Ejaculation is the discharge of

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. Sem ...

(the ''ejaculate''; normally containing sperm) from the male reproductory tract as a result of an

orgasm Orgasm (from Greek , ; "excitement, swelling") or sexual climax is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic, involuntary muscular contractions in the pelvic region chara ...

. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. In rare cases, ejaculation occurs because of

prostatic On either side of the urethral crest is a slightly depressed fossa, the prostatic sinus, the floor of which is perforated by numerous apertures, the orifices of the prostatic ducts from the lateral lobes of the prostate The prostate is bo ...

disease. Ejaculation may also occur spontaneously during

sleep Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...

nocturnal emission A nocturnal emission, informally known as a wet dream, sex dream, nightfall or sleep orgasm, is a spontaneous orgasm during sleep that includes ejaculation for a male, or vaginal wetness or an orgasm (or both) for a female. Nocturnal emissions ...

or "wet dream"). ''

Anejaculation Anejaculation is the pathological inability to ejaculate despite an erection in males, with (''orgasmic'') or without (''anorgasmic'') orgasm. Causes It can depend on one or more of several causes, including: * Sexual inhibition * Pharmacologic ...

'' is the condition of being unable to ejaculate. Ejaculation is usually very pleasurable for men; '' dysejaculation'' is an ejaculation that is painful or uncomfortable.

Retrograde ejaculation 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, sealing the bladder which besides inhibiting the relea ...

is the condition where semen travels backwards into the bladder rather than out the

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...

Phases

Stimulation

A usual precursor to ejaculation is the sexual arousal of the male, leading to the erection of the

penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males d ...

, though not every arousal nor erection leads to ejaculation. Penile sexual stimulation during masturbation or vaginal,

anal Anal may refer to: Related to the anus *Related to the anus of animals: ** Anal fin, in fish anatomy ** Anal vein, in insect anatomy ** Anal scale, in reptile anatomy *Related to the human anus: ** Anal sex, a type of sexual activity involving s ...

, oral, or non-penetrative sexual activity may provide the necessary stimulus for a man to achieve

and ejaculation. With regard to

intravaginal ejaculation latency time Intravaginal ejaculation latency time (IELT) is the time it takes to ejaculate during vaginal penetration. Average IELT varies between people and tends to decrease with age. Some medications such as selective serotonin reuptake inhibitors (SSRIs) ...

, men typically reach orgasm 5–7 minutes after the start of penile-vaginal intercourse, taking into account their desires and those of their partners, but 10 minutes is also a common intravaginal ejaculation latency time. A prolonged stimulation either through

foreplay Foreplay is a set of emotionally and physically intimate acts between one or more people meant to create sexual arousal and desire for sexual activity. Although foreplay is typically understood as physical sexual activity, nonphysical activiti ...

(kissing, petting and direct stimulation of erogenous zones before penetration during intercourse) or stroking (during masturbation) leads to an adequate amount of arousal and production of pre-ejaculatory fluid. While the presence of sperm in pre-ejaculatory fluid is thought to be rare, sperm from an earlier ejaculation, still present in the

, may be picked up by pre-ejaculatory fluid. In addition, infectious agents (including

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

) can often be present in pre-ejaculate. Premature ejaculation is when ejaculation occurs before the desired time. If a man is unable to ejaculate in a timely manner after prolonged sexual stimulation, in spite of his desire to do so, it is called delayed ejaculation or anorgasmia. An orgasm that is not accompanied by ejaculation is known as a

dry orgasm Orgasm (from Greek , ; "excitement, swelling") or sexual climax is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic, involuntary muscular contractions in the pelvic region chara ...

. When a man has achieved a sufficient stimulation and orgasm, ejaculation begins. At that point, under the control of the sympathetic nervous system,

containing sperm is produced (emission). The semen is ejected through the

with rhythmic contractions. These rhythmic contractions are part of the male orgasm. They are generated by the bulbospongiosus and pubococcygeus muscles under the control of a spinal reflex at the level of the spinal nerves S2–4 via the

pudendal nerve The pudendal nerve is the main nerve of the perineum. It carries sensation from the external genitalia of both sexes and the skin around the anus and perineum, as well as the motor supply to various pelvic muscles, including the male or fem ...

. The typical male orgasm lasts several seconds. After the start of orgasm, pulses of semen begin to flow from the urethra, reach a peak discharge and then diminish in flow. The typical orgasm consists of 10 to 15 contractions, although the man is unlikely to be consciously aware of that many. Once the first contraction has taken place, ejaculation will continue to completion as an involuntary process. At this stage, ejaculation cannot be stopped. The rate of contractions gradually slows during the orgasm. Initial contractions occur at an average interval of 0.6 seconds with an increasing increment of 0.1 seconds per contraction. Contractions of most men proceed at regular rhythmic intervals for the duration of the orgasm. Many men also experience additional irregular contractions at the conclusion of the orgasm. Ejaculation usually begins during the first or second contraction of orgasm. For most men, the first ejection of semen occurs during the second contraction, while the second is typically the largest expelling 40% or more of total semen discharge. After this peak, the magnitude of semen the penis emits diminishes as the contractions begin to lessen in intensity. The muscle contractions of the orgasm can continue after ejaculation with no additional semen discharge occurring. A small sample study of seven men showed an average of 7 spurts of semen followed by an average of 10 more contractions with no semen expelled. This study also found a high correlation between number of spurts of semen and total ejaculate volume, i.e., larger semen volumes resulted from additional pulses of semen rather than larger individual spurts.

Alfred Kinsey Alfred Charles Kinsey (; June 23, 1894 – August 25, 1956) was an American sexologist, biologist, and professor of entomology and zoology who, in 1947, founded the Institute for Sex Research at Indiana University, now known as the Kinsey Insti ...

measured the distance of ejaculation, in "some hundreds" of men. In three-quarters of men tested, ejaculate "is propelled with so little force that the liquid is not carried more than a minute distance beyond the tip of the penis." In contrast to those test subjects, Kinsey noted "In other males the semen may be propelled from a matter of some inches to a foot or two, or even as far as five or six and (rarely) eight feet".

Masters and Johnson The Masters and Johnson research team, composed of William H. Masters and Virginia E. Johnson, pioneered research into the nature of human sexual response and the diagnosis and treatment of sexual disorders and dysfunctions from 1957 until the 1 ...

report ejaculation distance to be no greater than . During the series of contractions that accompany ejaculation, semen is propelled from the urethra at , close to .

Refractory period

Most men experience a refractory period immediately following an orgasm, during which time they are unable to achieve another erection, and a longer period again before they are capable of achieving another ejaculation. During this time a male feels a deep and often pleasurable sense of relaxation, usually felt in the groin and thighs. The duration of the refractory period varies considerably, even for a given individual. Age affects the recovery time, with younger men typically recovering faster than older men, though not universally so. Whereas some men may have refractory periods of 15 minutes or more, some men are able to experience sexual arousal immediately after ejaculation. A short recovery period may allow partners to continue sexual play relatively uninterrupted by ejaculation. Some men may experience their penis becoming hypersensitive to stimulation after ejaculation, which can make sexual stimulation unpleasant even while they may be sexually aroused. There are men who are able to achieve multiple orgasms, with or without the typical sequence of ejaculation and refractory period. Some of those men report not noticing refractory periods, or are able to maintain erection by "sustaining sexual activity with a full erection until they passed their refractory time for orgasm when they proceeded to have a second or third orgasm".

Volume

The force and amount of semen that will be ejected during an ejaculation will vary widely between men and may contain between 0.1 and 10 milliliters (by way of comparison, note that a

teaspoon A teaspoon (tsp.) is an item of cutlery. It is a small spoon that can be used to stir a cup of tea or coffee, or as a tool for measuring volume. The size of teaspoons ranges from about . For cooking purposes and dosing of medicine, a teaspoonf ...

is 5 ml and a tablespoon holds 15 ml). Adult semen volume is affected by the time that has passed since the previous ejaculation; larger semen volumes are seen with greater durations of abstinence. The duration of the stimulation leading up to the ejaculation can affect the volume. Abnormally low semen volume is known as

hypospermia Hypospermia is a condition in which a man has an unusually low ejaculate (or semen) 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 mea ...

and abnormally high semen volume is known as

hyperspermia In medicine hyperspermia is a condition where a male has an abnormally large amount of semen or ejaculate volume and is generally defined when the ejaculate is above 5.5 ml.Padubidri; Daftary (2011). Shaw's Textbook of Gynaecology, 15e. p. 204. I ...

. One of the possible underlying causes of low volume or complete lack of semen is

ejaculatory duct obstruction Ejaculatory duct obstruction (EDO) is a pathological condition which is characterized by the obstruction of one or both ejaculatory ducts. Thus, the efflux of (most constituents of) semen is not possible. It can be congenital or acquired. It is ...

. It is normal for the amount of semen to diminish with age.

Quality

The number of sperm in an ejaculation also varies widely, depending on many factors, including the time since the last ejaculation, age, stress levels, and

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...

. Greater lengths of sexual stimulation immediately preceding ejaculation can result in higher concentrations of sperm. An unusually low sperm count, not the same as low semen volume, is known as

oligospermia Terms oligospermia, oligozoospermia, and low sperm count refer to semen with a low concentration of sperm and is a common finding in male infertility. Often semen with a decreased sperm concentration may also show significant abnormalities in spe ...

, and the absence of any sperm from the semen is termed azoospermia.

Development

During puberty

The first ejaculation in males often occurs about 12 months after the onset of

puberty Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a bo ...

, generally through masturbation or

(wet dreams). This first

volume is small. The typical ejaculation over the following three months produces less than 1 ml of semen. The semen produced during early puberty is also typically clear. After ejaculation this early semen remains jellylike and, unlike semen from mature males, fails to liquefy. A summary of semen development is shown in Table 1. Most first ejaculations (90%) lack sperm. Of the few early ejaculations that do contain sperm, the majority of sperm (97%) lack motion. The remaining sperm (3%) have abnormal motion. As the male proceeds through puberty, the semen develops mature characteristics with increasing quantities of normal sperm. Semen produced 12 to 14 months after the first ejaculation liquefies after a short period of time. Within 24 months of the first ejaculation, the semen volume and the quantity and characteristics of the sperm match that of adult male semen. Ejaculate is jellylike and fails to liquefy.
Most samples liquefy. Some remain jellylike.
Ejaculate liquefies within an hour.

Control from the central nervous system

There is a central pattern generator in the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

, made up of groups of

spinal interneuron A spinal interneuron, found in the spinal cord, relays signals between (afferent) sensory neurons, and (efferent) motor neurons. Different classes of spinal interneurons are involved in the process of sensory-motor integration. Most interneuron ...

s, that is involved in the rhythmic response of ejaculation. This is known as the ''spinal generator for ejaculation''. To map the neuronal activation of the brain during the ejaculatory response, researchers have studied the expression of c-Fos, a

proto-oncogene An oncogene is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels.

expressed in neurons in response to stimulation by hormones and neurotransmitters. Expression of c-Fos in the following areas has been observed: * medial

preoptic area The preoptic area is a region of the hypothalamus. MeSH classifies it as part of the anterior hypothalamus. TA lists four nuclei in this region, (medial, median, lateral, and periventricular). Functions The preoptic area is responsible for ther ...

(MPOA) * lateral septum, bed nucleus of the stria terminalis * paraventricular nucleus of hypothalamus (PVN) *

ventromedial nucleus of the hypothalamus The ventromedial nucleus of the hypothalamus (VMN, also sometimes referred to as the ventromedial hypothalamus, VMH) is a nucleus of the hypothalamus. "The ventromedial hypothalamus (VMH) is a distinct morphological nucleus involved in terminatin ...

, medial

amygdala The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verte ...

* ventral premammillary nuclei * ventral tegmental area * central tegmental field * mesencephalic central gray * peripeduncular nuclei * parvocellular subparafascicular nucleus (SPF) within the posterior

thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...

Hands-free ejaculation

Although uncommon, some men can achieve ejaculations during masturbation without any manual stimulation. Such men usually do it by tensing and flexing their abdominal and buttocks muscles along with vigorous fantasising. Others may do it by relaxing the area around the penis, which may result in harder erections especially when hyperaroused.

Perineum pressing and retrograde ejaculation

Perineum The perineum in humans is the space between the anus and scrotum in the male, or between the anus and the vulva in the female. The perineum is the region of the body between the pubic symphysis (pubic arch) and the coccyx (tail bone), includi ...

pressing results in an ejaculation which is purposefully held back by pressing on either the perineum or the urethra to force the seminal fluid to remain inside. In such a scenario, the seminal fluid stays inside the body and goes to the bladder. Some people do this to avoid making a mess by keeping all the semen inside. As a medical condition, it is called

retrograde ejaculation 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, sealing the bladder which besides inhibiting the relea ...

Health issues

For most men, no detrimental health effects have been determined from ejaculation itself or from frequent ejaculations, though sexual activity in general can have health or psychological consequences. A small fraction of men have a disease called postorgasmic illness syndrome (POIS), which causes severe muscle pain throughout the body and other symptoms immediately following ejaculation. The symptoms last for up to a week. Some doctors speculate that the frequency of POIS "in the population may be greater than has been reported in the academic literature", and that many POIS sufferers are undiagnosed. It is not clear whether frequent ejaculation has any effect on the risk of prostate cancer. Two large studies examining the issue were "Ejaculation Frequency and Subsequent Risk of Prostate Cancer" and "Sexual Factors and Prostate Cancer". These suggest that frequent ejaculation after puberty offers some reduction of the risk of prostate cancer. The US study involving 29,342 US men aged 46 to 81 years suggested that "high ejaculation frequency was related to decreased risk of total prostate cancer". An Australian study involving 1,079 men with prostate cancer and 1,259 healthy men found that "there is evidence that the more frequently men ejaculate between the ages of 20 and 50, the less likely they are to develop prostate cancer":

Other animals

In mammals and birds, multiple ejaculation is commonplace. During copulation, the two sides of a

short-beaked echidna The short-beaked echidna (''Tachyglossus aculeatus''), also called the short-nosed echidna, is one of four living species of echidna and the only member of the genus ''Tachyglossus''. It is covered in fur and spines and has a distinctive snout ...

's penis are used sequentially. Alternating between the two sides allows for persistent stimulation to induce ejaculation without impeding the refractory period. In stallions, ejaculation is accompanied by a motion of the tail known as "tail flagging". When a male

wolf The wolf (''Canis lupus''; : wolves), also known as the gray wolf or grey wolf, is a large canine native to Eurasia and North America. More than thirty subspecies of ''Canis lupus'' have been recognized, and gray wolves, as popularly un ...

ejaculates, his final

pelvic thrust The pelvic thrust is the thrusting motion of the pelvic region, which is used for a variety of activities, such as dance or sexual activity. Sexual activity The pelvic thrust is used during copulation by many species of mammals, including hum ...

may be slightly prolonged. A male rhesus monkey usually ejaculates less than 15 seconds after sexual penetration. The first report and footage of spontaneous ejaculation in an aquatic mammal was recorded in a wild Indo-Pacific bottlenose dolphin near

Mikura Island is a volcanic Japanese island in the Pacific Ocean. Nussbaum, Louis-Frédéric. (2005)"''Izu Shotō'',"''Japan Encyclopedia,'' p. 412. The island is administered by Tōkyō Metropolis and is located approximately south of Tokyo and sout ...

, Japan, in 2012. In horses, sheep, and cattle, ejaculation occurs within a few seconds, but in

boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species is ...

s, it can last for five to thirty minutes. Ejaculation in boars is stimulated when the spiral-shaped penis interlocks with the female's cervix. A mature boar can produce of semen during one ejaculation. In llamas and alpacas, ejaculation occurs continuously during copulation. The semen of male dogs is ejaculated in three separate phases. The last phase of a male canine’s ejaculation occurs during the copulatory tie, and contains mostly prostatic fluid.