There is a seminal vesicle on both the right and left sides. The seminal vesicles are elongated, pouch-like glands located on the posterior surface of the bladder. They each merge with the ampulla of the right and left ductus deferens to form the right and left ejaculatory ducts.
Figure 1: A labeled illustration of a posterior view of the seminal vesicles, shown with the entire male reproductive system on the left, and in more detail on the right.
At the time of ejaculation, the seminal vesicle secretes an alkaline fluid rich in fructose into the ejaculatory duct. This fluid joins the sperm as part of the semen. Fructose is sugar that can be used by the sperm to produce energy in the form of ATP. The secretion of the seminal vesicle will also help the semen coagulate outside of the male’s body. This temporary clot can help sperm cells move deeper into the female reproductive tract, where fertilization can take place.