The ability of sperm cells to move along the ductus deferens is due to ________.

• A. cilia lining the ductus deferens
• B. osmosis of fluids
• C. active flagellar movement of sperm
• D. peristaltic contractions of smooth muscle

Answer: (D)

Verified step by step guidance

1. Understand the anatomy and function of the ductus deferens: The ductus deferens (also called the vas deferens) is a muscular tube that transports sperm from the epididymis to the ejaculatory ducts during ejaculation.
2. Recognize the role of smooth muscle in the ductus deferens: The walls of the ductus deferens are lined with smooth muscle, which is capable of contracting rhythmically.
3. Define peristalsis: Peristalsis refers to the wave-like contractions of smooth muscle that propel substances through a tubular structure, such as food through the digestive tract or sperm through the ductus deferens.
4. Eliminate incorrect options: Cilia are not present in the ductus deferens, so they cannot contribute to sperm movement. Osmosis is a passive process involving water movement and does not apply here. Active flagellar movement of sperm occurs in the sperm itself but is not the primary mechanism for movement along the ductus deferens.
5. Conclude that the correct mechanism is peristaltic contractions of smooth muscle, which propel sperm along the ductus deferens toward the ejaculatory ducts.