First, sperm cells are produced in the small seminiferous tubules of the testes. These oval-shaped glands are protected by a sac called the scrotum. After the sperm cells are produced, they are stored in a large coiled tube on the outer surface of each testicle called the epididymis. From this tube, the sperm go into a larger tube called the vas deferens, which eventually carries them to the external male reproductive organ, the penis. Along the way, sperm is nourished by a sugary fluid from the seminal vesicle.