Final answer:
Slow-twitch muscle fibers have a large number of capillaries, while fast-twitch muscle fibers have fewer capillaries.
Step-by-step explanation:
Skeletal muscle fibers can be divided into two types: slow-twitch (or type I) muscle fibers and fast-twitch (or type II) muscle fibers. Slow-twitch fibers, also known as Type I fibers, are dense with capillaries and rich in mitochondria and myoglobin. They can carry more oxygen and sustain aerobic activity. On the other hand, fast-twitch fibers, also known as Type II fibers, contain fewer capillaries and mitochondria and less myoglobin. They can contract rapidly and powerfully but fatigue quickly.