Semen is produced by adding fluids to sperm cells as they pass along the reproductive ducts. The sperm pathway begins in the seminiferous tubules. Sperm then pass through the straight tubules, rete testis, efferent ducts, and ductus epididymis within the testis. The vas deferens then moves sperm from the epididymis to the ejaculatory duct. Within this region, sperm mature and are stored. If not ejaculated, the sperm are reabsorbed.
The ejaculatory duct is the site of union of the seminal vesicle and vas deferens. Seminal vesicles and the prostate gland produce most of the fluid of semen. They contribute slightly alkaline buffers, which neutralize the acidity of the male urinary tract and are available to neutralize the acids of the vaginal tract. Fructose provides an energy supply for aerobic metabolism in sperm. Prostaglandins increase sperm motility. The prostate specific antigen (PSA) is secreted by the prostate gland. It liquifies the semen.
Near the entrance to the penis are bulbourethral (Cowper’s) glands that produce a lubricating mucus. They become active during sexual arousal. The urethra itself has three divisions: prostatic passes through the prostate gland, membranous is a short connection to the penis, and spongy (penile), within the penis itself.
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