RESULTS
(1) The average response threshold of ABR was (57.5 +/- 2) dB of 15-day-old mice. The average response threshold of ABR was (37.5 +/- 1) dB of 17-day-old, 21-day-old and 28-day-old mice. There was no difference in wave form. (2) The latencies of wave I of ABR differed significantly (P < 0.05) in 15-day-old mice and 17-day-old mice, 21-day-old mice and 28-day-old mice. The latencies of wave I of ABR didn't differ significantly (P > 0.05) in 17-day-old mice and 21-day-old mice and 28-day-old mice. (3) The development of the bundles is interpreted as a five-step process.


CONCLUSIONS
The stable ABR appeared at the mice of 17 days. The response threshold goes down gradually. The latency of wave I becomes shorter and shorter. The bundles of inner and outer hair cell of newborn 17-day-old mice get maturity.
Li
Cai
C
Department of Otolaryngology, Affiliated Eye Ear Nose Throat Hospital, Fudan University, Shanghai 200031.
Wu
Liwen
L
Chi
Fanglu
F
D000818:Animals; D000831:Animals, Newborn; D016057:Evoked Potentials, Auditory, Brain Stem; D006199:Hair Cells, Auditory, Inner / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D018072:Hair Cells, Auditory, Outer / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D051379:Mice; D008855:Microscopy, Electron, Scanning; D011930:Reaction Time