Comparison of two Methods for the Modeling of Tympanosclerosis in Rat / 听力学及言语疾病杂志

ABSTRACT

Objective To establish a rat model of tympanosclerosis(TS) by myringotomy and inoculation of streptococcus pneummoniae, and to observe the morphological change in the tympanic membrane (TM) and middle ear mucous.Methods Forty Sprague-Dawley rats were randomly divided into two groups (n=20/group) and then ten in each group were chosen to serve as the control and the other ten were set up for the TS model.Group A (myringotomy) myringotomy was performed on the bilateral TMs of all rats except the control group.Group B (bacterial inoculation) streptococcus pneumoniae was inoculated into the bilateral middle ear cavity of all rats except the control group.The condition of the TMs and the middle ears in the two groups were respectively examined at 2 weeks after myringotomy and at the five time points (1 week, 2 weeks, 4 weeks, 6 weeks, and 8 weeks) after bacterial inoculation.Then the rats were decapitated and the morphological changes were observed by hematoxylin and eosin staining.Results One rat in group B died two weeks after the inoculation.In the two experimental groups, the calcifications were observed in 70%of the TMs (14/20) in group A and in 33.33%of the TMs (6/18) at 8 weeks in group B.At the same time, the inflammatory infiltration and hyaline degeneration markedly appeared in the tympanic membrane and middle ear mucous membrane.In the two control groups, neither morphological changes nor calcifications occurred.Conclusion The current study indicated that the animal model of TS was successfully accomplished by myringotomy and inoculation of streptococcus pneummoniae, and their morphological changes were basically consistent.However, the method of myringotomy is easier to use and can obtain a higher modeling rate in a relatively short time.