Pattern of Pax7 expression during myogenesis in the posthatch chicken establishes a model for satellite cell differentiation and renewal

Orna Halevy, Yogev Piestun, Mohammed Z. Allouh, Benjamin W.C. Rosser, Yuval Rinkevich, Ram Reshef, Israel Rozenboim, Monika Wleklinski-Lee, Zipora Yablonka-Reuveni

Research output: Contribution to journalArticlepeer-review

265 Citations (Scopus)


The paired-box transcription factor Pax7 plays a critical role in the specification of satellite cells in mouse skeletal muscle. In the present study, the position and number of Pax7-expressing cells found in muscles of growing and adult chickens confirm the presence of this protein in avian satellite cells. The expression pattern of Pax7 protein, along with the muscle regulatory proteins MyoD and myogenin, was additionally elucidated in myogenic cultures and in whole muscle from posthatch chickens. In cultures progressing from proliferation to differentiation, the expression of Pax7 in MyoD+ cells declined as the cells began expressing myogenin, suggesting Pax7 as an early marker for proliferating myoblasts. At all time points, some Pax7+ cells were negative for MyoD, resembling the reserve cell phenotype. Clonal analysis of muscle cell preparations demonstrated that single progenitors can give rise to both differentiating and reserve cells. In muscle tissues, Pax7 protein expression was the strongest by 1 day posthatch, declining on days 3 and 6 to a similar level. In contrast, myogenin expression peaked on day 3 and then dramatically declined. This finding was accompanied by a robust growth in fiber diameter between day 3 and 6. The distinctions in Pax7 and myogenin expression patterns, both in culture and in vivo, indicate that while some of the myoblasts differentiate and fuse into myofibers during early stages of posthatch growth, others retain their reserve cell capacity.

Original languageEnglish
Pages (from-to)489-502
Number of pages14
JournalDevelopmental Dynamics
Issue number3
Publication statusPublished - Nov 2004
Externally publishedYes


  • MyoD
  • Myofiber diameter
  • Myogenin
  • Pax7
  • Pectoralis
  • Posthatch muscle growth
  • Skeletal muscle satellite cells

ASJC Scopus subject areas

  • Developmental Biology


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