Semen

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For other uses, see Semen (disambiguation).
Spermatozoa, in this case human, are a primary component in normal semen, and the agents of fertilization of the female ova

Semen, also known as seminal fluid, is an organic fluid that may contain 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".

Semen is produced and originates from the seminal vesicle, which is located in the pelvis. The process that results in the discharge of semen is called ejaculation.

Physiological aspects

Internal and external fertilization

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 most vertebrates, including 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.

Composition of human semen

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.[1] The prostatic secretion, influenced by dihydrotestosterone, is a whitish (sometimes clear), thin fluid containing proteolytic enzymes, citric acid, acid phosphatase and lipids.[1] The bulbourethral glands secrete a clear secretion into the lumen of the urethra to lubricate it.[2]

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 ductal fluid 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.

Seminal plasma of humans contains a complex range of organic and inorganic constituents.

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 and buffer 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:

Gland Approximate % Description
testes 2–5% Approximately 200- to 500-million spermatozoa (also called sperm or spermatozoans), produced in the testes, are released per ejaculation. If a man has undergone a vasectomy, he will have no sperm in the ejaculation.
seminal vesicle 65–75% amino acids, citrate, enzymes, flavins, fructose (2–5 mg per mL semen,[3] 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 (the zinc level is about 135±40 micrograms/ml for healthy men.[4] 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 20×106 spermatozoa/ml or more, sperm count of 40×106 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.[5]

A 2005 review of the literature found that the average reported physical and chemical properties of human semen were as follows:[6]

Property Per 100mL In average volume (3.4 mL)
Calcium (mg) 27.6 0.938
Chloride (mg) 142 4.83
Citrate (mg) 528 18.0
Fructose (mg) 272 9.25
Glucose (mg) 102 3.47
Lactic acid (g) 62 2.11
Magnesium (mg) 11 0.374
Potassium (mg) 109 3.71
Protein (g) 5.04 0.171
Sodium (mg) 300 10.2
Urea (g) 45 1.53
Zinc (mg) 16.5 0.561
Buffering capacity (β) 25
Osmolarity (mOsm) 354
pH 7.7
Viscosity (cP) 3–7
Volume (mL) 3.4
Values for average volume have been calculated and rounded to three significant figures. All other values are those given in the review.

Appearance and consistency of human semen

Semen is typically translucent with white, grey or even yellowish tint. 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 the symptom persists.[7]

After ejaculation, the latter part of the ejaculated semen coagulates immediately,[8] forming globules,[9] while the earlier part of the ejaculate typically does not.[10] After a period typically ranging from 15 – 30 minutes, prostate-specific antigen present in the semen causes the decoagulation of the seminal coagulum.[11] It is postulated that the initial clotting helps keep the semen in the vagina,[8] while liquefaction frees the sperm to make their journey to the ova.[8]

A 2005 review found that the average reported viscosity of human semen in the literature was 3–7 cP.[6]

Semen quality

Main article: Semen quality

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.

Quantity

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.[6] 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.[12]

Increasing semen volume

Some dietary supplements have been marketed with claims to increase seminal volume. Like other supplements, including so-called herbal viagra, these are not approved or regulated by the Food and Drug Administration (as licensed medications would be), and none of the claims have been scientifically verified. Similar claims are made about traditional aphrodisiac foods, with an equal lack of verification.

Semen storage

Semen can be stored in diluents such as the Illini Variable Temperature (IVT) diluent, which have been reported to be able to preserve high fertility of semen for over seven days.[13] The IVT diluent is composed of several salts, sugars and antibacterial agents and gassed with CO2.[13]

Semen cryopreservation can be used for far longer storage durations. For human sperm, the longest reported successful storage with this method is 21 years.[14]

Health effects

In addition to its central role in reproduction, some studies have made claims that semen may have certain beneficial effects on human health:

  • Antidepressant: One study suggested that vaginal absorption of semen could act as an antidepressant; the study compared two groups of women, one of which used condoms and the other did not.[15][16]
  • Cancer prevention: Studies suggested that seminal plasma might reduce breast cancer by "not less than 50 percent."[17][18] This effect is attributed to its glycoprotein and selenium content, with apoptosis being induced by TGF-Beta. A related urban legend parodied these findings and claimed that performing fellatio at least three times a week reduced the risk of breast cancer.[19]
  • Preeclampsia prevention: It has been hypothesized that substances in semen condition a mother's immune system to accept the "foreign" proteins found in sperm as well as the resulting fetus and placenta, keeping blood pressure low and thereby reducing the risk of preeclampsia. A study shows that oral sex and swallowing semen may help make a woman's pregnancy safer and more successful, because she is absorbing her partner's antigens.[20]
  • Increased libido: Another hypothesis has emerged that absorption of the testosterone contained in semen through a woman's vaginal walls during sexual intercourse (or even through the act of swallowing semen) may increase her sex drive.

Other studies claim adversarial effects:

Semen and transmission of disease

Semen can be the vehicle for many sexually transmitted diseases, including HIV, the virus that causes AIDS.

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.[22]

Semen contains many proteins with potent antimicrobial activity against bacteria, fungi and virus. But none of these proteins are active against Neisseria gonorrhoeae, a common cause of sexually transmitted disease.

Blood in the semen (hematospermia)

Main article: Hematospermia

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 or prostate.

It usually clears up without treatment, or with antibiotics, but if persistent further semen analysis and other urogenital system tests might be needed to find out the cause.

Semen allergy

In rare circumstances, humans can develop an allergy to semen, called human seminal plasma sensitivity. It appears as a typical localized or systemic allergic response upon contact with seminal fluid. There is no one protein in semen responsible for the reaction. Symptoms can appear after first intercourse or after subsequent intercourse. A semen allergy can be distinguished from a latex allergy by determining if the symptoms disappear with use of a condom. Desensitization treatment is very often successful.[23][24]

Psychological aspects

The authors of a 2002 study claimed that semen acts as an antidepressant in women, so that women physically exposed to semen are less likely to suffer from depression. The authors suggested that the alleged 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). These conclusions were based on a scientific survey of 293 college women which found that women who rarely or never used condoms had fewer symptoms of depression compared to women who always or nearly always used them. 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 they might have a chemical dependency on semen, which could create a "rebound effect". The effect of semen on a male sexual partner (as the receiver of semen) is not known.[16][25][26]

Cultural aspects

Qigong

Qigong and Chinese medicine place huge emphasis on a form of energy called 精 (pinyin: jīng, also a morpheme denoting "essence" or "spirit")[27][28] – 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 referents.

Greek philosophy

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."[29] 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."[30]

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."[31]

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."[32] This may be explained by the belief of the Pythagoreans that "semen is a drop of the brain [τὸ δε σπέρμα εἶναι σταγόνα ἐγκέφαλου]."[33]

Greek Stoic philosophy conceived of the Logos spermatikos ("seminal word") as the principle of active reason that fecundated passive matter.[34] 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.[35]

The Christian Platonist Clement of Alexandria likened the Logos to physical blood[36] as the "substance of the soul,"[37] and noted that some held "that the animal semen is substantially foam of its blood".[38] Clement reflected an early Christian view that "the seed ought not be wasted nor scattered thoughtlessly nor sown in a way it cannot grow."[39]

Women were believed to have their own version, which was stored in the womb and released during climax. Retention was believed to cause female hysteria.[40]

Sacred semen

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[citation needed] 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.[citation needed]

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.)

The orchid’s twin bulbs were thought to resemble the testicles, and there was an ancient Roman belief that the flower sprang from the spilled semen of copulating satyrs.

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.[41]

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.[42]

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).[citation needed]

Semen in espionage

Semen stain on carpet observed with and without ultraviolet light

When the British Secret Intelligence Service discovered that semen made a good invisible ink, Sir George Mansfield Smith-Cumming noted of his agents that "Every man (is) his own stylo".[43]

Semen ingestion

Some reasons for human ingestion of human or other semen are erotic gratification and physical and spiritual benefits.

Health risks

Swallowing semen carries no additional risk other than those inherent in fellatio. Fellatio does carry transmission risk for sexually transmitted diseases such as or human papillomavirus (HPV) or herpes, especially for people with bleeding gums, gingivitis or open sores.[44][45]

Even if semen is cold before the individual ingests it, viruses can stay active for a long period of time once outside the body.

Research has suggested that performing unprotected oral sex on a person infected with HPV might increase the risk of oral or throat cancer. The study found that 36% of the cancer patients had HPV compared to only 1% 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.[46]

Physical benefits

An average ejaculation (3.4 mL) contains trace amounts of many nutrients such as zinc, calcium and potassium, as well as vitamin B12. [47] The limited studies on the health benefits of semen ingestion are positive.

Some female infertility, preeclampsia and miscarriages are due to the inherent presence of antibodies that destroy the proteins or antigens in her sexual partner's semen. Having oral sex and swallowing the semen of the partner may help make the pregnancy safer and more successful as the woman is ingesting her partner's antigens.[48]

There has been no scientific research conducted into whether oral ingestion of semen has an antidepressive effect, however, semen does contain several mood-elevating compounds such as endorphins, estrone, prolactin, oxytocin, thyrotropin-releasing hormone, and serotonin. The noted beneficial effects of these hormones have thus far been studied with vaginal absorption only.[49][50]

Cultural practices

In some cultures, semen is considered to have special properties associated with masculinity. Several tribes of Papua New Guinea, including the Sambia and the Etoro, believe that semen promotes sexual maturation among the younger men of their tribe. To them, semen 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. Prepubescent and postpubescent males are required to engage in this practice.[51][52] This act may also be associated with the culturally active homosexuality throughout these and other tribes.[53]

Spiritual views

The church father Epiphanius records that the Borborites[54] and other libertine Gnostic sects[55] consumed semen as the Body of Christ. The Pistis Sophia[56] and Testimony of Truth[57] harshly condemn such practices.

In the modern St. Priapus Church, consumption of semen in the presence of others is a form of worship.[58][dubious ]

Sexual practices

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.

Euphemisms

A huge variety of euphemisms and dysphemisms have been invented to describe semen. For a complete list of terms, see sexual slang.

See also

References

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  2. ^ Guyton, Arthur C. (1991). Textbook of Medical Physiology (8th ed.). Philadelphia: W.B. Saunders. pp. 890–891. ISBN 0-7216-3994-1. 
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  19. ^ "Fellatio Breast Cancer Reduction".  Also at about.com Study: Fellatio May Significantly Decrease the Risk of Breast Cancer in Women
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  21. ^ Muller, M.; Sales, KJ; Katz, AA; Jabbour, HN (2006). "Seminal Plasma Promotes the Expression of Tumorigenic and Angiogenic Genes in Cervical Adenocarcinoma Cells via the E-Series Prostanoid 4 Receptor". Endocrinology 147 (7): 3356–65. doi:10.1210/en.2005-1429. PMID 16574793. 
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  26. ^ Raj Persaud (June 26, 2002). "Semen acts as an anti-depressant". New Scientist. 
  27. ^ Qigong Bible, Chapter #8, by Gary J. Clyman. Contribution To Clyman's Book by Frank Ranz, January 1989
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  31. ^ Aristotle; Richard Kraut (trans.) (1997). Politics. Oxford UP. p. 152. ISBN 978-0-19-875114-4. Retrieved November 9, 2013. 
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  35. ^ "And when she (intelligence) lives as a comely wife with comely Reason (Logos), that is with virtuous Reason, this self-same Reason himself undertakes the care of her, sowing, like a husband, the most excellent concepts in her." Philo, De Spec. Leg., § 7. Mead, G.R.S (1906). "Philo of Alexandria and the Hellenistic Theology". Thrice Greatest Hermes: Studies in Hellenistic Theosophy and Gnosis I. London and Benares: The Theosophical Publishing Society. p. 222. ISBN 0-87728-947-6. 
  36. ^ "And that the blood is the Word, is testified by the blood of Abel, the righteous interceding with God." Clement of Alexandria, The Paedagogus, 1, 47.
  37. ^ Cf. Leviticus 17:14; Clement of Alexandria, The Paedagogus, 1, 39.
  38. ^ Clement of Alexandria, The Paedagogus, 1, 48.
  39. ^ Clement of Alexandria, The Paedagogus, 2, 91. See also: Onan.
  40. ^ Roach, Mary (2009). Bonk : the curious coupling of science and sex. New York: W.W. Norton & Co. p. 214. ISBN 9780393334791. 
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  43. ^ The Independent review of The Quest for C: Mansfield Cumming and the founding of the British Secret Service by Alan Judd
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  47. ^ Swallowing Semen[full citation needed]
  48. ^ Koelman, CA; Coumans, AB; Nijman, HW; Doxiadis, II; Dekker, GA; Claas, FH (2000). "Correlation between oral sex and a low incidence of preeclampsia: A role for soluble HLA in seminal fluid?". Journal of reproductive immunology 46 (2): 155–66. doi:10.1016/S0165-0378(99)00062-5. PMID 10706945. 
  49. ^ Attention, Ladies: Semen Is An Antidepressant[full citation needed]
  50. ^ Bering, Jesse (September 22, 2010). "An Ode to the Many Evolved Virtues of Human Semen". Scientific American. 
  51. ^ Robert T. Francoeur, Raymond J. Noonan (2004) The Continuum Complete International Encyclopedia of Sexuality p.819
  52. ^ Semen Warriors Of New Guinea, Hank Hyena, September 16, 1999
  53. ^ Herdt, Gilbert (editor) (January 28, 1993). Ritualized Homosexuality in Melanesia. University of California Press. ISBN 0-520-08096-3. 
  54. ^ Epiphanius, Panarion, 26, 4.
  55. ^ I.e., the Simonians; Epiphanius, Panarion, 21, 4.
  56. ^ "We have heard that there are men on the earth who take the sperm of men and the flux of women, and mix them with lentils and eat them, saying, 'We believe in Esau and Jacob'" (386–387). Mead, G.R.S (1896). Pistis Sophia. London: The Theosophical Publishing Society. p. 390. ISBN 1-4179-1276-6. Retrieved November 9, 2013. 
  57. ^ Meyer, Marvin (2007). "The Testimony of Truth". The Nag Hammadi Scriptures. trans. Birger A. Pearson. Harper Collins. p. 624. ISBN 978-0-06-052378-7. 
  58. ^ J. Gordon Melton (1996, 5th ed.). Encyclopedia of American Religions (Detroit, Mich.: Gale) ISBN 0-8103-7714-4 p. 952.

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