Key result
Embryonic myotubes initially express both myomesin and M protein before M protein becomes fiber-type specific.
Findings in chick embryos should not yet change clinical practice; leaves open whether M protein patterns apply to human cardiac or skeletal myogenesis.
The expression of the myosin-associated M band proteins myomesin and M protein in differentiating muscle fibers in the anterior latissimus dorsi (ALD) and posterior latissimus dorsi (PLD) muscles during embryonic chicken development was examined by immunocytochemistry using monoclonal antibodies. Early in the embryonic development of both muscles, both myomesin and M protein are expressed in primary and secondary myotubes. However, beginning at 10 days in ovo, M protein is gradually suppressed first in primary, then in secondary, presumptive slow-tonic type 3 fibers. M protein is transiently suppressed in presumptive fast-twitch type 2 fibers derived from primary myotubes but continuously expressed in those derived from secondary myotubes. Thus, initially all myotubes have a common intrinsic M band composition with respect to myomesin and M protein, whereas at later stages the expression of M protein is fiber-type specific. Intrafusal spindle fibers, which are segregated from extrafusal fibers around 14 days in ovo, have a heterogeneous M band composition atypical of extrafusal fibers.
No takes yet. Share an insight, caveat, or question.
Grove et al. (1988) studied Embryonic chicken development. Expression of myomesin and M protein was evaluated on Expression patterns of myomesin and M protein in differentiating muscle fibers. During embryonic chicken development, myomesin and M protein are initially expressed in all myotubes, but M protein expression later becomes fiber-type specific.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: