The bulbourethral glands or Cowper's glands (named for English anatomist

William Cowper William Cowper ( ; – 25 April 1800) was an English poet and Anglican hymnwriter. One of the most popular poets of his time, Cowper changed the direction of 18th-century nature poetry by writing of everyday life and scenes of the Engli ...

) are two small exocrine and accessory glands in the reproductive system of many

male mammals A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

. They are homologous to

Bartholin's gland The Bartholin's glands (named after Caspar Bartholin the Younger; also called Bartholin glands or greater vestibular glands) are two pea-sized compound racemose glands, compound alveolar glandsManual of Obstetrics. (3rd ed.). Elsevier. pp. 1-16. . ...

s in females. The bulbourethral glands are responsible for producing a pre-ejaculate fluid called Cowper's fluid (known colloquially as ''pre-cum''), which is secreted during sexual arousal, neutralizing the acidity of the urethra in preparation for the passage of sperm cells. The paired glands are found adjacent to the urethra just below the

prostate The prostate is an male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found in all male mammals. It differs between species anatomically, chemica ...

, seen best by

screening (medicine) In medicine, screening is a strategy used to look for as-yet-unrecognised conditions or risk markers. This testing can be applied to individuals or to a whole population without symptoms or signs of the disease being screened. Screening Public h ...

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

as a tool in preventative healthcare in males. Screening MRI may be performed when there is a positive prostate-specific antigen on basic laboratory tests. Prostate cancer is the second-most common cause of cancer-related mortality in males in the USA. Most species of placental mammals have bulbourethral glands, but they are absent in

Caniformia Caniformia is a suborder within the order Carnivora consisting of "dog-like" carnivorans. They include Canidae, dogs (Wolf, wolves, foxes, etc.), bears, raccoons, and Mustelidae, mustelids. The Pinnipedia (pinniped, seals, walruses and sea lions) ...

and

Cetacea Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively c ...

. They are the only accessory reproductive glands in male

monotremes Monotremes () are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified ...

. Placental mammals usually have one pair of bulbourethral glands, while male marsupials have 1–3 pairs. Of all domesticated animals, they are absent only in dogs.

Location

Bulbourethral glands are located posterior and lateral to the membranous portion of the

urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...

at the base of the

penis A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urinate. The term ''pen ...

, between the two layers of the

fascia A fascia (; : fasciae or fascias; adjective fascial; ) is a generic term for macroscopic membranous bodily structures. Fasciae are classified as superficial, visceral or deep, and further designated according to their anatomical location. ...

of the

urogenital diaphragm Older texts have asserted the existence of a urogenital diaphragm, also called the triangular ligament, which was described as a layer of the pelvis that separates the deep perineal sac from the upper pelvis, lying between the inferior fascia of ...

, in the

deep perineal pouch The deep perineal pouch (also deep perineal space) is the anatomic space enclosed in part by the perineum and located superior to the perineal membrane. Structure The deep perineal pouch is bordered inferiorly by the perineal membrane, also kno ...

. They are enclosed by transverse fibers of the sphincter urethrae membranaceae muscle.

Structure

The bulbourethral glands are compound tubulo-alveolar glands, each approximately the size of a

pea Pea (''pisum'' in Latin) is a pulse or fodder crop, but the word often refers to the seed or sometimes the pod of this flowering plant species. Peas are eaten as a vegetable. Carl Linnaeus gave the species the scientific name ''Pisum sativum' ...

in humans. In chimpanzees, they are not visible during dissection, but can be found on microscopic examination. In

boars The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a Suidae, suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The speci ...

, they are up to 18 cm long and 5 cm in diameter. They are composed of several

lobules In anatomy, a lobe is a clear anatomical division or extension of an organ (as seen for example in the brain, lung, liver, or kidney) that can be determined without the use of a microscope at the gross anatomy level. This is in contrast to the mu ...

held together by a fibrous covering. Each lobule consists of a number of

acini An acinus (; : acini; adjective, acinar or acinous) refers to any cluster of cells that resembles a many-lobed "berry", such as a raspberry (''acinus'' is Latin for "berry"). The berry-shaped termination of an exocrine gland, where the secret ...

, lined by columnar

epithelial cells Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

, opening into a duct that joins with the ducts of other lobules to form a single excretory duct. This duct is approximately 2.5 cm long and opens into the bulbar urethra at the base of the penis. The glands gradually diminish in size with advancing age.''

Gray's Anatomy ''Gray's Anatomy'' is a reference book of human anatomy written by Henry Gray, illustrated by Henry Vandyke Carter and first published in London in 1858. It has had multiple revised editions, and the current edition, the 42nd (October 2020 ...

'', 38th ed., p 1861.

Function

The bulbourethral gland contributes up to 4 ml of fluid during sexual arousal. The secretion is a clear fluid rich in mucoproteins that help to lubricate the distal

and neutralize any acidic

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

residue that remains in the urethra. According to one preliminary study, the bulbourethral gland fluid might not contain any

sperm Sperm (: sperm or sperms) is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm ...

, whereas another study showed some men did leak sperm in potentially significant quantities (in a range from low counts up to 50 million sperm per ml) into the pre-ejaculatory fluid, potentially leading to conception from the introduction of

pre-ejaculate Pre-ejaculate (also known as pre-ejaculatory fluid, pre-seminal fluid or Cowper's fluid, and colloquially as pre-cum) is a clear, colorless, viscous fluid that is emitted from the urethra of the penis during sexual arousal and in general during ...

. However, the sperm source is a residual or pre-ejaculatory leak from the testicles into the vasa deferentia, rather than from the bulbourethral gland itself.

Gallery

File:Illu penis.jpg, Structure of the penis File:Gray1136.png, Male pelvic organs seen from right side File:Gray1156.png, Vertical section of bladder, penis, and urethra File:Gray543.png, Bulbourethral gland labeled at center left

References

{{DEFAULTSORT:Bulbourethral Gland Exocrine system Glands Human male reproductive system Mammal male reproductive system Sex organs

Location

Structure

Function

Gallery

See also

References