What are Bulbourethral Glands?

(Source: Public Domain)

​Also known as Cowper's glands (named for English anatomist William Cowper), the bulbourethral glands are two small glands in the reproductive system of male humans, and many male mammals, that produce and secrete a pre-ejaculate fluid called Cowper's fluid, known colloquially as “pre-cum”.

This fluid is secreted during sexual arousal in order to prepare the man’s urethra for the passage of sperm. The urethra has high levels of acidity, so the fluid from the bulbourethral glands help protect the sperm by creating a more neutral environment in the urethra.

Bulbourethral glands are about the size of a pea in human males, and are found at the back and side of the urethra at the base of the penis. They create and secrete about a teaspoon (~4 milliliters) of fluid during sexual arousal.

It was initially believed that this pre-ejaculatory fluid could contain small amounts of sperm, and therefore potentially cause a pregnancy. However, further studies indicated that this is not the case: the sperm source was rather a leak from the testicles into the vas deferens, rather than from the bulbourethral gland itself.

​The Bulbourethral glands in males are similar to the Bartholin's glands in females. These pea-sized glands were named after the physician, mathematician, and theologian Thomas Bartholin, and are located slightly to the back and left and right of the opening of the vagina. They secrete fluid to lubricate the vagina.

Nuts & Bolts: ​What are Bulbourethral Glands?

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Key terms:

Ejaculate - eject semen from the body at the moment of sexual climax.

Gland - an organ in the human or animal body which secretes particular chemical substances for use in the body or for discharge into the surroundings.

Sperm - the male reproductive fluid.

Urethra - the duct by which urine is conveyed out of the body from the bladder, and which in male vertebrates also conveys semen.

Vagina - the muscular tube leading from the external genitals to the cervix of the uterus in women and most female mammals.

​Vas Deferens - the duct which conveys sperm from the testicle to the urethra.

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Sources/References:

Mark McEntee (December 2, 2012). Reproductive Pathology of Domestic Mammals. Elsevier Science. p. 333. ISBN 978-0-323-13804-8. Retrieved August 20, 2013.

"What is pre-ejaculatory fluid (also known as pre-cum), and can it cause pregnancy?". International Planned Parenthood Federation. 13 February 2019. Retrieved 21 July 2019.

Jeffrey H. Schwartz (1988). Orang-utan Biology. Oxford University Press. p. 92. ISBN 978-0-19-504371-6. Retrieved August 20, 2013.

Killick, S. R; Leary, C; Trussell, J; Guthrie, K. A (2010). "Sperm content of pre-ejaculatory fluid". Human Fertility. 14 (1): 48–52.

​Zukerman, Z; Weiss, D. B; Orvieto, R (2003). "Short Communication: Does Preejaculatory Penile Secretion Originating from Cowper's Gland Contain Sperm?". Journal of Assisted Reproduction and Genetics. 20 (4): 157–159.

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