bulbourethral gland

{{Infobox anatomy

| Name = Bulbourethral gland

| Latin = glandula bulbourethralis

| Image = male anatomy 1.png

| Caption = Male anatomy

| Image2 = Bulbourethral_gland_--_very_high_mag.jpg

| Caption2 = Micrograph of bulbourethral gland. H&E stain.

| Width = 200

| Precursor = Urogenital sinus

| System =Male reproductive system

| Artery = Artery of the urethral bulb

| Vein =

| Nerve =

| Lymph =

}}The bulbourethral glands or Cowper's glands (named for English anatomist William Cowper) are two small exocrine and accessory glands in the reproductive system of many male mammals.{{Cite book |last=Liebich |first=Hans-Georg |url=https://books.google.com/books?id=AiISEAAAQBAJ&pg=SA12-PA81 |title=Veterinary Histology of Domestic Mammals and Birds 5th Edition: Textbook and Colour Atlas |date=2019-10-31 |publisher=5m Books Ltd |isbn=978-1-78918-106-7 |language=en}} They are homologous to Bartholin's glands 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.{{cite web|url=https://www.ippf.org/blogs/what-pre-ejaculatory-fluid-also-known-pre-cum-and-can-it-cause-pregnancy|title=What is pre-ejaculatory fluid (also known as pre-cum), and can it cause pregnancy?|publisher=International Planned Parenthood Federation|date=13 February 2019|access-date=21 July 2019}} The paired glands are found adjacent to the urethra just below the prostate, seen best by screening (medicine) MRI 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 and Cetacea. They are the only accessory reproductive glands in male monotremes. Placental mammals usually have one pair of bulbourethral glands, while male marsupials have 1–3 pairs.{{Cite book |last=Dixson |first=Alan F. |url=https://books.google.com/books?id=whcvEAAAQBAJ&pg=PA273 |title=Mammalian Sexuality: The Act of Mating and the Evolution of Reproduction |date=2021-06-03 |publisher=Cambridge University Press |isbn=978-1-108-69949-5 |language=en}}{{Cite book |last1=Armati |first1=Patricia J. |url=https://books.google.com/books?id=x3S5v971Nk0C&pg=PA86 |title=Marsupials |last2=Dickman |first2=Chris R. |last3=Hume |first3=Ian D. |date=2006-08-17 |publisher=Cambridge University Press |isbn=978-1-139-45742-2 |language=en}}{{Cite book |last1=Tyndale-Biscoe |first1=C. Hugh |url=https://books.google.com/books?id=HpjovN0vXW4C&pg=PA149 |title=Reproductive Physiology of Marsupials |last2=Renfree |first2=Marilyn |date=1987-01-30 |publisher=Cambridge University Press |isbn=978-0-521-33792-2 |language=en}} Of all domesticated animals, they are absent only in dogs.{{cite book |author=Mark McEntee |url=https://books.google.com/books?id=j87wTz362roC&pg=PA333 |title=Reproductive Pathology of Domestic Mammals |date=December 2, 2012 |publisher=Elsevier Science |isbn=978-0-323-13804-8 |page=333 |access-date=August 20, 2013}}

Location

Bulbourethral glands are located posterior and lateral to the membranous portion of the urethra at the base of the penis, between the two layers of the fascia of the urogenital diaphragm, in the deep perineal pouch. They are enclosed by transverse fibers of the sphincter urethrae membranaceae muscle.

Structure

File:Prostatic urethra.svg

The bulbourethral glands are compound tubulo-alveolar glands, each approximately the size of a pea in humans. In chimpanzees, they are not visible during dissection, but can be found on microscopic examination.{{cite book|author=Jeffrey H. Schwartz|title=Orang-utan Biology|url=https://books.google.com/books?id=K6XZOOinwPAC&pg=PA92|access-date=August 20, 2013|year=1988|publisher=Oxford University Press|isbn=978-0-19-504371-6|page=92}} In boars, they are up to 18 cm long and 5 cm in diameter. They are composed of several lobules held together by a fibrous covering. Each lobule consists of a number of acini, lined by columnar epithelial cells, 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, 38th ed., p 1861.{{Unreliable source?|failed=y|date=January 2013}}

Function

File:Pre cum 160717.jpg of a human penis]]

The bulbourethral gland contributes up to 4 ml of fluid during sexual arousal.{{cite journal|year=2010|last1=Killick|first1=S. R|title=Sperm content of pre-ejaculatory fluid|journal=Human Fertility|volume=14|issue=1|pages=48–52|last2=Leary|first2=C|last3=Trussell|first3=J|last4=Guthrie|first4=K. A|doi=10.3109/14647273.2010.520798|pmid=21155689|pmc=3564677}} The secretion is a clear fluid rich in mucoproteins that help to lubricate the distal urethra and neutralize any acidic urine residue that remains in the urethra.

According to one preliminary study, the bulbourethral gland fluid might not contain any sperm,{{cite journal|pmc=3455634|year=2003|last1=Zukerman|first1=Z|title=Short Communication: Does Preejaculatory Penile Secretion Originating from Cowper's Gland Contain Sperm?|journal=Journal of Assisted Reproduction and Genetics|volume=20|issue=4|pages=157–159|last2=Weiss|first2=D. B|last3=Orvieto|first3=R|doi=10.1023/A:1022933320700|pmid=12762415}} 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. 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.