Myofibrils are the contractile fiber and they are made of actin and myosin.
Myofibrils are made of thick myofilaments and thin myofilaments.
Thick myofilaments are made up of myosin whereas thin myofilaments are composed of actin.
The functional unit of muscle is Myofibrils and contraction of muscle occurs due to myofibril, when the filaments actin and myosin interact with each other.
Thus Myofibrils are made primarily of (A) actin and myosin.
