The bulbourethral glands (also known as Cowper’s glands) are a pair of exocrine glands located posterolaterally to the membranous urethra. These glands serve an important role in male reproduction, contributing to the final volume of semen by producing a lubricating mucus secretion containing glycoproteins and other substances such as DHT (dihydrotestosterone). Occasionally, these secretions may carry spermatozoa that remain in the urethra after a previous ejaculation. In this article, we shall look at the anatomy of the bulbourethral glands - their structure, vasculature and innervation.
Anatomically, the bulbourethral glands can be found in the deep perineal pouch of the male. They are situated posterolaterally to the membranous urethra and superiorly to the bulb of the penis. The ducts of the gland penetrate the perineal membrane alongside the membranous urethra and open into the proximal portion of the spongy urethra. The glands themselves can be described as compound tubulo-alveolar glands lined by columnar epithelium.
Embryologically, the bulbourethral glands are derived from the urogenital sinus, along with the bladder, prostate and urethra. Their development is greatly influenced by DHT (dihydrotestosterone). The arterial supply of the Bulbourethral Glands is derived from the arteries to the bulb of the penis and they are innervated by the hypogastric nerve and the pelvic nerve or pelvic branch of the pudendal nerve. The lymphatic drainage is into the internal and external iliac lymph nodes.
The main function of the bulbourethral glands is to secrete mucus which serves as lubrication for the urethra and the tip of the penis, as well as aiding in ejaculation by expelling any residue of urine, dead cells or mucous through the urethral meatus and neutralizing residual acidity in the male urethra. This is especially important as the acidic environment in the urethra is thought to reduce sperm motility.
The bulbourethral glands are therefore an integral component in male reproduction. Without their secretion of mucus, the ejaculate would become too acidic and sperm mobility would be drastically reduced. It is also possible that without this protective mucus, any residual urine, dead cells or bacteria in the urethra could cause infection.
The mucus produced by the bulbourethral glands not only serves a lubricating and protective function but also helps to balance the pH of the ejaculate and make it more favorable for sperm survival. Studies have suggested that the mucus acts as a “sperm reservoir”, allowing the semen to flow more smoothly, thus improving sperm motility.
In conclusion, the bulbourethral glands are a vital component of the male reproductive system. They produce a mucus secretion of glycoproteins and DHT which serves as a lubricant and neutralizer for the urethral environment. This mucus helps to enhance sperm motility and protect the sperm from the acidic environment in the urethra. Without this mucus, sperm motility would decrease and possible infection could occur.
