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Myringotomized mice develop myringosclerosis in the pars flaccida and not in the pars tensa
C Mattsson1, L Carlsson, S L Marklund
1Department of Otorhinolaryngology, University Hospital of Umea, Sweden.
Abstract:
The development of myringosclerosis has been correlated with increased production of oxygen-derived free radicals. For the present study, we used a null mutant mouse lacking extracellular superoxide dismutase to test the hypothesis that increased production of free radicals can cause the development of myringosclerosis. Null mutant mice and wild-type, control mice were myringotomized and kept in ambient air for 3 weeks. Both groups developed myringosclerosis in the pars flaccida, but not in the pars tensa. The sclerotic lesions were visible in both the light and the electron microscope but not in the otomicroscope. In particular, the localization of the sclerotic deposits was found beneath both the inner and outer epidermal epithelium. No difference concerning the extent or number of sclerotic lesions between the null mutant and the wild-type mice could be distinguished.
Insights
This study investigated if increased free radicals cause myringosclerosis. Results showed no difference in myringosclerosis development between mice with or without extracellular superoxide dismutase, suggesting free radicals may not be the sole cause.
Area of Science:
- Otolaryngology
- Cell Biology
- Biochemistry
Background:
- Myringosclerosis development is linked to elevated oxygen-derived free radicals.
- Extracellular superoxide dismutase (ecSOD) plays a role in neutralizing these radicals.
Purpose of the Study:
- To test the hypothesis that increased free radical production causes myringosclerosis.
- To investigate the role of extracellular superoxide dismutase in myringosclerosis pathogenesis.
Main Methods:
- Myringotomy was performed on null mutant mice lacking ecSOD and wild-type control mice.
- Mice were maintained in ambient air for 3 weeks to observe lesion development.
- Histological analysis using light and electron microscopy was employed to evaluate sclerotic lesions.
Main Results:
- Both null mutant and wild-type mice developed myringosclerosis in the pars flaccida, but not the pars tensa.
- Sclerotic deposits were localized beneath the epidermal epithelium.
- No significant difference in the extent or number of lesions was observed between the two groups.
Conclusions:
- The absence of extracellular superoxide dismutase did not alter the development or severity of myringosclerosis.
- These findings suggest that while free radicals are implicated, they may not be the sole causative factor in myringosclerosis development.