Continuous myonuclear addition to single extraocular myofibers in uninjured adult rabbits

Linda K. McLoon, Jonathan D. Wirtschafter

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Extraocular muscles (EOM) are unique among mammalian skeletal muscles in that they normally express molecules associated with muscle development and regeneration. In this study we show that satellite cells of EOM, unlike those of other skeletal muscles, continually divide in the normal, uninjured adult. Adult EOM contained activated satellite cells positive for the myogenic regulatory factor MyoD. EOM satellite cells did not require a prolonged activation period prior to onset of cell division and differentiation in vitro. EOM satellite cells incorporated bromodeoxyuridine (brdU), a marker for cell division, and with longer postlabeling survival, brdU-labeled nuclei populated EOM myofibers. This was not seen with leg muscle. These findings suggest the possibility that continual division of satellite cells and fusion of their daughter myocytes with existing adult EOM myofibers contribute to the unique sparing or susceptibility of EOM to certain muscle diseases.

Original languageEnglish (US)
Pages (from-to)348-358
Number of pages11
JournalMuscle and Nerve
Issue number3
StatePublished - Mar 19 2002


  • Extraocular muscles
  • Mitosis
  • Myofibers
  • Satellite cells


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