A bulbourethral gland, also called a Cowper's gland for anatomist William Cowper

William Cowper (anatomist)

William Cowper FRS was an English surgeon and anatomist, famous for his early description of what is now known as the Cowper's gland....

, is one of two small exocrine gland

Gland

A gland is an organ in an animal's body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface .- Types :...

s present in the reproductive system

Reproductive system

The reproductive system or genital system is a system of organs within an organism which work together for the purpose of reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. Unlike most organ systems, the sexes...

 of human males. They are homologous

Homology (biology)

Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...

 to Bartholin's gland

Bartholin's gland

The Bartholin's glands are two glands located slightly posterior and to the left and right of the opening of the vagina. They secrete mucus to lubricate the vagina and are homologous to bulbourethral glands in males...

s in females.

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

The bulbourethral glands are compound tubulo-alveolar glands

Alveolar gland

In contrast to tubular glands, in the second main variety of gland, the secretory portion is enlarged and the lumen variously increased in size. These are termed alveolar glands ....

, each approximately the size of a pea

Pea

A pea is most commonly the small spherical seed or the seed-pod of the pod fruit Pisum sativum. Each pod contains several peas. Peapods are botanically a fruit, since they contain seeds developed from the ovary of a flower. However, peas are considered to be a vegetable in cooking...

. They are composed of several lobules

Lobe (anatomy)

In anatomy, a lobe is a clear anatomical division or extension that can be determined without the use of a microscope This is in contrast to a lobule, which is a clear division only visible histologically....

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

Acinus

An acinus refers to any cluster of cells that resembles a many-lobed "berry," such as a raspberry...

, lined by columnar epithelial cells

Epithelium

Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...

, opening into a duct

Duct (anatomy)

In anatomy and physiology, a duct is a circumscribed channel leading from an exocrine gland or organ.-Types of ducts:Examples include:-Duct system:...

 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 urethra at the base of the penis. The glands gradually diminish in size with advancing age.

Function

During sexual arousal

Sexual arousal

Sexual arousal, or sexual excitement, is the arousal of sexual desire, during or in anticipation of sexual activity. Things that precipitate human sexual arousal are called erotic stimuli, or colloquially known as turn-ons. There are many potential stimuli, both physical or mental, which can cause...

 each gland produces a clear, viscous secretion known as pre-ejaculate

Pre-ejaculate

Pre-ejaculate is the clear, colorless, viscous fluid that emits from the urethra of a man's penis when he is sexually aroused. It is similar in composition to semen, but has some significant chemical differences...

. This fluid helps to lubricate the urethra for spermatozoa to pass through, neutralizing traces of acid

Acid

An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ic urine

Urine

Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

 in the urethra, and helps flush out any residual urine or foreign matter. It is possible for this fluid to pick up sperm

Sperm

The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...

, remaining in the urethral bulb from previous ejaculation

Ejaculation

Ejaculation is the ejecting of semen from the male reproductory tract, and is usually accompanied by orgasm. It is usually the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. In rare cases ejaculation occurs because of prostatic disease...

s, and carry them out prior to the next ejaculation. The Cowper's gland also produces some amount of prostate-specific antigen (PSA), and Cowper's tumors may increase PSA to a level that makes prostate cancer suspected.