Final answer:
The tough fibrous capsule that surrounds the testis is called the tunica albuginea. It is a connective tissue layer that covers the testis and helps in the development and protection of sperm.
Step-by-step explanation:
The tough fibrous capsule that surrounds the testis is called the tunica albuginea. It is a tough, white, dense connective tissue layer that covers the testis itself. The tunica albuginea not only covers the outside of the testis, but it also invaginates to form septa that divide the testis into lobules where sperm develop.