GENERAL HISTOLOGY

Detailed explanation-1: -A single muscle fiber contains hundreds to thousands of rod-like myofibrils that run parallel to its length (Figure 9.2b). The myofibrils, each 1–2 m in diameter, are so densely packed in the fiber that mitochondria and other organelles appear to be squeezed between them.

Detailed explanation-2: -Myofibrils run the entire length of the muscle fiber, and because they are only approximately 1.2 µm in diameter, hundreds to thousands can be found inside one muscle fiber.

Detailed explanation-3: -Each bundle of muscle fiber is called a fasciculus and is surrounded by a layer of connective tissue called the perimysium. Within the fasciculus, each individual muscle cell, called a muscle fiber, is surrounded by connective tissue called the endomysium.

Detailed explanation-4: -A muscle fiber is composed of many myofibrils, which contain sarcomeres with light and dark regions that give the cell its striated appearance.