Each muscle fiber is divided into myofibrils that contain thick (myosin) and thin (actin) myofilaments. The myofilaments give skeletal muscle a characteristic striated, or striped, structure.

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such as the leg muscles used for jumping, have fewer mitochondria but more myofibrils to generate force. In humans, the muscles are to some extent affected by training. The work is published in ...

Next, the team isolated the heart muscle cells (cardiomyocytes) and fibers within the cells (myofibrils) and looked into how these adapted after a big feeding and compared them with those from starved ...