title: Tympanic membrane changes in experimental acute otitis media and myringotomy.
abstract: OBJECTIVE
  The present experimental study explored pathomorphological changes and calcium depositions in the tympanic membrane during experimental acute otitis media caused by nontypeable Haemophilus influenzae in myringotomized and nonmyringotomized ears.
  
  
  METHODS
  A rat model of experimental acute otitis media caused by nontypeable Haemophilus influenzae was employed. Sixteen Sprague-Dawley rats were used. Four days following middle ear inoculation, a bilateral myringotomy was performed in six randomly selected animals. Another group of 10 animals was inoculated only. On days 4, 7, 14, and 28 after inoculation, two animals from each group were sacrificed. The temporal bones were removed and the tympanic membranes were dissected, followed by paraffin embedding. Adjacent sections were stained with PAS-alcian blue for basic histopathological observations and by von Kossa method for determination of calcium phosphate depositions.
  
  
  RESULTS
  Particularly intense invasion of polymorphonuclear neutrophil leukocytes was seen on day 4 after inoculation. The highest infiltration of macrophages was observed on day 7. The peak number of lymphocytes was seen on day 14. No difference occurred in the number of polymorphonuclear leukocytes in myringotomized and nonmyringotomized tympanic membranes. The infiltration with lymphocytes and activated macrophages in all parts of the myringotomized tympanic membranes was statistically significantly higher than in the nonmyringotomized animals. The total amount of interstitial calcium phosphate depositions during days 7, 14, and 28 of study was statistically higher in the sections of pars tensa from myringotomized membranes compared to the nonmyringotomized membranes.
  
  
  CONCLUSIONS
  Nontypeable Haemophilus influenzae-induced acute otitis media and myringotomy provoke more extensive inflammatory reaction with microcalcification in the tympanic membranes.
authors.affiliation: Department of Otorhinolaryngology, Kaunas University of Medicine, Eiveniu 2, 50009 Kaunas, Lithuania. giedre.alzbutiene@gmail.com
authors.forename: Giedre
authors.initials: G
authors.lastname: Alzbutiene
authors.forename: Ann
authors.initials: A
authors.lastname: Hermansson
authors.forename: Per
authors.initials: P
authors.lastname: Cayè-Thomasen
authors.forename: Vytenis
authors.initials: V
authors.lastname: Kinduris
mesh_terms: D000208:Acute Disease; D000818:Animals; D002114:Calcinosis / Q000473:pathology; D002130:Calcium Phosphates / Q000378:metabolism; D004396:Coloring Agents; D003627:Data Interpretation, Statistical; D004195:Disease Models, Animal; D006192:Haemophilus Infections / Q000150:complications; D006193:Haemophilus influenzae; D007249:Inflammation / Q000473:pathology; D008264:Macrophages; D008297:Male; D009504:Neutrophils; D010033:Otitis Media / Q000209:etiology / Q000382:microbiology / Q000473:pathology* / Q000601:surgery*; D010034:Otitis Media with Effusion / Q000209:etiology / Q000473:pathology / Q000601:surgery; D016612:Paraffin Embedding; D051381:Rats; D017207:Rats, Sprague-Dawley; D012598:Sclerosis / Q000473:pathology; D013997:Time Factors; D014432:Tympanic Membrane / Q000378:metabolism / Q000473:pathology* / Q000601:surgery*
chemical_list: D002130:Calcium Phosphates; D004396:Coloring Agents; C020243:calcium phosphate