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Pars flaccida perforation in tissue culture: morphological study
L E Stenfors1, E G Olsen, A O Henriksen
1Department of Otolaryngology, University of Tromsö, Norway.
Abstract:
Subtotal pars flaccida perforation was effected in vitro in rat tympanic membranes. The drums were subsequently kept in tissue culture and after various intervals studied by means of light and scanning electron microscopy. No complete covering of the perforation was seen, though a marked thickening and hyperplasia of the outer, keratinizing, squamous epithelium (OE) was evident. The inner, tympanal epithelium (IE) appeared swollen, containing rounded structures in the cytoplasm especially close to the contact area with the OE. Ingrowth of OE onto the tympanal side of the drum was seen particularly in the areas where the IE was sparse and completely lacking. Complete covering of a drum perforation seems to be dependent on the formation of supporting granulation tissue, probably resulting from an inflammatory reaction in the healing area.
Insights
This study found that rat eardrum perforations in vitro did not fully heal. Outer squamous epithelium thickened, but complete closure required granulation tissue formation.
Area of Science:
- Otolaryngology
- Tissue Engineering
- Cell Biology
Background:
- Subtotal pars flaccida perforations in tympanic membranes are a common clinical issue.
- Understanding the in vitro healing mechanisms of eardrum perforations is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the in vitro healing process of subtotal pars flaccida perforations in rat tympanic membranes.
- To analyze the cellular and tissue responses following perforation and their impact on closure.
Main Methods:
- Subtotal pars flaccida perforations were created in rat tympanic membranes in vitro.
- Tympanic membranes were maintained in tissue culture for varying intervals.
- Light and scanning electron microscopy were used to examine the perforation sites.
Main Results:
- No complete closure of the perforation was observed in any sample.
- Significant thickening and hyperplasia of the outer, keratinizing, squamous epithelium (OE) were evident.
- The inner tympanal epithelium (IE) showed swelling and cytoplasmic inclusions, with OE ingrowth observed where IE was sparse.
Conclusions:
- Complete healing of tympanic membrane perforations in vitro is not achieved solely by epithelial regeneration.
- The ingrowth of outer squamous epithelium suggests a potential role in attempting to cover the defect.
- Formation of granulation tissue, likely from an inflammatory response, appears essential for supporting complete perforation closure.