The prostate gland and seminal vesicles are integral components of the male reproductive system. These organs, though distinct in their individual structures and functions, are closely related anatomically and work together to support male fertility. Understanding their roles is important for comprehending male reproductive health.
Anatomy and Individual Functions
The prostate gland is a walnut-sized organ positioned directly below the bladder, surrounding the urethra. Its primary function involves producing prostatic fluid, which accounts for 20% to 30% of the total semen volume. This fluid contains components, including citrate, zinc, and enzymes such as prostate-specific antigen (PSA) and acid phosphatase. During ejaculation, the prostate’s muscles contract, expelling this fluid into the urethra.
The seminal vesicles are a pair of coiled, sac-like glands located behind the bladder and just above the prostate. These glands are responsible for producing seminal fluid, which constitutes a significant portion, 60% to 80%, of the semen volume. Seminal fluid is rich in fructose, a sugar that serves as the primary energy source for sperm. It also contains prostaglandins and coagulating proteins like fibrinogen.
Collective Role in Semen Production
The secretions from the prostate and seminal vesicles combine with sperm, which are produced in the testes, and fluids from other glands to form semen. An ejaculate ranges from 2 to 5 milliliters in volume. This complex mixture supports sperm survival and motility for reproduction.
Fructose from the seminal vesicles provides the necessary energy for sperm to move effectively through the female reproductive tract. Prostaglandins, from the seminal vesicles, assist in sperm transport by stimulating muscle contractions in the female reproductive system and can help suppress the female immune response to sperm. Enzymes originating from the prostate, such as PSA and fibrinolysin, play a role in the liquefaction of semen after ejaculation, allowing sperm to become more mobile.
The combined fluids establish an alkaline environment, with semen having a pH range of 7.2 to 7.8. This alkalinity helps to neutralize the naturally acidic environment of the vagina, protecting sperm from damage and enhancing their chances of survival. Zinc, a component of prostatic fluid, contributes to stabilizing the DNA within sperm cells. Coagulating proteins from the seminal vesicles cause semen to initially thicken, while prostatic enzymes later break down this coagulum, facilitating sperm dispersal.
Common Health Concerns
The prostate gland is susceptible to several common health conditions, particularly as men age. Benign Prostatic Hyperplasia (BPH) involves a non-cancerous enlargement of the prostate. This enlargement can compress the urethra, which passes through the prostate, potentially affecting urinary flow.
Prostatitis refers to inflammation of the prostate gland, which can result from bacterial infections. Prostate cancer is another significant concern, being one of the most common cancers among men. This cancer originates in the peripheral zone of the prostate.
Issues affecting the seminal vesicles are less common but can occur. Seminal vesicle cysts are fluid-filled sacs that can develop due to obstruction or infection. Cysts may cause discomfort. Seminal vesiculitis is an inflammation of the seminal vesicles, often caused by bacterial infections, which can result in pain. Less frequently, seminal vesicles can be affected by stones or by tumors that have spread from other areas, such as the prostate or colon.