The seminal vesicles are a pair of glands found in the male pelvis that produce many of the constituent ingredients of semen. They are located behind the bladder but in front of the rectum. The muscular tissue of the seminal vesicles contracts to move seminal fluid and sperm into the urethra and out through the penis. The fluids that develop in the seminal vesicles make up an estimated 50% to 80% of semen’s volume. The substances in these fluids are designed to help sperm stay alive once they enter the vagina. The fluids carry:

• Fructose, which provides energy for sperm.
• Prostaglandins, which keep the vagina from seeing sperm as an invader.
• Alkaline fluid, which helps keep the sperm alive in the vagina, which is acidic.
• Clotting factors, which also help to keep sperm alive longer.

The seminal vesicles work together with other parts of the reproductive system, such as the vas deferens and its ampulla, to push out ejaculate into and from the penis. The secretions of the seminal vesicles have a key role in the normal functioning of semen, making up 70% of its total volume. The fluid produced in the seminal vesicles provides an environment that’s very important for the proper functioning and survival of sperm.