Seminal Vesicle Definition

Seminal vesicle contain a pair of secretory glands found in the males of a variety of mammals, which generate specific seminal plasma components. The seminal, prostate, and bulbourethral glands are supplementary glands found in male humans. However, not every species possesses these three. Seminal vesicles have loosely wound entities surrounded by muscle. These are located in the pelvic region, particularly under the bladder and beneath the prostate gland.

Seminal Vesicle Function

In certain animals, the seminal vesicle’s function is exclusive to males. These two minute glands are responsible for secretion, which means they create and discharge chemical substances or compounds into the body. Some of the components of semen are produced by the seminal glands. A male of our species, or any animal that possesses them, cannot breed without at least one functional vesicular gland. So, what is the function of the seminal vesicle? To find out, the male reproductive system as well as its functions deserve more investigation.

Sperm cells include gametes (sex cells) produced by adult testicles as a consequence of both activation of the hypothalamus and testosterone. All those cells consist of a head, body, and tail and carry the genetic information of the person who creates them (axial filament). Millions of sperm must exit a man’s body through ejaculation in order for him to procreate normally. The number of sperm that leave the body varies depending on a variety of conditions, but on average, between 80 and 300 million sperm leave the body at any particular moment.

The sympathetic nervous system controls ejaculation by contracting the muscular layers of the reproductive canal. This motion forces seminal plasma as well as sperm cells towards the urethra. Semen (seminal fluid) and seminal plasma are not the same. The distinction between the two is determined by whether or not spermatozoa are present; seminal fluid is a mixture of sperm and seminal plasma.

Sperm cells can’t use their tails for migration without seminal plasma via the female reproductive system. Furthermore, all spermatozoa need energy throughout their entire cycle as living cells. Seminal plasma, the bulk of this substance, which is produced in the seminal vesicles, aids sperm motility and protects sperm from the vaginal acidic medium, prevents sperm from wriggling about and migrating too early (which loses energy), and gives sperm cells energy.

Water, salts, carbohydrates, lipids, proteins, bacteria, vitamins, hormones, and minerals make up seminal plasma. Seminal glands aren’t present in every male animal; carnivores, for example, lack seminal vesicles and instead create seminal plasma in the prostate gland. Humans have been considered evolutionarily herbivores, but this is merely a supposition—rabbits don’t have them, and we haven’t seen carnivorous rabbits yet. Nobody knows why certain animals lack seminal glands while others do.

Seminal Vesicle Anatomy

The anatomy of seminal vesicles is uncomplicated, since these glands only produce seminal plasma. Behind the prostate gland, between both the fundus (underside) of the bladder and the rectum, lies the seminal vesicle. The location of one seminal gland is shown in the diagram that follows. If shown, the other will be close by, to the left. The ampullae of the ductus are enlarged portions of the left and right vas deferens that enter into the seminal gland ejaculatory channels.

The vasa deferentia are two long tubes that transport spermatozoa, seminal plasma, or seminal plasma constituents from the right and left testes towards the urethra through the epididymides (plural of epididymis). The vas deferens consists of one tube.

These thin, right and left bulbourethral glands (Cowper’s glands) are connected by hollow tubes before reaching the prostate gland. Cowper’s glands produce an alkaline, viscous fluid. Each of the vasa deferentia expands as it passes past the core of the prostate gland, becoming the ampulla of the ductus. Here, the seminal glands expel their secretions. Every vas deferens discharges into a separate urethra after entering the prostate gland. The bladder is the bigger spherical component at the top of the figure below.

Histology of seminal vesicles shows three unique layers: a pseudostratified columnar epithelial lining (mucosa), a longitudinal and circular muscle layer, and a connective tissue layer. When activated by the sympathetic nervous system, the muscle layers contract and force seminal fluid out from the glands and into the vas deferens. The broader sections of the vasa deferentia at the ductus ampullae can deal with huge amounts of seminal plasma in a hurry; furthermore, they prevent fluid from leaking back into the glands.

Many goblet cells produce mucins in the pseudostratified columnar epithelium. These mucins make it simpler for sperm to drive themselves ahead by using their tails. The presence and synthesis of the hormone testosterone cause pseudostretified columnar epithelium cells to expand in height; if a man’s testosterone levels are low, this layer of epithelium thins, and whatever seminal fluid is produced is of low quality. Poor-quality seminal plasma, such as reduced sperm count or poor sperm quality, may cause reproductive issues.

Seminal Fluid

These seminal glands of male humans produce the vast bulk of seminal fluid or sperm; testes, epididymides, and the additional two accessory glands generate just trace quantities. In human males and other animals, seminal vesicles are present in the seminal, bulbourethral, and prostate glands.

Close to 5 percent of seminal fluid is produced by the testes, up to 30 percent by the epididymides and prostate, fewer than 1 percent by the bulbourethral glands, and between 60 and 75 percent by the seminal vesicles. Even though sperm cells are active cells, the fluid in which they move includes a variety of substances that increase their possibilities for longevity and performance in identifying and penetrating a female egg. Seminal plasma contains all the elements required for reproduction.

Components of seminal plasma are generated all through the male reproductive system. Both Sertoli cells and Leydig cells, which are present in the testes, produce spermatid carrier fluid and androgen (male) hormones, respectively. Glycerol, immobilin, and quiescence factor are produced by the epididymides, which are positioned right above the testes. Prior to ejaculation, immobilin as well as quiescence factor prohibit sperm cells from migrating and wasting energy. whereas glycerol shields them.

Ergothioneine is secreted by the ductus’ ampulla and is thought to operate like an antioxidant, safeguarding the sperm against toxins. Each bulbourethral gland produces alkaline mucus. This increases sperm mobility and decreases seminal fluid acidity. Because the female reproductive system is notoriously acidic, this is critical.

Before contributing prostate fluid, these seminal vesicles contribute mucoids that promote motility, sources of energy such as carbohydrates and citric acid, and defensive compounds such as ergothioneine. Citric acid is a crucial organic acid which facilitates the energy conversion of carbohydrates, lipids, and proteins.

Zinc, coagulants, water, citric acid, and acid phosphatase are administered to this thicker fluid when it passes through the prostate gland during ejaculation; the end product is called semen or seminal plasma.

Seminal Vesicle Pain

Most prevalent are infections of the male reproductive or urinary systems, which cause seminal vesicle discomfort. Prostatitis, urethritis, and cystitis are the most prevalent infections. Infections spread rapidly because the male reproductive tract shares the urethra with the urinary system. Seminal vesiculitis or spermatocystitis may occur when bacteria infect the seminal glands.

As a result of a seminal vesicle abscess, ejaculate may be malodorous, denser than normal (pus), and yellow. Seminal vesicle infections are more common post-surgery, in people with diabetes, and also in people who must use urinary catheters for a lengthy period of time. Any infection of the urinary or reproductive systems that goes untreated might result in lifelong infertility.

The basic constituents of seminal plasma become unbalanced as a result of seminal vesicle inflammation. By reducing sperm nutrition, motility, and immunity, infection of the male reproductive organs or urinary tract might reduce the chances of successful reproduction if left untreated. Antibiotics are frequently used to treat seminal gland infections.

A guy may never know whether he has a benign (non-cancerous) seminal vesicle cyst. There are few symptoms as long as it remains tiny. When a cyst becomes large enough, it may crush the seminal tube, causing localised discomfort, severe ejaculation, difficult urinating, and often invisible blood in the sperm. Stenosis in one of the vas deferens causes seminal gland cysts by preventing the affected gland from discharging properly. It becomes swollen, enlarged, and irritated. The vast majority of lesions are hereditary and originate from a single seminal vesicle.

Calculi (seminal vesicles) are exceedingly uncommon. They arise when the vas deferens narrows, allowing seminal fluid to flow retrograde into the gland. The seminal plasma becomes stagnant, allowing proteins and/or salts to crystallise or form stones. Protein accumulation is often the source of the very rare seminal vesicle stones that have been examined.

Seminal gland stones may obstruct urine flow and cause illness. If seminal vesicle stones impede the gland’s channel, they should be torn up with lithotripsy (shock waves delivered via the skin) or removed surgically. Cancer of the seminal vesicles is very rare only if it arises as a result of metastasis, or cancer spreading from another organ, such as the prostate, bladder, or rectum.

References

• McKay AC. “Anatomy, Abdomen and Pelvis, Seminal Vesicle.” [Updated 2020 Mar 4]. StatPearls Publishing; 2020 Jan, https://www.ncbi.nlm.nih.gov/books/NBK499854/
• Hopkins B. “Seminal fluid.” Current Biology; Jun. 2017; 27:11, https://www.cell.com/current-biology/fulltext/S0960-9822(17)30363-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982217303639%3Fshowall%3Dtrue
• Zaidi S., et al. “Etiology, diagnosis, and Management of Seminal Vesicle Stones”. Current Urology; 2018;12:113-120, https://www.karger.com/Article/FullText/489429