Question

multiple choice question
numerous invaginations of the sarcolemma of a muscle fiber lead down into structures called the

transverse tubules
sarcoplasmic reticulum
thick filaments
mitochondria

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Explanation:

The sarcolemma of muscle fibers has invaginations that form transverse tubules (T - tubules). They help in the rapid transmission of electrical signals for muscle contraction. The sarcoplasmic reticulum stores calcium ions. Thick filaments are part of the myofibrils and mainly consist of myosin. Mitochondria are the power - houses of the cell providing energy.

Answer:

A. transverse tubules