Final answer:
The spermatic cord is the structure that encases the nerves and vessels and includes the ductus deferens, which transports sperm. The seminal vesicles contribute most of the seminal fluid, vital for sperm function.
Step-by-step explanation:
The covering around the nerves and vessels that encloses the seminal duct is known as the spermatic cord. The spermatic cord bundles together connective tissue, blood vessels, and nerves alongside the ductus deferens (vas deferens), which transports sperm from the epididymis to the ejaculatory duct. Furthermore, the seminal fluid, which contains nutrients and substances necessary for sperm viability and motility, is produced by the seminal vesicles and makes up about 70 percent of semen.