Anatomy and Physiology

Male Reproductive System- Accessory sex glands

Accessory sex gland

Accessory Sex Glands of the male reproductive system transport the sperm cells & secrete most of the liquid portion of semen. These are-

Seminal Vesicles-

-The paired seminal vesicles about 5 cm in length are convoluted pouch-like structures, lying posterior to the base of the urinary bladder, they secrete an alkaline fluid that neutralizes the acidic environment of the male urethra as well as the female reproductive tract.

-These contribute about 60% of the total volume of semen.

-Its secretion contains fructose, is needed for ATP production by sperm, the prostaglandin causes smooth muscle contractions within the female reproductive tract & sperm motility & the clotting proteins, to coagulate semen after ejaculation.


-The prostate is a single, size & shape of a golf ball.

-It is inferior to the urinary bladder and surrounds the prostatic urethra.

-It contributes 25% of the volume of semen, then enters into the prostatic urethra through many prostatic ducts.

-It secretes a milky acidic fluid containing Citric acid which is used by sperm. Proteolytic enzymes, like- prostate-specific antigen, pepsinogen, lysozyme, amylase, and hyaluronidase, these then break down the clotting proteins from the seminal vesicles.

-Seminalplasmin is an antibiotic that can destroy bacteria.

Bulbourethral Glands-

-Also known as Cowper’s glands, these are the paired, about the size of peas.

-They are located inferior to the prostate on either side of the membranous urethra within the deep muscles of the perineum.

-It secretes an alkaline fluid into the urethra that neutralizes acids in the urine & protects the sperm.

-The mucus secreted by them lubricates the end of the penis and the urethra thus decreases the number of sperm damaged during ejaculation.

These all glands contribute a fluid part, seminal fluid, a fluid formed from the seminiferous tubules, seminal vesicles, prostate or the bulbourethral gland. It provides sperm a transportation medium, nutrients, and protection from the acidic environment of the male’s urethra and the female’s vagina. Semen is a mixture of sperm and seminal fluid, with a slightly alkaline pH of 7.2–7.7 (as a larger volume of fluid from the seminal vesicles), prostatic secretion gives semen a milky appearance, and seminal vesicles and bulbourethral secretion give it a sticky consistency. Each ejaculation contributes a volume of 2.5–5 mL, with 50–150 million sperm per mL. After ejaculation, it becomes coagulates within 5 minutes due to the presence of clotting proteins from the seminal vesicles. After 10 to 20 minutes it reliquefies because proteolytic enzymes produced by the prostate break down the clot.

For better understanding, you can watch this video

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