This, over the fourth to the seventh week, divides into a urogenital sinus and the beginnings of the anal canal, with a wall forming between these two inpouchings called the urorectal septum. Two ducts form next to each other that connect to the urogenital sinus; the mesonephric duct and the paramesonephric duct, which go on to form the reproductive tracts of the male and female respectively.In the male, under the influence of testosterone, the mesonephric duct proliferates, forming the epididymis, ductus deferens and, via a small outpouching near the developing prostate, the seminal vesicles. Sertoli cells secrete anti-mullerian hormone, which causes the paramesonephric duct to regress.The development and maintenance of the seminal vesicles, as well as their secretion and size/weight, are highly dependent on androgens. The seminal vesicles contain 5α-reductase, which metabolizes testosterone into its much more potent metabolite, dihydrotestosterone (DHT). The seminal vesicles have also been found to contain luteinizing hormone receptors, and hence may also be regulated by the ligand of this receptor, luteinizing hormone. Microanatomy
The inner lining of the seminal vesicles (the epithelium) is made of a lining of interspersed column-shaped and cube-shaped cells. There are varying descriptions of the lining as being pseudostratified and consisting of column-shaped cells only. When viewed under a microscope, the cells are seen to have large bubbles in their interior. This is because their interior, called cytoplasm, contains lipid droplets involved in secretion during ejaculation. The tissue of the seminal vesicles is full of glands, spaced irregularly.
Stones or cysts that become infected, or obstruct the vas deferens or seminal vesicles, may require surgical intervention.Seminal vesiculitis (also known as spermatocystitis) is an inflammation of the seminal vesicles, most often caused by bacterial infection. Symptoms can include vague back or lower abdominal pain; pain of the penis, scrotum or peritoneum; painful ejaculation; blood in the semen on ejaculation; irritative and obstructive voiding symptoms; and impotence. Infection may be due to sexually transmitted infections, as a complication of a procedure such as prostate biopsy. It is usually treated with antibiotics. If a person experiences ongoing discomfort, transurethral seminal vesiculoscopy may be considered. Intervention in the form of drainage through the skin or surgery may also be required if the infection becomes an abscess. The seminal vesicles may also be affected by tuberculosis, schistosomiasis and hydatid disease. These diseases are investigated, diagnosed and treated according to the underlying disease.Benign tumours of the seminal vesicles are rare. When they do occur, they are usually papillary adenomas and cystadenomas. They do not cause elevation of tumour markers, and are usually diagnosed based examination of tissue that has been removed after surgery. Primary adenocarcinoma of the seminal vesicles, although rare, constitutes the most common malignant cancer of the seminal vesicles; that said, the majority of malignant cancers affecting the vesicles are lesions that have extended into the vesicles from nearby parts of the body. When adenocarcinoma occurs, it can cause blood in the urine, blood in the semen, painful urination, urinary retention, or even urinary obstruction.