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KMID : 0376219850220010039
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Chonnam Medical Journal
1985 Volume.22 No. 1 p.39 ~ p.57
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Electron Microscopic Study on the Development of the Skeletal Muscle in the Human Fetus
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Abstract
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The ultrastructural differentiation of the skeletal muscle was investigated in the posterior calf muscles of human fetuses ranging from 11 to 23 weeks of gestational age. And the following results were obtained.
The muscle cells encountered in specimens from 11 to 13 weeks old fetuses were presumptive myoblast, myoblast, and myotube. Fusion of presumptive myoblast (or satellite cell) to myotube or myoblast was often noted. The formation of myofilaments and the sarcomas was started in the myoblast. Myofilament synthesis occurred primarily in the cell periphery where thin filaments appeared to align themselves in relation to Z body and the thick filaments appeared in close association with free ribosome.
As the gestational age was proceeded(20 to 23 weeks), myogenesis was significantly advanced. Primitive muscle cells at this period of gestation were mainly in the forms of myotube and Myofibers to which satellite cells were still fused. Myofibers showed well established myofibrils with many sarcomas especially in the central portion of the cells and had peripherally located nuclei, already formed triads, and increased glycogen particles. At about 23 weeks of gestation, Myofibers were often noted to have wavy or zigzag cell outlines and shorter sarcomas.
These results indicate that the sequence of myogenesis of the posterior calf muscle in human is similar to that of the others reported previously, and myofiber of the second trimester were contractile. And formations of the myofilaments and triads were discussed in relation to the structures present in the primitive muscle cells.
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