How seminal vesicle secretions aid sperm motility?

The seminal vesicles are two small glands located behind the bladder in males. They produce a fluid that makes up about 60–70% of the total semen volume, and this fluid plays a vital role in helping sperm move efficiently and survive after ejaculation.

The main way seminal vesicle secretions aid sperm motility is by providing the right environment, nutrients, and protection for sperm cells. Here’s how it works:

1. Provides Energy for Movement

Seminal vesicle fluid is rich in fructose, a type of sugar that acts as the main energy source for sperm. Once sperm leave the testes, they depend on fructose to power their tail movement, which helps them swim toward the egg in the female reproductive tract. Without enough fructose, sperm would lose energy and stop moving effectively.

2. Maintains a Favorable pH

The fluid is slightly alkaline, which helps neutralize the acidic environment of the vagina. This prevents sperm damage and keeps them active for longer. The correct pH balance allows the sperm’s tail (flagellum) to beat strongly, improving forward movement.

3. Supports Liquefaction and Free Movement

Seminal vesicle secretions contain proteins and enzymes that help semen liquefy after ejaculation. This makes it easier for sperm to break free from the thick semen and move through the cervix and uterus.

4. Protects Sperm from Damage

The fluid also contains prostaglandins, which may help sperm penetrate cervical mucus and increase the chances of fertilization. Other compounds, such as citric acid and amino acids, protect sperm membranes and prevent oxidative damage.