Final answer:
Skeletal muscle fibers are multinucleated with striations from the alignment of thick and thin filaments of myosin and actin. They have transversal tubular extensions of the sarcolemma, known as T-tubules. However, they are not continuous from tendon to tendon.
Step-by-step explanation:
The microscopic anatomy of skeletal muscle fibers reveals several true statements including that: muscle fibers are multinucleated, which indicates that they have many nuclei. This occurs because multiple myoblasts fuse together to form a long muscle fiber. Additionally, the cross striations are indeed the result of the lateral alignment of thick and thin filaments of myosin and actin respectively, within the muscle cells or myocytes, giving them the striated appearance. Tubular extensions of the sarcolemma do penetrate the fiber transversely; these are known as T-tubules which run deep into the muscle fiber, allowing electrical impulses to travel quickly and stimulate muscle contraction. However, muscle fibers are not continuous from tendon to tendon; rather, they are anchored to tendons at their ends. Hence, not all of the given statements are correct.