An examination using cystoscopy, where a flexible tube is inserted in the urethra, may show disease of the vesicles because of changes in the normal appearance of the nearby bladder trigone, or prostatic urethra. Other animals
The evolution of seminal vesicles may have been influenced by sexual selection. They occur in many groups of mammals, but are absent in marsupials, monotremes, and carnivoras. The function is similar in all mammals they are present in, which is to secrete a fluid as part of semen that is ejaculated during the sexual response. History
The action of the seminal vesicles has been described as early the second century AD by Galen, as "glandular bodies" that secrete substances alongside semen during reproduction. By the time of Herophilus the presence of the glands and associated ducts had been described. Around the time of the early 17th century the word used to describe the vesicles, parastatai, eventually and unambiguously was used to refer to the prostate gland, rather than the vesicles. The first time the prostate was portrayed in an individual drawing was by Reiner De Graaf in 1678.The first described use of laparoscopic surgery on the vesicles was described in 1993; this is now the preferred approach because of decreased pain, complications, and a shorter hospital stay.
Structure
The seminal vesicles are a pair of glands in males that are positioned below the urinary bladder and at the end of the vasa deferentia, where they enter the prostate. Each vesicle is a coiled and folded tube, with occasional outpouchings termed diverticula in its wall. The lower part of the tube ends as a straight tube called the excretory duct which joins with the vas deferens of that side of the body to form an ejaculatory duct. The ejaculatory ducts pass through the prostate gland before opening separately into the verumontanum of the prostatic urethra. The vesicles are between 5–10 cm in size, 3–5 cm in diameter, and have a volume of around 13 mL.The vesicles receive blood supply from the vesiculodeferential artery, and also from the inferior vesical artery. The vesiculodeferential artery arises from the umbilical arteries, which branch directly from the internal iliac arteries. Blood is drained into the vesiculodeferential veins and the inferior vesical plexus, which drain into the internal iliac veins. Lymphatic drainage occurs along the venous routes, draining into the internal iliac nodes.The vesicles lie behind the bladder at the end of the vasa deferentia. They lie in the space between the bladder and the rectum; the bladder and prostate lie in front, the tip of the ureter as it enters the bladder above, and Denonvilliers fascia and the rectum behind. Development
In the developing embryo, at the hind end lies a cloaca.