Semen is an organic fluid, also known as seminal fluid, that usually contains spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize female ova. In humans, seminal fluid contains several components besides spermatozoa: proteolytic and other enzymes as well as fructose are elements of seminal fluid which promote the survival of spermatozoa and provide a medium through which they can move or "swim." The process that results in the discharge of semen is called ejaculation.
Depending on the species, spermatozoa can fertilize ova externally or internally. In external fertilization, the spermatozoa fertilize the ova directly, outside of the female's sexual organs. Female fish, for example, spawn ova into their aquatic environment, where they are fertilized by the semen of the male fish.
During internal fertilization, however, fertilization occurs inside the female's sexual organs. Internal fertilization takes place after insemination of a female by a male through copulation. In low vertebrates (amphibians, reptiles, birds and monotreme mammals), copulation is achieved through the physical mating of the cloaca of the male and female. In marsupial and placental mammals, copulation occurs through the vagina.
During the process of ejaculation, sperm passes through the ejaculatory ducts and mixes with fluids from the seminal vesicles, the prostate, and the bulbourethral glands to form the semen. The seminal vesicles produce a yellowish viscous fluid rich in fructose and other substances that makes up about 70% of human semen. The prostatic secretion, influenced by dihydrotestosterone, is a whitish (sometimes clear), thin fluid containing proteolytic enzymes, citric acid, acid phosphatase and lipids. The bulbourethral glands secrete a clear secretion into the lumen of the urethra to lubricate it.
Sertoli cells, which nurture and support developing spermatocytes, secrete a fluid into seminiferous tubules that helps transport sperm to the genital ducts. The ductuli efferentes possess cuboidal cells with microvilli and lysosomal granules that modify the semen by reabsorbing some fluid. Once the semen enters the ductus epididymis the principle cells, which contain pinocytotic vessels indicating fluid reabsorption, secrete glycerophosphocholine which most likely inhibits premature capacitation. The accessory genital ducts, the seminal vesicle, prostate glands, and the bulbourethral glands, produce most of the seminal fluid.
The seminal plasma provides a nutritive and protective medium for the spermatozoa during their journey through the female reproductive tract. The normal environment of the vagina is a hostile one for sperm cells, as it is very acidic (from the native microflora producing lactic acid), viscous, and patrolled by immune cells. The components in the seminal plasma attempt to compensate for this hostile environment. Basic amines such as putrescine, spermine, spermidine and cadaverine are responsible for the smell and flavor of semen. These alkaline bases counteract the acidic environment of the vaginal canal, and protect DNA inside the sperm from acidic denaturation.
The components and contributions of semen are as follows:
|testes||2-5%||Approximately 200- to 500-million spermatozoa (also called sperm or spermatozoans), produced in the testes, are released per ejaculation.|
|seminal vesicle||65-75%||amino acids, citrate, enzymes, flavins, fructose (the main energy source of sperm cells, which rely entirely on sugars from the seminal plasma for energy), phosphorylcholine, prostaglandins (involved in suppressing an immune response by the female against the foreign semen), proteins, vitamin C|
|prostate||25-30%||acid phosphatase, citric acid, fibrinolysin, prostate specific antigen, proteolytic enzymes, zinc (serves to help to stabilize the DNA-containing chromatin in the sperm cells. A zinc deficiency may result in lowered fertility because of increased sperm fragility. Zinc deficiency can also adversely affect spermatogenesis.)|
|bulbourethral glands||< 1%||galactose, mucus (serve to increase the mobility of sperm cells in the vagina and cervix by creating a less viscous channel for the sperm cells to swim through, and preventing their diffusion out of the semen. Contributes to the cohesive jelly-like texture of semen.), pre-ejaculate, sialic acid|
A 1992 World Health Organization report described normal human semen as having a volume of 2 ml or greater, pH of 7.2 to 8.0, sperm concentration of 20x106 spermatozoa/ml or more, sperm count of 40x106 spermatozoa per ejaculate or more, and motility of 50% or more with forward progression (categories a and b) of 25% or more with rapid progression (category a) within 60 minutes of ejaculation.
Most semen is white, but grey or even yellowish semen can be normal as well. Blood in the semen can cause a pink or reddish colour, known as hematospermia, and may indicate a medical problem which should be evaluated by a doctor if it does not readily disappear.
After ejaculation, semen first goes through a clotting process and then becomes more liquid. It is postulated that the initial clotting helps keep the semen in the vagina, but liquefaction frees the sperm to make their long journey to the ova. Immediately after ejaculation semen is typically a sticky, jelly-like liquid often forming globules. Within 5 to 40 minutes it will become more watery and liquid before finally drying.
Semen quality is a measure of the ability of semen to accomplish fertilization. Thus, it is a measure of fertility in a man. It is the sperm in the semen that is the fertile component, and therefore semen quality involves both sperm quantity and sperm quality.
In addition to its central role in reproduction, various scientific findings indicate that semen has certain beneficial effects on human health, both proven benefits and possible benefits:
Further research, such as that by Mathur and Goust, demonstrated that non-preexisting antibodies were produced in humans in response to the sperm. These antibodies mistakenly recognized native T lymphocytes as foreign antigens, and consequently T lymphocytes would fall under attack by the body's B lymphocytes.
Semen contains proteins with potent bactericidal activity but these proteins are not active against Neisseria gonorrhoeae a common cause of sexually transmitted disease.
The presence of blood in semen or hematospermia may be undetectable (it only can be seen microscopically) or visible in the fluid. Its cause could be the result of inflammation, infection, blockage, or injury of the male reproductive tract or a problem within the urethra, testicles, epididymis and prostate.
In rare cases, people have been known to experience allergic reactions to seminal fluids, known as human seminal plasma hypersensitivity. Symptoms can be either localized or systemic, and may include vaginal itching, redness, swelling, or blisters within 30 minutes of contact. They may also include generalized itching, hives, and even difficulty breathing.
One way to test for human seminal plasma sensitivity is to use a condom during intercourse. If symptoms dissipate with the use of a condom, it is possible that a sensitivity to semen is present. Mild cases of semen allergy can often be overcome by repeated exposure to seminal fluid. In more severe cases, it is important to seek the advice of a physician, particularly in the event that a couple is trying to conceive, in which case, artificial insemination may be indicated.
A recent study has suggested that semen acts as an antidepressant in women, so that women physically exposed to semen are less likely to suffer from depression. It is thought that the psychological effects of semen are a result of its complex chemical make-up including several mood-altering hormones (testosterone, oestrogen, follicle-stimulating hormone, luteinizing hormone, prolactin and several different prostaglandins). In a scientific survey of 293 college women it was also found that those who did not use condoms were most likely to initiate sex and to seek out new partners as soon as a relationship ended, suggesting that the chemical dependency to semen creates a "rebound effect". The effect of semen on a male sexual partner (a receiver of semen) is not known.
Qigong and Chinese medicine place huge emphasis on a form of energy called 精 (pinyin: jīng, also a morpheme denoting "essence" or "spirit") - which one attempts to develop and accumulate. "Jing" is sexual energy and is considered to dissipate with ejaculation so masturbation is considered "energy suicide" amongst those who practice this art. According to Qigong theory, energy from many pathways/meridians becomes diverted and transfers itself to the sexual organs during sexual excitement. The ensuing orgasm and ejaculation will then finally expel the energy from the system completely. The Chinese proverb 一滴精，十滴血 (pinyin: yì dī jīng, shí dī xuè, literally: a drop of semen is equal to ten drops of blood) illustrates this point.
The scientific term for semen in Chinese is 精液 (pinyin: jīng yè, literally: fluid of essence/jing) and the term for sperm is 精子 (pinyin: jīng zǐ, literally: basic element of essence/jing), two modern terms with classical reference.
In Ancient Greece, Aristotle remarked on the importance of semen: "For Aristotle, semen is the residue derived from nourishment, that is of blood, that has been highly concocted to the optimum temperature and substance. This can only be emitted by the male as only the male, by nature of his very being, has the requisite heat to concoct blood into semen." According to Aristotle, there is a direct connection between food and semen: "Sperms are the excretion of our food, or to put it more clearly, as the most perfect component of our food."
The connection between food and physical growth, on the one hand, and semen, on the other, allows Aristotle to warn against "engag[ing] in sexual activity at too early an age ... [since] this will affect the growth of their bodies. Nourishment that would otherwise make the body grow is diverted to the production of semen.... Aristotle is saying that at this stage the body is still growing; it is best for sexual activity to begin when its growth is 'no longer abundant', for when the body is more or less at full height, the transformation of nourishment into semen does not drain the body of needed material."
Additionally, "Aristotle tells us that the region round the eyes was the region of the head most fruitful of seed ("most seedy" σπερματικώτατος), pointing to generally recognised effects upon the eyes of sexual indulgence and to practices which imply that seed comes from liquid in the region of the eyes." This may be explained by the belief of the Pythagoreans that "semen is a drop of the brain [τὸ δε σπέρμα εἶναι σταγόνα ἐγκέφαλου]."
Greek Stoic philosophy conceived of the Logos spermatikos ("seminal word") as the principle of active reason that fecundated passive matter. The Jewish philosopher Philo similarly spoke in sexual terms of the Logos as the masculine principle of reason that sowed seeds of virtue in the feminine soul.
The Christian Platonist Clement of Alexandria likened the Logos to physical blood as the "substance of the soul," and noted that some held "that the animal semen is substantially foam of its blood". Clement reflected an early Christian view that "the seed ought not be wasted nor scattered thoughtlessly nor sown in a way it cannot grow."
In some pre-industrial societies, semen and other body fluids were revered because they were believed to be magical. Blood is an example of such a fluid, but semen was also widely believed to be of supernatural origin and effect and was, as a result, considered holy or sacred.
Dew was once thought to be a sort of rain that fertilized the earth and, in time, became a metaphor for semen. The Bible employs the term “dew” in this sense in such verses as Song of Solomon 5:2 and Psalm 110:3, declaring, in the latter verse, for example, that the people should follow only a king who was virile enough to be full of the “dew” of youth.
It was widely believed, in ancient times, that gemstones were drops of divine semen which had coagulated after having fertilized the earth. There is an ancient Chinese belief that jade, in particular, was the dried semen of the celestial dragon.
Based upon the resemblance of dandelion juice to human semen, it was historically believed that the flower magically promoted the flow of sperm. (This belief probably derives from the doctrine of signatures.)
Barbara G. Walker recounts these examples of sacred semen in The Woman’s Dictionary of Symbols and Sacred Objects, the thesis of which is that myth and folklore show a pre-patriarchic rule by women that was later supplanted by masculine culture.
In primitive mythology around the world, semen is very often considered analogous to breast milk in some way. In the traditions of Bali, it is considered to be the returning or refunding of the milk of the mother in an alimentary metaphor. The wife feeds her husband who returns to her his semen, the milk of human kindness, as it were.
In some systems of medical philosophy, such as traditional Russian medicine and the Vital Force theory of Herbert Nowell, semen is regarded as the product of a complex physiological interaction between a man and a woman (rather than merely the product of the male reproductive system).
Some reasons for human ingestion of human or other semen are erotic gratification and physical and spiritual benefits. The most common way that swallowing of semen occurs is when fellatio or irrumatio are performed to climax. Both sexes ingest semen. Men may consume their own semen after masturbation, sex, or autofellatio.
Semen is primarily water, but contains trace amounts of almost every nutrient the human body uses. It has somewhat higher amounts of commonly deficient minerals, such as potassium, magnesium, and selenium. One typical ejaculation contains 150 mg of protein, 11 mg of carbohydrates, 6 mg fat, 3 mg cholesterol, 7% US RDA potassium and 3% US RDA copper and zinc. When metabolized, protein yields 4 kcal/g, carbohydrate also yields 4 kcal/g, and fat yields 9 kcal/g. Hence the food energy in the typical ejaculation is 0.7 kcal (2.9 kJ).
There is no risk in ingesting the semen of a healthy man. Swallowing semen carries no additional risk other than those inherent in fellatio. Fellatio does carry some risk for sexually transmitted diseases such as HIV or herpes, however, HIV and all other viruses are inhibited by saliva and destroyed by stomach acid. Research has suggested that performing unprotected oral sex on a person infected with human papillomavirus (HPV) might increase the risk of oral or throat cancer. The study found that 36 percent of the cancer patients had HPV compared to only 1 percent of the healthy control group. It is believed that this is due to the transmission of HPV because this virus has been implicated in the majority of cervical cancers. Even if semen is cold before the individual ingests it, viruses can stay active for a long period of time once outside the body. Contracting diseases from oral sex is more likely if there are sores in the mouth.
One source has noted that "few women praise the taste" of semen. Although it is commonly reported that the taste of semen is significantly influenced by diet, there are no scientific studies that indicate which foods do so, nor are there likely to ever be.
The volume of semen ejaculate varies. A review of 30 studies concluded that the average was around 3.4 milliliters (ml), with some studies finding amounts as high as 4.99 ml or as low as 2.3 ml. In a study with Swedish and Danish men, a prolonged interval between ejaculations caused an increase of the sperm count in the semen but not an increase of its amount. Younger males tend to produce larger quantities.
In some cultures, semen is attributed with special properties of masculinity. Several tribes of Papua New Guinea, including the Sambia and the Etoro, believe that semen provides sexual maturation among the younger men of their tribe. To them, sperm possesses the manly nature of the tribal elders, and in order to pass down their authority and powers, younger men of their next generation must fellate their elders and ingest their semen. This custom commences among prepubescent males and postpubescents. This act may also be attributed to the culturally active homosexuality throughout these and other tribes.
The church father Epiphanius records that the Borborites and other libertine Gnostic sects consumed semen as the Body of Christ. The Pistis Sophia and Testimony of Truth harshly condemn such practices.
In the modern St. Priapus Church, consumption of semen in the presence of others is a form of worship. It is esteemed as sacred because of its divine life-giving power. Some chapters of the Ecclesia Gnostica Catholica practice the consumption of semen during the Gnostic Mass, composed by Aleister Crowley.
There are several sexual practices involving the ingestion of semen. They can be done with one or more partners, like snowballing, felching and creampie eating, or with multiple partners, like the practices of bukkake and gokkun, which originate from Japan.
Many men who experience erectile dysfunction or impotency have started using natural semen volume pills. These herbal pills are not approved by the Food and Drug Administration and fall under the male enhancement category. Semen volume pills are designed to increase the amount of ejaculation or semen volume during sex. The companies like Semenax and Volume Pills claim people can cure sexual health problems by increasing semen levels during ejaculation.
These herbal pills were introduced and have been promoted in the adult entertainment industry with adult porn star Ron Jeremy acting as a spokesman.
None of these claims have been verified and the FDA does not approve or recommend any herbal preparations for the purpose of increasing the volume of ejaculate.
Japanese artist Takashi Murakami is famous for a manga style piece entitled My Lonesome Cowboy, which features a naked cowboy superhero wielding his own semen as a lasso.
Andres Serrano, whose photos depict bodily fluids such as Blood and Semen II (Semen y sangre II) (1990), became a controversial figure for featuring semen in his work. He was criticized by some for producing offensive art, while others defended him in the name of artistic freedom. His photos were featured on the cover art of two Metallica albums, Load and ReLoad, which feature images made by shining light through a piece of clear plastic on which semen, blood and urine have been splattered and swirled around.
Only recently has semen been depicted (albeit controversially) in movies such as The Silence of the Lambs (1991), Kika (1993), There's Something About Mary (1998) ("a hard-core staple making its debut in a mainstream Hollywood comedy"), Happiness (1998), American Pie (1999), Scary Movie (2000), Y tu mamá también (2001), Scary Movie 2 (2001), Freddy Got Fingered (2001), National Lampoon's Van Wilder (2002) and Clerks II (2006). Jackass Number Two (2006) features a scene where Chris Pontius drinks the semen of a horse. It has also appeared in the anime movie End of Evangelion.
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Semen (pronounced SEE-men or SEE-mən) is the fluid that comes out from the end of a man's penis when he has an orgasm (the height of sexual excitement) and ejaculates. It is usually a white or yellowish, sticky substance made up of sperm (male cells for sexual reproduction) floating in a fluid called seminal plasma that has water and different chemicals in it. Normally, an ejaculation makes between 1.5 and 5 millilitres (up to one teaspoonful) of semen.
Some scientists think that semen that is taken into a woman's body causes her not to feel depressed or sad. On the other hand, if semen touches another person's body, it can pass on sexually transmitted infections (STIs). In a few cases, it can also make the other person's immune system weaker, or cause the person to have an allergic reaction. The risks of these health problems happening can be reduced if the man wears a condom when having sex.
Many cultures around the world once thought or still think that semen has special or even magical qualities. Showing semen in forms of popular culture such as art and movies has for a long time been taboo, that is, not generally accepted by society. However, since the late 20th century, artists and moviemakers have done so more often.
The English word semen comes from the Latin word sēmen, which means "seed". In fact, seed was an old-fashioned name for semen. The Latin word sēmen itself came from another Latin word, serěre, which means "to plant (a plant into the ground) or to sow (seeds in the earth)". It was once thought that semen was like a seed that grew into a baby after being "planted" inside a woman's body.
Another name for semen is ejaculate. Some slang words for semen are cream, cum, jism, jizz, load, spooge, spunk and wad.
Semen is the fluid that comes out from the end of a man's penis when he has an orgasm (the height of sexual excitement) and ejaculates. It is usually white, but may also be slightly grey or yellow. If there is blood in the semen, it can look pink or reddish. This is a condition called hematospermia, and may be because of some blockage, inflammation, infection or injury to some part of the male sex organs, such as the urethra, epididymis, prostate or testicles. A doctor should be seen if the pink or reddish colour does not go away after a few days.
Men ejaculate different amounts of semen. Normally, an ejaculation makes between 1.5 and 5 millilitres (up to one teaspoonful) of semen. More semen tends to come out if a man has not ejaculated for many days, or if he has been stimulated (made sexually excited) for a long time. Older men make less semen. If a man ejaculates an unusually small amount of semen, this is a medical condition called hypospermia.
After a man has ejaculated, semen first becomes slightly thick and sticky, and may feel a bit like jelly and clump together in globs. Scientists think that semen does this so that if the man has had sex with a woman and has ejaculated inside her vagina, the semen stays in her vagina for longer and does not leak out. Between five and 40 minutes after this, semen becomes more liquid and watery. This probably allows the sperm in the semen to move through the vagina and into the woman's uterus and Fallopian tubes to try and fertilize an ovum (egg cell). If semen is ejaculated outside the body, after becoming watery it eventually dries up.
Semen is made up of sperm (male cells for sexual reproduction) floating in a fluid called seminal plasma. Sperm, also called spermatozoa, are made by a man's testicles and mature (grow up) in the epididymis. The fluids in seminal plasma come from different glands in the man's body: the seminal vesicles, prostate and bulbourethral glands (also called the Cowper's glands). (Glands are special organs in the body that make chemicals.) The table below shows the substances that make up semen and the glands that produce them:
|Testicles and epididymis||5%|
|Bulbourethral (Cowper's) glands||5%||
Seminal plasma protects and provides food for sperm as they travel inside a woman's body. The inside of a woman'a vagina does not suit sperm cells as it is acidic. To protect the sperm from the acid, seminal plasma is alkaline. A woman's immune system also tries to kill organisms (living things) that are not part of her body. Seminal plasma has chemicals called prostaglandins in it to stop the woman's body from killing the sperm.
[[File:|thumb|A photograph of human sperm. Sperm are not really red and green in colour; the colours were added to the photograph to make the sperm stand out more clearly.]]
Semen quality refers to how well the sperm in a man's semen can fertilize a woman's ova. The better a man's semen quality, the more fertile (able to make a woman pregnant) he is. A 1992 World Health Organization book said that an ejaculation of normal human semen has:
The number of sperm in an ejaculation of semen depends on many things. There may be more sperm if:
If there are an unusually low number of sperm in an ejaculation, this is called oligospermia. If there are no sperm at all, this is called azoospermia. A man with oligospermia or azoospermia is usually infertile, and cannot or finds it very hard to make a woman pregnant by having sex with her.
[[File:|thumb|160px|Semen ejaculated by a man inside a condom. The end of a condom has a small pouch called a reservoir, which is a space for the semen. Wearing a condom helps to stop the spread of sexually transmitted infections.]]
Studies seem to say that semen is an anti-depressant. This means that it causes women not to feel depressed or sad. The studies found that when men had sex with women without using condoms, and the men's semen was taken into the women's vaginas, the women had better moods and felt happier. Scientists do not yet know if the same thing happens when semen is swallowed after oral sex, but some of them think it may.
If a man has a sexually transmitted infection or STI (an infection that is passed from one person to another by sex), the germs that cause the disease can appear in his semen. If the person that the man has sex with touches the semen, he or she can become infected by the germs and pick up the disease. AIDS, chlamydia, gonorrhea, hepatitis B, herpes and syphillis are examples of STIs. One of the ways for a man to lower the chance of passing on an STI to his sexual partner is to wear a condom on his penis when having sex.
Some scientists think that parts of semen, such as sperm and seminal plasma, can make another person's immune system weaker. Experiments show that when substances in a man's semen enter another person's body, that person's body makes antibodies. Antibodies are large Y-shaped proteins used by the body's immune system to stop foreign objects from harming the body. However, the antibodies made in response to substances in semen attack one of the body's own cells, called T lymphocytes. This weakens the body's immune system.
In a very small number of cases, people have experienced allergic reactions when they touched semen. This is called human seminal plasma hypersensitivity. The symptoms (signs of the medical problem) can either be near the part of the body which touched the semen, or all over the body. They may include itching of the vagina, redness, swelling or blisters within 30 minutes of contact. They may also include itching and hives (large, red, itchy patches) all over the body, and even difficulty breathing.
The best way to test for human seminal plasma hypersensitivity is for a man to use a condom when having sex. When a condom is used, after ejaculation the man's semen stays inside the condom and does not touch the body of the person he is having sex with. If the man's sexual partner usually has allergic symptoms to semen but does not have any when a condom is used, this may show that his partner's body is extra-sensitive to semen. A person can often get over a mild semen allergy by coming into contact with semen often. If the allergic reaction is very bad, the person should see a doctor, especially if she is a woman trying to get pregnant. In such cases, it may be necessary for the woman to have a baby through artificial insemination. This is a medical way of fertilizing a woman's ova using a man's sperm without the man and the woman having sexual intercourse.
Displaying semen in forms of popular culture such as art and movies has for a long time been taboo, that is, not generally accepted by society. However, since the late 20th century artists and moviemakers have done so more often.
The American photographer Andres Serrano sometimes takes photographs of body fluids and displays them as artworks. One example is Blood and Semen II (1990), which is a picture of blood and semen mixed together. Some people are shocked by such pictures and think it is wrong of him to make them, while others think that as an artist he should be free to create such works. Another of Serrano's pictures, Blood and Semen III, was featured on the cover of the 1996 music album Load by the American heavy metal band Metallica.
Apart from pornographic movies showing people having sex, semen is usually not shown in movies as many people think that doing so is obscene (not decent). However, some movies that have shown semen are the American comedy movies There's Something about Mary (1998), American Pie (1999), Scary Movie (2000) and Scary Movie 2 (2001). In the Spanish movie Y tu mamá también (And Your Mother Too, 2001), there is a scene where two high-school boys who are friends lie on diving boards over a swimming pool and masturbate (make themselves sexually excited). Semen is later shown floating on the water. Such movies are usually not thought to be suitable for children to watch.