Semen, also known as seminal fluid, is a bodily fluid that contains spermatozoa. Spermatozoa are secreted by the male gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. In placental mammals, semen also contains secretions from the male accessory glands and is discharged from the penis through the urethral orifice during ejaculation. 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 fluid is adapted to be discharged deep into the vagina, so the spermatozoa can pass into the uterus and form a zygote with an egg.
Semen is collected from animals for artificial insemination or cryoconservation of genetic material. Cryoconservation of animal genetic resources is a practice that calls for the collection of semen in efforts for conservation of a particular breed.
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.
Internal fertilization occurs inside the female's sexual organs after a male inseminates a female 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. [1] In marsupial and placental mammals, copulation occurs through the vagina. [2] [3] In macropods, semen coagulates and forms a mating plug in the vagina after copulation. [2] [4]
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. [5] The prostatic secretion, influenced by dihydrotestosterone, is a whitish (sometimes clear), thin fluid containing proteolytic enzymes, citric acid, acid phosphatase and lipids. [5] The bulbourethral glands secrete a clear secretion into the lumen of the urethra to lubricate it. [6]
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 principal 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 (c.f. sexual conflict) 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(s) | Approximate fraction | Description |
testes | 2–5% | Approximately 200 million 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 ejaculate. |
seminal vesicles | 65–75% | Amino acids, citrate, enzymes, flavins, fructose (2–5 mg per mL semen, [7] 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 μg/mL for healthy men. [8] 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. [9]
A 2005 review of the literature found that the average reported physical and chemical properties of human semen were as follows: [10]
Property | Per 100 mL | 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 (mg) | 62 | 2.11 |
Magnesium (mg) | 11 | 0.374 |
Potassium (mg) | 109 | 3.71 |
Protein (mg) | 5,040 | 171 |
Sodium (mg) | 300 | 10.2 |
Urea (mg) | 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. |
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. [11]
After ejaculation, the latter part of the ejaculated semen coagulates immediately, [12] forming globules, [13] while the earlier part of the ejaculate typically does not. [14] After a period typically ranging from 15 to 30 minutes, prostate-specific antigen present in the semen causes the decoagulation of the seminal coagulum. [15] It is postulated that the initial clotting helps keep the semen in the vagina, [12] while liquefaction frees the sperm to make their journey to the ova. [12]
A 2005 review found that the average reported viscosity of human semen in the literature was 3–7 centipoises (cP), or, equivalently, millipascal-seconds (mPa·s). [10]
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. [16]
The volume of semen ejaculate varies but is generally about 1 teaspoonful or less. A review of 30 studies concluded that the average was around 3.4 milliliters (mL), with some studies finding amounts as high as 5.0 mL or as low as 2.3 mL. [10] 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. [17]
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. [18] The IVT diluent is composed of several salts, sugars and antibacterial agents and gassed with CO2. [18]
Semen cryopreservation can be used for far longer storage durations. For human sperm, the longest reported successful storage with this method is 21 years. [19]
Semen can transmit many sexually transmitted infections and pathogens, including viruses like HIV [20] and Ebola. [21] Swallowing semen carries no additional risk other than those inherent in fellatio. This includes transmission risk for sexually transmitted infections such as human papillomavirus or herpes, especially for people with bleeding gums, gingivitis or open sores. [22] [23] Viruses in semen survive for a long time once outside the body. [24] [25] [26]
The presence of blood in semen or hematospermia may be undetectable (it can only 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.
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 treatments are often very successful. [27] [28]
Among numerous species in the animal kingdom, females may benefit from absorbing nutrients and proteins from seminal fluid for food, antiviral and antibacterial properties, and enhanced fertilisation. In humans, seminal fluid provides anti-viral activity towards herpes simplex virus and can transfer anti-microbial peptides cathelicidin and lactoferrin. In birds and mammals, mutalistic bacteria such as Lactobacillus have been detected in fluid transferral. [20]
Qigong and Chinese medicine place huge emphasis on a form of energy called 精 (pinyin: jīng, also a morpheme denoting "essence" or "spirit") [29] [30] – 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.
In Ayurveda, semen is said to be made from forty drops of blood. It is considered to be the end of the food digestion cycle. [31]
One of the key aspects of Hindu religion is abstinence called brahmacharya . It can be lifelong or during a specific period or on specific days. Brahmacharya attaches great importance to semen retention.
Many yogic texts also indicate the importance of semen retention and there are specific asanas and Bandhas for it like Mula Bandana and Aswini Mudra. [32]
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." [33] 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." [34]
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." [35]
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." [36] This may be explained by the belief of the Pythagoreans that "semen is a drop of the brain [τὸ δε σπέρμα εἶναι σταγόνα ἐγκέφαλου]." [37]
Greek Stoic philosophy conceived of the Logos spermatikos ("seminal word") as the principle of active reason that fecundated passive matter. [38] 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. [39]
The Christian Platonist Clement of Alexandria likened the Logos to physical blood [40] as the "substance of the soul", [41] and noted that some held "that the animal semen is substantially foam of its blood". [42] Clement reflected an early Christian view that "the seed ought not be wasted nor scattered thoughtlessly nor sown in a way it cannot grow." [43]
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. [44]
In ancient Greek religion as a whole, semen is considered a form of miasma, and ritual purification was to be practised after its discharge. [45]
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. The ancient Sumerians believed that semen was "a divine substance, endowed on humanity by Enki", the god of water. [46] : 28 [47] The semen of a god was believed to have magical generative powers. [46] : 49 In Sumerian mythology, when Enki's seed was planted in the ground, it caused the spontaneous growth of eight previously nonexistent plants. [46] : 49 [48] Enki was believed to have created the Tigris and Euphrates rivers by masturbating and ejaculating into their empty riverbeds. [46] : 32, 49 The Sumerians believed that rain was the semen of the sky-god An, [49] which fell from the heavens to inseminate his consort, the earth-goddess Ki, [49] causing her to give birth to all the plants of the earth. [49]
The orchid's twin bulbs were thought to resemble the testicles, which is the etymology of the disease orchiditis. There was an ancient Roman belief that the flower sprang from the spilled semen of copulating satyrs. [50]
In a number of mythologies around the world, semen is often considered analogous to breast milk. 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. [51]
Nancy Friday's book, Men in Love – Men's Sexual Fantasies: The Triumph of Love over Rage (1982), suggests that swallowing semen is high on a man's intimacy scale. [52]
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". [53]
The Borborites, also known as the Phibionites, were an early Christian Gnostic sect during the late fourth century AD whose alleged practices involving sacred semen are described by the early Christian heretic-hunter Epiphanius of Salamis in his Panarion . [54] [55] [56] [57] Epiphanius claims that the Borborites had a sacred text called the Greater Questions of Mary, which contained an episode in which, during a post-resurrection appearance, Jesus took Mary Magdalene to the top of a mountain, where he pulled a woman out of his side and engaged in sexual intercourse with her. [55] [54] [57] Then, upon ejaculating, Jesus drank his own semen and told Mary, "Thus we must do, that we may live." [55] [54] [57] Upon hearing this, Mary instantly fainted, to which Jesus responded by helping her up and telling her, "O thou of little faith, wherefore didst thou doubt?" [55] [57] This story was supposedly the basis for the Borborite Eucharist ritual, in which they allegedly engaged in orgies and drank semen and menstrual blood as the "body and blood of Christ" respectively. [54] [57] [55] Bart D. Ehrman, a scholar of early Christianity, casts doubt on the accuracy of Epiphanius's summary, commenting that "the details of Epiphanius's description sound very much like what you can find in the ancient rumor mill about secret societies in the ancient world". [54]
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. [58] [59] This act may also be associated with the culturally active homosexuality throughout these and other tribes. [60]
Semen ingestion has had central importance in some cultures around the world. In Baruya culture, there is a secret ritual in which boys give fellatio to young males and drink their semen, to "re-engender themselves before marriage". [61]
There are several sexual practices involving the ingestion of semen, which may be done with one or more partners. Practices involving the oral intake of semen include:
A huge variety of euphemisms and dysphemisms have been invented to describe semen. For a list of terms, see sexual slang .
Slang terms for semen include cum, jizz, spunk (primarily British English), spooge and/or splooge, load, nut, seed, and love juice. [73] [74] The term cum can also refer to an orgasm (when used as a verb rather than as a noun), while load is derived from the phrase blowing a load, referring to an ejaculation. The term nut originally refers to the testicles, but can be used to refer to both semen and ejaculation.
Coitus interruptus, also known as withdrawal, pulling out or the pull-out method, is an act of birth control during penetrative sexual intercourse, whereby the penis is withdrawn from a vagina prior to ejaculation so that the ejaculate (semen) may be directed away in an effort to avoid insemination.
A spermatozoon is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote.
Pre-ejaculate is a clear, colorless, viscous fluid that is emitted from the urethra of the penis during sexual arousal and in general during sexual activity. It is similar in composition to semen but has distinct chemical differences. The presence of sperm in the fluid is variable from low to absent. Pre-ejaculate functions as a lubricant and an acid neutralizer.
Retrograde ejaculation occurs when semen which would be ejaculated via the urethra is redirected to the urinary bladder. Normally, the sphincter of the bladder contracts before ejaculation, inhibiting urination and preventing a reflux of semen into the bladder. The semen is forced to exit via the urethra, the path of least resistance. When the bladder sphincter does not function properly, retrograde ejaculation may occur. It can also be induced deliberately by a male as a primitive form of male birth control or as part of certain alternative medicine practices. The retrograde-ejaculated semen is excreted from the bladder during the next urination.
The seminal vesicles are a pair of convoluted tubular accessory glands that lie behind the urinary bladder of male mammals. They secrete fluid that partly composes the semen.
A cum shot is the depiction of human ejaculation, especially onto another person. The term is usually applied to depictions occurring in pornographic films, photographs, and magazines. Unlike ejaculation in non-pornographic sex, cum shots typically involve ejaculation outside the receiver's body, allowing the viewer to see the ejaculation in progress. Facial cum shots are regularly portrayed in pornographic films and videos, often as a way to close a scene. Cum shots may also depict ejaculation onto another performer's body, such as on the genitals, buttocks, chest or tongue.
The epididymis is an elongated tubular structure attached to the posterior side of each one of the two male reproductive glands, the testicles. It is a single, narrow, tightly coiled tube in adult humans, 6 to 7 centimetres in length; uncoiled the tube would be approximately 6 m long. It connects the testicle to the vas deferens in the male reproductive system. The epididymis serves as an interconnection between the multiple efferent ducts at the rear of a testicle (proximally), and the vas deferens (distally). Its primary function is the storage, maturation and transport of sperm cells.
The ejaculatory ducts are paired structures in the male reproductive system. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate, and open into the urethra above the seminal colliculus. During ejaculation, semen passes through the prostate gland, enters the urethra and exits the body via the urinary meatus.
A facial is a sexual activity in which a man ejaculates semen onto the face of one or more sexual partners. A facial is a form of non-penetrative sex, though it is generally performed after some other means of sexual stimulation, such as vaginal sex, anal sex, oral sex, manual sex or masturbation. Facials are regularly portrayed in pornographic films and videos, often as a way to close a scene.
Capacitation is the penultimate step in the maturation of mammalian spermatozoa and is required to render them competent to fertilize an oocyte. This step is a biochemical event; the sperm move normally and look mature prior to capacitation. In vivo, capacitation occurs after ejaculation, when the spermatozoa leave the vagina and enter the upper female reproductive tract. The uterus aids in the steps of capacitation by secreting sterol-binding albumin, lipoproteins, and proteolytic and glycosidasic enzymes such as heparin.
The male reproductive system consists of a number of sex organs that play a role in the process of human reproduction. These organs are located on the outside of the body, and within the pelvis.
Aspermia is the complete lack of semen with ejaculation. It is associated with infertility.
Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction. Animals produce motile sperm with a tail known as a flagellum, which are known as spermatozoa, while some red algae and fungi produce non-motile sperm cells, known as spermatia. Flowering plants contain non-motile sperm inside pollen, while some more basal plants like ferns and some gymnosperms have motile sperm.
Hypospermia is a condition in which a man has an unusually low ejaculate volume, less than 1.5 mL. It is the opposite of hyperspermia, which is a semen volume of more than 5.5 mL. It should not be confused with oligospermia, which means low sperm count. Normal ejaculate when a man is not drained from prior sex and is suitably aroused is around 1.5–6 mL, although this varies greatly with mood, physical condition, and sexual activity. Of this, around 1% by volume is sperm cells. The U.S.-based National Institutes of Health defines hypospermia as a semen volume lower than 2 mL on at least two semen analyses.
Human reproduction is sexual reproduction that results in human fertilization to produce a human offspring. It typically involves sexual intercourse between a sexually mature human male and female. During sexual intercourse, the interaction between the male and female reproductive systems results in fertilization of the ovum by the sperm to form a zygote. While normal cells contain 46 chromosomes, gamete cells only contain 23 single chromosomes, and it is when these two cells merge into one zygote cell that genetic recombination occurs and the new zygote contains 23 chromosomes from each parent, giving it 46 chromosomes. The zygote then undergoes a defined development process that is known as human embryogenesis, and this starts the typical 9-month gestation period that is followed by childbirth. The fertilization of the ovum may be achieved by artificial insemination methods, which do not involve sexual intercourse. Assisted reproductive technology also exists.
A semen analysis, also called seminogram or spermiogram, evaluates certain characteristics of a male's semen and the sperm contained therein. It is done to help evaluate male fertility, whether for those seeking pregnancy or verifying the success of vasectomy. Depending on the measurement method, just a few characteristics may be evaluated or many characteristics may be evaluated. Collection techniques and precise measurement method may influence results. The assay is also referred to as ejaculate analysis, human sperm assay (HSA), sperm function test, and sperm assay.
Semen quality is a measure of male fertility, a measure of the ability of sperm in semen to accomplish fertilization. Semen quality involves both sperm quantity and quality. Semen quality is a major factor for fertility.
In human anatomy, the penis is an external male sex organ that serves as a passage for excretion of urine and ejaculation of semen. The main parts are the root, body, the epithelium of the penis including the shaft skin, and the foreskin covering the glans. The body of the penis is made up of three columns of tissue: two corpora cavernosa on the dorsal side and corpus spongiosum between them on the ventral side. The urethra passes through the prostate gland, where it is joined by the ejaculatory ducts, and then through the penis. The urethra goes across the corpus spongiosum and ends at the tip of the glans as the opening, the urinary meatus.
Ejaculation is the discharge of semen through the urethra in men. It is normally linked with orgasm, which involves involuntary contractions of the pelvic floor. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. Ejaculation can occur spontaneously during sleep, and is a normal part of human sexual development. In rare cases, ejaculation occurs because of prostatic disease. Anejaculation is the condition of being unable to ejaculate. Ejaculation is normally intensely pleasurable for men; dysejaculation is an ejaculation that is painful or uncomfortable. Retrograde ejaculation is the backward flow of semen into the bladder rather than out of the urethra.
Antisperm antibodies (ASA) are antibodies produced against sperm antigens.
Ehrman to you as apostles.