Rat model of chronic tympanic membrane perforation : A longitudinal histological evaluation of underlying mechanisms

• Objective: To evaluate histologically the progressive development and underlying mechanisms of chronic tympanic membrane perforation (TMP) in a rat model using a two-weeks ventilation tube (VT) treatment combined with topical application of mitomycin Cidexamethasone (VT-MID), compared with normal tympanic membrane and acute TMPs. Methods: Fifty male Sprague-Dawley rats were divided into three experimental groups: a normal control group (n = 5), an acute TMP group (n = 5) (i.e. 3 days post-myringotomy) and a VT-M/D group (n = 40). The TMs were regularly assessed by otoscopy. The normal control animals were sacrificed on day 0 and the acute TMP group was sacrificed 3 days post-myringotomy for histological and immunohistochemical evaluations. The VT-M/D group was sacrificed at various time points - 14 and 17 days, 3, 4, 6, 8 and 10 weeks. Results: On longitudinal histological examination, compared with normal TM and acute TMP, the perforation edges at the later time points illustrated thickened stratified squamous epithelium rimming around the edges, significant increase in keratin and collagen deposition, increased macrophage infiltration as well as reduced cellular proliferation. Three phases of TMP healing process were identified the acute healing phase (3-17 days), the transition phase (3-4 weeks) and the chronic phase (6-10 weeks). Conclusion: Based on the histological results of this study, the progressive development of chronic TMPs appeared to be associated with increased epidermal thickening, collagen and keratin deposition, macrophage infiltration and reduced cellular proliferation. After the 3-4 weeks of transition phase, the TMPs seemed to have transformed into a non-healing chronic TMP between 6 and 10 weeks. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Oto-rhino-laryngologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Otorhinolaryngology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Pediatrik (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Pediatrics (hsv//eng)

Nyckelord

Tympanic membrane perforation

Chronic

Animal model

Rat

Ventilation tube

Histology

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)