title: The early events in the healing of laser-produced tympanic membrane perforation.
abstract: CONCLUSIONS
  An immense keratinocyte activity with high cell turnover produced keratin that was delivered to span the perforation. The perforation size did not define the time to closure.
  
  
  OBJECTIVE
  Most tympanic membrane perforations heal spontaneously, whereas a fraction remains patent. A simple, nonsurgical cure for chronic perforations is required. Better understanding of the healing processes might enable the development of a simple medical cure. Therefore the structural events of the healing process were investigated, as well as its dynamics, by comparing perforation size with time to closure.
  
  
  METHODS
  Twenty-four Sprague-Dawley rats were myringotomized with a KTP laser. Different perforation sizes were produced. The 'early closing picture' was assessed with otomicroscopy and light and transmission electron microscopy at between 1 h and 2 weeks after myringotomy and perforation size was monitored until closure.
  
  
  RESULTS
  In all, 40% of the perforations were closed after 8 days and 89% at 12 days. The closing time did not directly correlate with perforation size. A wave of keratinocytes migrates towards the perforation site and disintegrates to form a keratin mass that eventually spans the perforation. A less intense activity is present near the annulus. The origin of the epithelial migration is probably regenerative centers.
authors.affiliation: Department of Otorhinolaryngology, Akershus University Hospital, Sykehusveien 25, Lörenskog, Oslo, Norway. magnusvu@hotmail.com
authors.forename: Magnus
authors.initials: M
authors.lastname: von Unge
authors.forename: Malou
authors.initials: M
authors.lastname: Hultcrantz
mesh_terms: D000818:Animals; D005260:Female; D015603:Keratinocytes / Q000502:physiology*; D053844:Lasers, Solid-State; D046529:Microscopy, Electron, Transmission; D051381:Rats; D017207:Rats, Sprague-Dawley; D014432:Tympanic Membrane / Q000648:ultrastructure; D018058:Tympanic Membrane Perforation / Q000473:pathology*; D014945:Wound Healing