The seminal glands, also known as seminal vesicles, are accessory components of the male reproductive system. They produce fluids that contribute to semen, playing an important role in the reproductive process and facilitating successful fertilization.
Anatomy and Location
The seminal glands are a pair of structures located deep within the male pelvis. Each gland is situated directly behind the urinary bladder and in front of the rectum. They are positioned superior to the prostate gland, with their lower ends converging towards its base.
Each seminal gland appears as a coiled, sac-like or tubular structure, typically measuring around 5 centimeters. The wall of each gland comprises an inner mucosal layer, a muscular layer of smooth muscle, and an outer adventitial layer. These glands connect with the vas deferens, forming the ejaculatory ducts, which then open into the prostatic urethra.
Primary Function
Seminal vesicles produce a substantial portion of the fluid that forms semen, contributing approximately 50% to 80% of its total volume. This fluid is yellowish, viscous, and alkaline. Its alkaline nature helps neutralize the acidic vaginal environment, supporting sperm survival.
A significant component is fructose, a sugar providing the primary energy source for sperm. The fluid also contains prostaglandins, which aid sperm motility by inducing contractions in the female reproductive tract and may help prevent immune recognition. Seminal fluid includes clotting factors that cause semen to initially coagulate after ejaculation, helping to keep sperm alive. Enzymes from the prostate gland then cause the semen to liquefy, allowing sperm to become fully motile. The muscular tissue within the seminal vesicles contracts during ejaculation, expelling this fluid into the ejaculatory ducts.
Common Conditions
Several conditions can affect the seminal glands, potentially impacting their function and contributing to various symptoms. These conditions include inflammation, the formation of fluid-filled sacs, and mineral deposits.
Seminal vesiculitis refers to the inflammation of the seminal vesicles, frequently resulting from bacterial infections. Individuals experiencing this condition might report pelvic pain, discomfort during ejaculation, and the presence of blood in their semen. This inflammation can manifest as either an acute, sudden onset or a chronic, persistent issue.
Cysts are fluid-filled lumps that can develop on the seminal vesicles. While many seminal vesicle cysts are present from birth, others can be acquired due to obstruction or inflammation within the gland. These cysts are often asymptomatic and discovered incidentally; however, larger cysts can lead to discomfort, including abdominal or pelvic pain, painful urination, or increased urinary urgency. In some instances, cysts may also be associated with male infertility.
Calcifications, also known as stones, are hardened mineral clumps that can form within the seminal vesicles. This is a rare occurrence. When present, these calcifications can cause pain and discomfort, particularly during ejaculation, and may potentially obstruct the flow of semen. Seminal vesicle calcifications are sometimes observed in individuals with certain underlying health conditions, such as diabetes, hyperparathyroidism, or genitourinary tuberculosis.