The male reproductive system relies on specialized structures known as accessory glands to produce the liquid portion of semen. While the testes create the sperm cells, these glands secrete fluids that nourish, protect, and transport the sperm through the reproductive tract. This combined mixture is called seminal fluid. The three primary accessory glands are the seminal vesicles, the prostate gland, and the bulbourethral glands. Each gland contributes specific components that ensure the survival of sperm in the acidic environment of the female reproductive tract. Understanding the anatomy of these glands is essential for midwives when assessing male reproductive health and fertility.
The seminal vesicles are a pair of pouch-like glands located behind the urinary bladder. They produce about 60 to 70 percent of the total volume of seminal fluid. Their secretion is thick, yellowish, and rich in fructose, which provides energy for the swimming sperm. It also contains prostaglandins, substances that stimulate smooth muscle contractions in the female reproductive tract to help push the sperm upward toward the egg. The fluid empties into the ejaculatory duct just before ejaculation, mixing with sperm coming from the vas deferens.
The prostate is a single, walnut-sized gland that sits directly beneath the urinary bladder, wrapping entirely around the first part of the urethra. It secretes a milky, slightly alkaline fluid that makes up about 20 to 30 percent of semen volume. This alkalinity helps neutralize the acidic environment of the vagina, greatly increasing sperm lifespan. The prostate fluid also contains prostate-specific antigen (PSA) and enzymes that help keep semen fluid. Because the urethra runs right through the center of the prostate, any enlargement of this gland can quickly cause problems with passing urine.
Also known as Cowper's glands, the bulbourethral glands are two small, pea-sized structures located beneath the prostate at the base of the penis. They secrete a clear, slippery mucus directly into the spongy urethra before ejaculation. This fluid acts as a natural lubricant for sexual intercourse. More importantly, it neutralizes any traces of acidic urine left in the urethra, protecting passing sperm from being damaged.
Together, these secretions create a balanced fluid environment. Semen is not just a vehicle for sperm transport; it actively buffers acids, supplies nutrients, and activates sperm motility as they enter the female reproductive tract.
Disorders of the male accessory glands can significantly impact fertility and urinary health. Benign prostatic hyperplasia (BPH) is a non-cancerous enlargement of the prostate common in older men, leading to weak urine flow and frequent urination. Prostatitis, an inflammation or infection of the prostate, causes pelvic pain and painful urination. Additionally, infections of the seminal vesicles or prostate can alter the chemical balance of seminal fluid, reducing sperm motility and contributing to male infertility. Midwives must recognize these symptoms during family health histories and encourage prompt medical evaluation.