semen semen semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. it is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. semen is produced and originates from the seminal vesicle, which is located in the pelvis. the process that results in the discharge of semen from the urethral orifice is called 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. not to be confused with sperm. spermatozoa, in this case human, are a primary component in normal semen, and the agents of fertilization of female ova. semen is also a form of genetic material. in animals, semen has been collected for cryoconservation. cryoconservation of animal genetic resources is a practice that calls for the collection of genetic material in efforts for conservation of a particular breed. physiology 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 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 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 fractiondescription testes2–5%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 vesicles65–75%amino acids, citrate, enzymes, flavins, fructose (2–5 mg per ml semen, 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. prostate25–30%acid phosphatase, citric acid, fibrinolysin, prostate specific antigen, proteolytic enzymes, zinc. (the zinc level is about 135±40 μg/ml for healthy men. 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. a 2005 review of the literature found that the average reported physical and chemical properties of human semen were as follows: property per 100 ml in average volume (3.4 ml) calcium (mg)27.60.938 chloride (mg)1424.83 citrate (mg)52818.0 fructose (mg)2729.25 glucose (mg)1023.47 lactic acid (mg)622.11 magnesium (mg)110.374 potassium (mg)1093.71 protein (mg)5,040171 sodium (mg)30010.2 urea (mg)451.53 zinc (mg)16.50.561 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 human semen in a petri dish 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. after ejaculation, the latter part of the ejaculated semen coagulates immediately, forming globules, while the earlier part of the ejaculate typically does not. after a period typically ranging from 15 to 30 minutes, prostate-specific antigen present in the semen causes the decoagulation of the seminal coagulum. it is postulated that the initial clotting helps keep the semen in the vagina, while liquefaction frees the sperm to make their journey to the ova. 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). quality main article: semen qualitysemen 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 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. 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. 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. the ivt diluent is composed of several salts, sugars and antibacterial agents and gassed with co2. semen cryopreservation can be used for far longer storage durations. for human sperm, the longest reported successful storage with this method is 21 years. health disease transmission semen can transmit many sexually transmitted diseases and pathogens, including viruses like hiv and ebola. swallowing semen carries no additional risk other than those inherent in fellatio. this includes transmission risk for sexually transmitted diseases such as human papillomavirus or herpes, especially for people with bleeding gums, gingivitis or open sores. viruses in semen survive for a long time once outside the body. bloodiness main article: hematospermia 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. 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 treatments are often very successful. benefits to females females may benefit from absorbing seminal fluid. such benefits include male insects transferring nutrients to females via their ejaculate; in both humans and bovines, the fluid has antiviral and antibacterial properties; and useful bacteria such as lactobacillus have been detected in fluid transferred from birds and mammals. society and culture qigong 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 referents. indian philosophy 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. 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. 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." 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 in sexual activity at too early an age ... 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