Elastic fiber-mediated enthesis in the human middle ear

Tetsuaki Kawase, Shunichi Shibata, Yukio Katori, Aiji Ohtsuka, Gen Murakami, Mineko Fujimiya

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16 Citations (Scopus)

Abstract

Adaptation to constant vibration (acoustic oscillation) is likely to confer a specific morphology at the bone-tendon and bone-ligament interfaces at the ear ossicles, which therefore represent an exciting target of enthesis research. We histologically examined (i) the bone attachments of the tensor tympani and stapedius muscles and (ii) the annular ligament of the incudostapedial joint obtained from seven elderly donated cadavers. Notably, both aldehyde-fuchsin and elastic-Masson staining demonstrated that the major fibrous component of the entheses was not collagen fibers but mature elastic fibers. The positive controls for elastic fiber staining were the arterial wall elastic laminae included in the temporal bone materials. The elastic fibers were inserted deeply into the type II collagen-poor fibrocartilage covering the ear ossicles. The muscle tendons were composed of an outer thin layer of collagen fibers and an inner thick core of elastic fibers near the malleus or stapes. In the unique elastic fiber-mediated entheses, hyaluronan, versican and fibronectin were expressed strongly along the elastic fibers. The hyaluronan seemed to act as a friction-reducing lubricant for the elastic fibers. Aggrecan was labeled strongly in a disk- or plica-like fibrous mass on the inner side of the elastic fiber-rich ligament, possibly due to compression stress from the ligament. Tenascin-c was not evident in the entheses. The elastic fiber-mediated entheses appeared resistant to tissue destruction in an environment exposed to constant vibration. The morphology was unlikely to be the result of age-related degeneration.

Original languageEnglish
Pages (from-to)331-340
Number of pages10
JournalJournal of Anatomy
Volume221
Issue number4
DOIs
Publication statusPublished - Oct 1 2012

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Keywords

  • Ear ossicles
  • Elastic fibers
  • Enthesis
  • Human anatomy
  • Hyaluronan
  • Stapedius muscle
  • Tensor tympani muscle

ASJC Scopus subject areas

  • Anatomy
  • Ecology, Evolution, Behavior and Systematics
  • Histology
  • Molecular Biology
  • Developmental Biology
  • Cell Biology

Cite this

Kawase, T., Shibata, S., Katori, Y., Ohtsuka, A., Murakami, G., & Fujimiya, M. (2012). Elastic fiber-mediated enthesis in the human middle ear. Journal of Anatomy, 221(4), 331-340. https://doi.org/10.1111/j.1469-7580.2012.01542.x