Fig. 5
From: Intracellular Ca2+-handling differs markedly between intact human muscle fibers and myotubes
The ultrastructure differs markedly between human muscle fibers and myotubes. Representative TEM image of the ultrastructure in human intercostal muscle fibers (a, c) and human myotubes (b, d). b Note presence of areas containing rudimentary myofilament structures along with areas that lack even rudimentary myofilament structures in myotubes. c, d Magnification of the areas indicated in a, b, respectively. In human intercostal muscle fibers (c), the characteristic arrangement of myofibrils separated by triads (arrow) at the junction of the A (A) and I bands (I) that are absent in human myotubes (d), where only rudimentary myofilament structures (asterisk) can be seen. Scale bars indicate 1 μm