Other conditions may affect the vesicles, including congenital abnormalities such as failure or incomplete formation, and, uncommonly, tumours.

The human 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.

[3] Lymphatic drainage occurs along the venous routes, draining into the internal iliac nodes.

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.

[4] In the male, under the influence of testosterone, the mesonephric ducts proliferate, forming the epididymis, ductus deferens and, via a small outpouching near the developing prostate, the seminal vesicles.

[4] Sertoli cells secrete anti-Müllerian hormone, which causes the paramesonephric ducts to regress.

Nutrients help support sperm until fertilisation occurs; prostaglandins may also assist by softening mucus 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.

[10] Diseases of the seminal vesicles as opposed to that of prostate gland are extremely rare and are infrequently reported in the medical literature.

[12] Congenital anomalies associated with the seminal vesicles include failure to develop, either completely (agenesis) or partially (hypoplasia), and cysts.

[13][14] Stones or cysts that become infected, or obstruct the vas deferens or seminal vesicles, may require surgical intervention.

They do not cause elevation of tumour markers and are usually diagnosed based on examination of tissue that has been removed after surgery.

[9] A digital rectal examination, which involves a finger inserted by a medical practitioner through the anus, may cause greater than usual tenderness of the prostate gland, or may reveal a large seminal vesicle.

[9] Palpation is dependent on the length of index finger as seminal vesicles are located above the prostate gland and retrovesical (behind the bladder).

Fructose levels provide a measure of seminal vesicle function and, if absent, bilateral agenesis or obstruction is suspected.

[20] They occur in birds and reptiles[21] and many groups of mammals,[22] but are absent in marsupials,[23][24] monotremes, and carnivorans.

[25][20] 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.

[22] 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.