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Updated: Aug 10, 2026

Fiber Type Identification of Human Skeletal Muscle
Published on: September 22, 2023
Characterization of the giant myofiber in bovine skeletal muscle
Abstract:
Semitendinosus (ST) muscle samples were excised pre- and postrigor from 32 experimental animals (Bos taurus). Four intact and 4 castrate males were exsanguinated when they reached age endpoints of 8, 12, 16, and 20 months. The samples were sectioned, histochemically fiber-typed for SDH and ATPase activity, and examined for giant myofibers. Of the 32 muscles analyzed, only one (8-month intact male) postrigor ST contained a giant myofiber that was hematoxylin and eosin positive, SDH negative, ATPase positive, and 2 X the size of the surrounding fibers. Subsequent studies demonstrated these giant type II white myofibers are an anomaly of muscle contraction and not a distinct fiber type as has been previously reported. This is a first report of giant white or type II myofibers in postrigor bovine skeletal muscle.
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