seminales

Seminal vesicles, also known as vesiculae seminales, are a pair of elongated glands in the male reproductive system. They are located behind the bladder and in front of the rectum, near the junction of the vas deferens and the ejaculatory ducts, which pass through the prostate and open into the prostatic urethra.

Structure and function: Each vesicle is a convoluted, sac-like duct with a highly folded mucosa. The glands produce a thick, viscous fluid that is alkaline and rich in fructose, prostaglandins, and proteins. This fluid contributes the majority of the ejaculate’s volume and provides an energy source for sperm, enhances sperm motility, and influences female reproductive tract motility and environment.

Secretion and coagulation: Seminal vesicle fluid contains seminogelin I and II, which help semen coagulate shortly after ejaculation. The coagulum is later liquefied by enzymes such as prostate-specific antigen (PSA) produced by the prostate, allowing sperm to become motile again.

Development and clinical relevance: The seminal vesicles arise from the Wolffian (mesonephric) duct system under testosterone during embryonic development and mature at puberty. Clinically, vesicle disorders are uncommon but can include congenital absence or obstruction of the ducts, vesiculitis (inflammation), or tumors. Obstruction or inflammation can reduce semen volume or affect fertility. Diagnostic approaches include transrectal ultrasound or MRI to assess anatomy and duct patency.

In summary, the seminal vesicles play a key role in producing the major component of semen, supporting sperm viability and function through a specialized, fructose-rich secretory product.