The seminal vesicles are located below the bladder and above the prostate gland. An individual seminal vesicle consists of a single coiled tube off of which several pouches branch.
The tube of a seminal vesicle is made up of three different layers:
- moist inner layer of specialized cells that work to produce seminal vesicle fluid
- middle layer of smooth muscle tissue
- outer layer of connective tissue
Part of the seminal vesicles and the vas deferens combine to form the ejaculatory duct, which eventually drains into the prostatic portion of the urethra. During ejaculation, the smooth muscle layer of the seminal vesicles contracts, releasing the seminal vesicle fluid into the ejaculatory duct.
The function of the seminal vesicles is to both produce and store fluid that will eventually become semen. This fluid comprises about 70 percent Trusted Source of the fluid that’s released during ejaculation.
The fluid produced in the seminal vesicles provides an environment that’s very important for the proper functioning and survival of sperm. The main components of this fluid are:
- fructose, a sugar that provides sperm with energy
- alkaline fluid, which helps to neutralize the acidic nature of the male urethra and the female vagina
- proteins like semenogelin, which forms a gel-like protective layer around sperm
- phosphorus and potassium, which help sperm move
- prostaglandins, hormones that have a role in lowering the female immune response to semen