The vas deferens, also known as the ductus deferens, is the key structure responsible for transporting sperm from the epididymis to the ejaculatory duct. Located in the scrotum, the epididymis arches over the lateral side of the testis. The vas deferens extends from the epididymis, traversing through the pelvic cavity, arching over the posterior side of the bladder, and ultimately connecting to the ejaculatory duct.

It is important to differentiate the vas deferens from other structures involved in the male reproductive system. For instance, seminal glands, which are situated on the posterior surface of the bladder, do not transport sperm; instead, they produce seminal fluid that contributes to semen. Additionally, straight tubules within the testes are responsible for the initial transport of sperm before they reach the epididymis. Lastly, the urethra serves as the passage for sperm after it has been transported through the ejaculatory duct, leading to ejaculation.

In summary, the vas deferens plays a crucial role in the male reproductive system by facilitating the movement of sperm from the epididymis to the ejaculatory duct, ensuring the proper transport of sperm during ejaculation.