The collagen structure of the tympanic membrane: collagen types I, II, and III in the healthy tympanic membrane, during healing of a perforation, and during infection.
OBJECTIVE
To analyze the distribution of 3 collagen types in healthy tympanic membranes, during healing of a perforation, and during infection.


METHODS
Immunohistochemical study of collagen types I, II, and III in the tympanic membranes of healthy rats as well as during healing of a perforation and in the presence of infection with Streptococcus pneumoniae at various time points.


METHODS
Laboratory research center at a university hospital.


RESULTS
Type II collagen was a main constituent of the lamina propria of the pars tensa, whereas type I collagen was found mainly in the pars flaccida. Collagen types I and III were found at the insertion to the malleus handle and in the loose connective tissue surrounding the main collagen layer of the pars tensa. After myringotomy, collagen types I and III were found at the perforation border and around dilated blood vessels early in the healing phase. During infection, the collagen layer was thickened and stained strongly for type II collagen. Collagen types I and III were found in the edematous connective tissue around the main collagen layer and around dilated blood vessels. Three months after perforation or infection, all 3 collagens were present in the lamina propria of the tympanic membrane. Extensive amounts of all 3 collagen types were present in the scar tissue in the tympanic membranes of rats that had undergone myringotomy during the presence of acute otitis media.


CONCLUSIONS
The lamina propria of the pars tensa is mainly made up of type II collagen, whereas type I collagen is found in the pars flaccida. Thus the fibrous structure of the pars tensa and flaccida is composed of diverse collagen types, which reflects the different physiological properties of these tissues. Collagen types I and III are present in the acute healing phase after myringotomy and infection, and the collagen content of the tympanic membrane is modified during the inflammatory and healing process.
Department of Otorhinolaryngology, Umeå University Hospital, Umeå, Sweden. Karin.Stenfeldt@telia.com
Karin
K
Stenfeldt
Cathrine
C
Johansson
Sten
S
Hellström
D000818:Animals; D024042:Collagen Type I / Q000032:analysis*; D024043:Collagen Type II / Q000032:analysis*; D024061:Collagen Type III / Q000032:analysis*; D003238:Connective Tissue / Q000737:chemistry; D004427:Ear Diseases / Q000378:metabolism; D004487:Edema / Q000378:metabolism; D007150:Immunohistochemistry; D007239:Infections / Q000378:metabolism*; D007249:Inflammation / Q000378:metabolism; D008297:Male; D009092:Mucous Membrane / Q000737:chemistry; D011008:Pneumococcal Infections / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014432:Tympanic Membrane / Q000737:chemistry* / Q000601:surgery; D018058:Tympanic Membrane Perforation / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology*
D024042:Collagen Type I; D024043:Collagen Type II; D024061:Collagen Type III