| Seminal vesicle | |
|---|---|
 Cross-section of the lowerabdomen in a male, showing parts of theurinary tract andmale reproductive system, with the seminal vesicles seen top right | |
 The seminal vesicles seen near theprostate, viewed from in front and above. | |
| Details | |
| Precursor | Mesonephric ducts |
| System | Male reproductive system |
| Artery | Inferior vesical artery,middle rectal artery |
| Lymph | External iliac lymph nodes,internal iliac lymph nodes |
| Identifiers | |
| Latin | vesiculae seminales, glandulae vesiculosae |
| MeSH | D012669 |
| TA98 | A09.3.06.001 |
| TA2 | 3631 |
| FMA | 19386 |
| Anatomical terminology | |
Theseminal vesicles (also calledvesicular glands[1] orseminal glands) are a pair of convoluted tubularaccessory glands that lie behind theurinary bladder ofmale mammals. They secrete fluid that largely composes thesemen.
The vesicles are 5–10 cm (2.0–3.9 in) in size, 3–5 cm (1.2–2.0 in) in diameter, and are located between thebladder and therectum. They have multiple outpouchings, which contain secretory glands, which join together with thevasa deferentia at theejaculatory ducts. They receive blood from thevesiculodeferential artery, and drain into the vesiculodeferential veins. The glands are lined withcolumn-shaped andcuboidal cells. The vesicles are present in many groups of mammals, but not marsupials, monotremes or carnivores.[citation needed].
Inflammation of the seminal vesicles is called seminal vesiculitis and most often is due to bacterial infection as a result of asexually transmitted infection or following a surgical procedure. Seminal vesiculitis can cause pain in the lower abdomen, scrotum, penis orperitoneum, painfulejaculation, andblood in the semen. It is usually treated with antibiotics, although may require surgical drainage in complicated cases. Other conditions may affect the vesicles, including congenital abnormalities such as failure or incomplete formation, and, uncommonly, tumours.
The seminal vesicles have been described as early as the second century AD byGalen, although the vesicles only received their name much later, as they were initially described using the term from which the wordprostate is derived.
The human seminal vesicles are a pair of glands in males that are positioned below theurinary bladder and at the end of thevasa deferentia, where they enter theprostate. Each vesicle is a coiled and folded tube, with occasional outpouchings termed diverticula in its wall.[2] The lower part of the tube ends as a straight tube called theexcretory duct, which joins with the vas deferens of that side of the body to form anejaculatory duct. The ejaculatory ducts pass through the prostate gland before opening separately into theverumontanum of the prostaticurethra.[2] The vesicles are between 5–10 cm (2.0–3.9 in) in size, 3–5 cm (1.2–2.0 in) in diameter, and have a volume of around 13 mL.[3]
The vesicles receive blood supply from the vesiculodeferential artery, and also from theinferior vesical artery. Thevesiculodeferential artery arises from theumbilical arteries, which branch directly from theinternal iliac arteries.[3] Blood is drained into thevesiculodeferential veins and the inferior vesical plexus, which drain into theinternal iliac veins.[3]Lymphatic drainage occurs along the venous routes, draining into theinternal iliac nodes.[3]
The vesicles lie behind the bladder at the end of the vasa deferentia. They lie in the space between the bladder and therectum; the bladder and prostate lie in front, the tip of theureter as it enters the bladder above, andDenonvilliers' fascia and the rectum behind.[3]
In the developingembryo, at the hind end lies acloaca. This, over the fourth to the seventh week, divides into aurogenital sinus and the beginnings of theanal canal, with a wall forming between these two inpouchings called theurorectal septum.[4] Two ducts form next to each other that connect to the urogenital sinus; themesonephric duct and theparamesonephric duct, which go on to form thereproductive tracts of the male and female respectively.[4]
In the male, under the influence oftestosterone, the mesonephric ducts proliferate, forming theepididymis,ductus deferens and, via a small outpouching near the developing prostate, the seminal vesicles.[4]Sertoli cells secreteanti-Müllerian hormone, which causes the paramesonephric ducts to regress.[4]
The development and maintenance of the seminal vesicles, as well as their secretion and size/weight, are highly dependent onandrogens.[5][6] The seminal vesicles contain5α-reductase, which metabolizes testosterone into its much more potentmetabolite,dihydrotestosterone (DHT).[6] The seminal vesicles have also been found to containluteinizing hormone receptors, and hence may also be regulated by the ligand of this receptor,luteinizing hormone.[6]
The inner lining of the seminal vesicles (theepithelium) is made of a lining ofinterspersed column-shaped andcube-shaped cells.[8] There are varying descriptions of the lining as beingpseudostratified and consisting of column-shaped cells only.[9] Whenviewed under a microscope, the cells are seen to have large bubbles in their interior. This is because their interior, calledcytoplasm, contains lipid droplets involved in secretion during ejaculation.[8] The tissue of the seminal vesicles is full of glands, spaced irregularly.[8] As well as glands, the seminal vesicles containsmooth muscle andconnective tissue.[8] This fibrous and muscular tissue surrounds the glands, helping to expel their contents.[3] The outer surface of the glands is covered inperitoneum.[3]
The seminal vesicles secrete a significant proportion of the fluid that ultimately becomessemen.[10] Fluid is secreted from the ejaculatory ducts of the vesicles into the vas deferens andejaculated through the urethra during the malesexual response.[9]
About 70-85% of the seminal fluid in humans originates from the seminal vesicles.[11] The fluid consists of nutrients includingfructose andcitric acid,prostaglandins, andfibrinogen.[10]
Nutrients help supportsperm until fertilisation occurs; prostaglandins may also assist by softening mucus of thecervix, and by causing reverse contractions of parts of thefemale reproductive tract such as thefallopian 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), andcysts.[13][14] Failure of the vesicles to form is often associated with absent vas deferens, or an abnormal connection between the vas deferens and the ureter.[3] The seminal vesicles may also be affected bycysts,amyloidosis, andstones.[13][14] Stones or cysts that become infected, or obstruct the vas deferens or seminal vesicles, may require surgical intervention.[9]
Seminal vesiculitis (also known as spermatocystitis) is an inflammation of the seminal vesicles, most often caused by bacterial infection.[15] 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.[16] Infection may be due tosexually transmitted infections, as a complication of a procedure such as prostate biopsy.[9] It is usually treated withantibiotics. If a person experiences ongoing discomfort, transurethral seminal vesiculoscopy may be considered.[17][18] Intervention in the form of drainage through the skin or surgery may also be required if the infection becomes anabscess.[9] The seminal vesicles may also be affected bytuberculosis,schistosomiasis andhydatid disease.[13][14] These diseases are investigated, diagnosed and treated according to the underlying disease.[9]
Benign tumours of the seminal vesicles are rare.[9] When they do occur, they are usually papillary adenomata and cystadenomata. They do not cause elevation oftumour markers and are usually diagnosed based on examination of tissue that has been removed after surgery.[9] Primaryadenocarcinoma, although rare, constitutes the most common malignant tumour of the seminal vesicles;[19] that said, malignant involvement of the vesicles is typically the result of local invasion from an extra-vesicular lesion.[9] When adenocarcinoma occurs, it can cause blood in the urine, blood in the semen, painful urination, urinary retention, or even urinary obstruction.[9] Adenocarcinomata are usually diagnosed after they are excised, based on tissue diagnosis.[9] Some produce the tumour markerCa-125, which can be used to monitor for reoccurrence afterwards.[9] Even rarer neoplasms includesarcoma,squamous cell carcinoma,yolk sac tumour, neuroendocrine carcinoma,paraganglioma, epithelial stromal tumours andlymphoma.[19]
Symptoms due to diseases of the seminal vesicles may be vague and not able to be specifically attributable to the vesicles themselves; additionally, some conditions such as tumours or cysts may not cause any symptoms at all.[9] When diseases is suspected, such as due to pain on ejaculation,blood in the urine,infertility, due to urinary tract obstruction, further investigations may be conducted.[9]
Adigital 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).
A urine specimen may be collected, and is likely to demonstrate blood within the urine.[9] Laboratory examination of seminal vesicle fluid requires a semen sample, e.g. for semenculture orsemen analysis.Fructose levels provide a measure of seminal vesicle function and, if absent,bilateralagenesis or obstruction is suspected.[13]
Imaging of the vesicles is provided bymedical imaging; either bytransrectal ultrasound,CT orMRI scans.[9] An examination usingcystoscopy, 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.[9]
The evolution of seminal vesicles may have been influenced bysexual selection.[20] They occur in birds and reptiles[21] and many groups of mammals,[22] but are absent inmarsupials,[23][24]monotremes, andcarnivorans.[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 byGalen, as "glandular bodies" that secrete substances alongside semen during reproduction.[25] By the time ofHerophilus the presence of the glands and associated ducts had been described.[25] 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.[25] The first time the prostate was portrayed in an individual drawing was byRegnier De Graaf in 1678.[25]
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.[9]
{{cite book}}: CS1 maint: location missing publisher (link){{cite web}}: CS1 maint: multiple names: authors list (link) Last staff update: 20 November 2023{{cite book}}:|last1= has generic name (help)CS1 maint: multiple names: authors list (link)The humor produced in those glandular bodies is poured into the urinary passage in the male along with semen and its uses are to excite to the sexual act, to make coitus pleasurable, and to moisten the urinary passageway.
| International | |
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| Other | |
