What are satellite cells?
What is their function?
Quiescent myoblasts beneath the basal lamina.
They're responsible for myofiber regeneration s/p trauma/disease.
What are myotubes?
Fusion of myoblasts, having multiple centrally placed nuclei.
Maturation leads to peripheral migration of nuclei (myofibers).
What are the different myofiber types?
What is the usual composition of myofiber types by birth?
40% Type I
>55% is abnl
Type I predominence
60% Type II
< 10% Type IIc
Which ATPase stains Type IIc myofibers?
ATPase, pH 4.3
Describe the size comparision between Type I vs. Type II fibers as the fetus grows
Wohlfart A and B
Type I starts off smaller than type II
Type I myofibers grow, become = in size by 3 mo
Surpases Type II by puberty
Persistent of small or hypotrophic Type I fibers ==> non-progressive hypotonia,