Final answer:
The pampiniform plexus runs along the testicular artery in the spermatic cord and serves as a heat exchanger for blood flowing to the scrotum, aiding in the maintenance of an optimal temperature for sperm health.
Step-by-step explanation:
The structure that runs along the testicular artery and serves as a means of heat exchange for blood flowing in and out of the scrotum is the pampiniform plexus. The pampiniform plexus is a network of many small veins found in the human male spermatic cord. This structure is crucial because it helps to keep the temperature in the scrotum optimal for sperm production and survival by cooling the arterial blood before it enters the testes. The vas deferens, epididymis, and seminal vesicles do not serve this heat exchange function; instead, the vas deferens carries sperm from the epididymis to the ejaculatory duct, the epididymis stores and matures sperm, and the seminal vesicles produce seminal fluid that mixes with sperm to form semen.