COWPER'S GLANDS: CHARACTERISTICS, FUNCTION, HISTOLOGY AND DISEASES - ANATOMY AND PHYSIOLOGY - 2024

The Cowper 's glands or bulbouretrales accessory glands are glands of the male reproductive system. Together with the two seminal vesicles and the prostate, these glands participate in the secretion of the non-cellular fraction of semen, that is, the liquid vehicle for the transport of sperm.

Its name derives from the English surgeon William Cowper, who discovered them in the 17th century. There are two glands, one right and one left, which are located at the base of the penis, below the prostate.

Histology of the bulbourethral glands (Source: Nephron via Wikimedia Commons)

Some authors consider that these glands are homologous to the vestibular glands present in the female reproductive system, in addition to the fact that their main function is to lubricate the urethra with the viscous secretion that characterizes them.

Like the prostate, the bulbourethral glands are subject to different pathological conditions related to injuries, inflammations, infections and tumors, benign or malignant.

General characteristics

- They are exocrine glands, that is, the content of their secretions is discharged out of the body.

- The product of its secretion is pre-ejaculatory, therefore, it is released before ejaculation occurs.

- The fluid they produce has a "washing" effect on the urine residues found in the urethral canal.

- This fluid helps to “thicken” the semen and contributes to providing an adequate medium for the mobility of the sperm.

Function

The accessory glands of the male reproductive system, including the bulbourethral glands or Cowper's glands, are responsible for the secretion of seminal fluid, which represents the non-cellular portion of semen. This liquid fulfills two fundamental general functions:

1- Nourish the sperm.

2- Provide a means of transport for ejaculated sperm within the female reproductive system.

The bulbourethral glands secrete a slimy, slippery substance that is responsible for lubricating the lining of the urethra, which is the common conduit for urine and semen in the male genitalia. After penis erection (sexual stimulation), this discharge is one of the first to be expelled.

This substance is a mixture of serous and mucous materials (including glycoproteins), and it has been shown to contain substances with an alkaline pH, which seems to "neutralize" the acidity of possible urine residues that can be found in the urethra and that of the vaginal fluids.

In addition, some studies carried out with experimental mice show that the secretions of the Cowper's glands play an important role in the coagulation of semen.

Other functions

The bulbourethral glands are also involved in the immune defense of the genitourinary tract, as they secrete glycoproteins such as prostate-specific antigen (PSA), which also helps to dissolve seminal clots, allowing free transit of sperm through the female genital tract.

Histology

Cowper's glands are compound tubuloalveolar glands, made up of simple cuboid or columnar epithelium, which are located at the base of the penis, just where the membranous urethra begins.

Like the prostate, these glands derive from the urogenital sinus or urethra, under the influence of endocrine and paracrine hormonal signals, especially the hormone dihydrotestosterone (DHT).

They are embedded in connective tissue and are found specifically between the ischiocavernosus and bulb cavernosum muscles of the penis.

These are two small glands (3-5 mm in diameter), which are shaped like a pea and are lined by a fibroelastic capsule composed of fibroblasts, smooth muscle cells, and skeletal muscle cells derived from the urogenital diaphragm.

From these capsules that cover them derive membranous partitions that divide each gland into a kind of internal "lobules".

Inside, these glands have excretory ducts 6 to 10 mm in length, which enter the wall of the urethral bulb and discharge their secretions there. They possess a line of "long" pyramidal cells that have large numbers of densely packed secretory granules.

Secretory pyramidal cells are characterized by the presence of flattened nuclei, small rounded mitochondria, a prominent Golgi complex, and large numbers of cytosolic granules.

Diseases

Although the best known glandular pathologies in the male reproductive system are those that affect the prostate, diseases related to the Cowper's glands are much more common and can be congenital or acquired lesions.

The most common acquired lesions are inflammatory, but there may also be infections, calcifications or neoplasms, as occurs with the prostate gland.

Congenital lesions are normally asymptomatic and these include cystic duct dilation or syringocele, however, they often represent a problem in relation to the differential diagnosis with more severe lesions.

Cowper syringocele

It is a rare deformity of the male urethra and is associated with distention of the main duct of the bulbourethral glands. Its origin is not fully understood, but it has been experimentally shown to be related to deficiencies in the growth factor TGF-β2.

Cowper's siringocele can be open or closed. In the first case, this pathology is observed as an inflammation similar to a distended cyst in the wall of the urethra, while in the second case there is an opening that allows the reflux of urine towards the syringocele.

Maizels et al. Have classified the lesions of the bulbourethral glands into four groups:

- Simple syringocele: which is a minimal dilation of the duct.

- Perforated syringocele: where a bulbous duct forms that drains into the urethra and looks like a diverticulum.

- Unperforated syringocele: which is also a bulbous duct similar to a submucosal cyst.

- Broken syringocele: where the remaining membrane in the urethra ruptures after the duct has dilated.

Cowperitis, an acquired injury

This acquired injury consists of gland inflammation, which can be an acute or chronic condition. Acute cowperitis presents with fever, malaise, and severe perineal pain; There may also be pain during defecation and acute urinary retention.

Stones or stones

Some diseases of the Cowper's glands are also related to calcification inside them, which is more common in elderly patients. These calcifications, calculi, or stones, usually consist of phosphate salts of calcium, magnesium, potassium, calcium carbonate, and calcium oxalate.

Neoplasms

Neoplasms are malignant tumors and in the bulbourethral glands they can develop and be identified as the deformation of the glands and the appearance of anaplastic cells, that is, cells that are poorly differentiated, with abnormal growth and orientation contrary to the other cells of the tissue to which they belong.

References

1. Brock, WA, & Kaplan, GW (1979). Lesions of Cowper's glands in children. The Journal of urology, 122 (1), 121-123.
2. Chughtai, B., Sawas, A., O'MALLEY, RL, Naik, RR, Ali Khan, S., & Pentyala, S. (2005). A neglected gland: a review of Cowper's gland. International journal of andrology, 28 (2), 74-77.
3. Gartner, LP, & Hiatt, JL (2006). Color textbook of histology ebook. Elsevier Health Sciences.
4. Kühnel, W. (2003). Color Atlas of Cytology, Histology and Microscopic Anatomy. Georg Thieme Verlag.
5. Whitney, KM (2018). Male Accessory Sex Glands. In Boorman's Pathology of the Rat (pp. 579-587). Academic Press.