As well as glands, the seminal vesicles contain smooth muscle and connective tissue. This fibrous and muscular tissue surrounds the glands, helping to expel their contents. The outer surface of the glands is covered in peritoneum. Function
The seminal vesicles secrete a significant proportion of the fluid that ultimately becomes semen. Fluid is secreted from the ejaculatory ducts of the vesicles into the vas deferens, where it becomes part of semen. This then passes through the urethra, where it is ejaculated during a male sexual response.About 70-85% of the seminal fluid in humans originates from the seminal vesicles. The fluid consists of nutrients including fructose and citric acid, prostaglandins, and fibrinogen. Nutrients help support sperm until fertilisation occurs; prostaglandins may also assist by softening mucous of the cervix, and by causing reverse contractions of parts of the female reproductive tract such as the fallopian tubes, to ensure that sperm are less likely to be expelled. Clinical significance
Disease
Diseases of the Seminal vesicles as opposed to that of prostate gland are extremely rare and are infrequently reported in the medical literature.Congenital anomalies associated with the seminal vesicles include failure to develop, either completely (agenesis) or partially (hypoplasia), and cysts. Failure of the vesicles to form is often associated with absent vas deferens, or an abnormal connection between the vas deferens and the ureter. The seminal vesicles may also be affected by cysts, amyloidosis, and stones.
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.