question: What causes the penis to stop growing?
comment: But wait. How has no one simply said, "hormones?" Hormones told my boobs to stop growing. I'm guessing they tell a dude's penis when it's done as well. Granted, there is a *huge* age range wherein this can happen, but it is the simplest biological answer. If you're still a teenager, I'll tell you this. 15:1, college penises were bigger than high school penises in my experience. If you're 18 or younger, you may not be done yet. (I can also tell you it *actually* doesn't matter anyhow, but considering I may be taking to a minor, Imma stop right there.) But yeah- hormones, and various growth-related parts of your brain. That's the simple answer.
passages: In the dog whelk, the growth of a penis in imposex females gradually blocks the oviduct, although ovule production continues. An imposex female dog whelk passes through several stages of penis growth before it becomes unable to maintain a constant production of ovules. Later stages of imposex lead to sterility and the premature death of the females of reproductive age, which can adversely affect the entire population.
  
  Section::::Biomonitoring.
   Many men with Venogenic Erectile Dysfunction start having trouble with their erections from a young age. Common complaints include a chronic soft erection insufficient for sexual intercourse, position-dependent erectile rigidity, difficulty achieving erections, difficulty maintaining erections without constant manual stimulation, loss of penile length and girth, and a soft glans of the penis during erection that is not fully engorged.
   Section::::Development.:Growth in puberty.
  
  On entering puberty, the penis, scrotum and testicles will enlarge toward maturity. During the process, pubic hair grows above and around the penis. A large-scale study assessing penis size in thousands of 17- to 19-year-old males found no difference in average penis size between 17-year-olds and 19-year-olds. From this, it can be concluded that penile growth is typically complete not later than age 17, and possibly earlier.
  
  Section::::Physiological functions.
  
  Section::::Physiological functions.:Urination.
   The length of the flaccid penis does not necessarily correspond to the length of the penis when it becomes erect; some smaller flaccid penises grow much longer, while some larger flaccid penises grow comparatively less.
  
  Generally, the size of an erect penis is fixed throughout post-pubescent life. Its size may be increased by surgery, although penile enlargement is controversial, and a majority of men were "not satisfied" with the results, according to one study.
   Section::::Treatment.:Surgery.
  
  Often, as a last resort if other treatments have failed, the most common procedure is prosthetic implants which involves the insertion of artificial rods into the penis. Some sources show that vascular reconstructive surgeries are viable options for some people.
  
  Section::::Treatment.:Alternative medicine.
   Priapism is a painful erection that occurs for several hours and occurs in the absence of sexual stimulation. This condition develops when blood gets trapped in the penis and is unable to drain out. If the condition is not promptly treated, it can lead to severe scarring and permanent loss of erectile function. The disorder occurs in young men and children. Individuals with sickle-cell disease and those who abuse certain medications can often develop this disorder.
  
  Section::::Causes.
   Most complications are discovered within six months after surgery, although they occasionally are not found for many years. In general, when no problems are apparent after repair in childhood, new complications arising after puberty are uncommon. However, some problems that were not adequately repaired in childhood may become more pronounced when the penis grows at puberty, such as residual penile curvature or urine spraying due to rupture of the repair at the head of the penis.
   Erectile dysfunction or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis. There are various underlying causes, such as damage to the nervi erigentes which prevents or delays erection, or diabetes as well as cardiovascular disease, which simply decreases blood flow to the tissue in the penis, many of which are medically reversible.
   BULLET::::- Swyer Syndrome (Also known as Pure Gonadal Dysgenesis or XY gonadal dysgenesis) is a type of hypogonadism in a person whose karyotype is 46,XY. The person is externally female with streak gonads, and left untreated, will not experience puberty. Such gonads are typically surgically removed (as they have a significant risk of developing tumors) and a typical medical treatment would include hormone replacement therapy with female hormones.
   Most human penis growth occurs between infancy and the age of five, and between about one year after the onset of puberty and, at latest, approximately 17 years of age.
  
  A statistically significant correlation between penis size and the size of other body parts has not been found in research. Some environmental factors in addition to genetics, such as the presence of endocrine disruptors, can affect penis growth. An adult penis with an erect length of less than , but otherwise formed normally, is referred to in medicine as a micropenis.
  
  Section::::Studies.
   As a child grows the epiphyses become calcified and appear on the x-rays, as do the carpal and tarsal bones of the hands and feet, separated on the x-rays by a layer of invisible cartilage where most of the growth is occurring. As sex steroid levels rise during puberty, bone maturation accelerates. As growth nears conclusion and attainment of adult height, bones begin to approach the size and shape of adult bones. The remaining cartilaginous portions of the epiphyses become thinner. As these cartilaginous zones become obliterated, the epiphyses are said to be "closed" and no further lengthening of the bones will occur. A small amount of spinal growth concludes an adolescent's growth.
   A certain degree of curvature of the penis is considered normal, as many men are born with this benign condition, commonly referred to as congenital curvature.
   Regardless of the cause of micropenis, if it is recognized in infancy, a brief course of testosterone is often prescribed (usually no more than 3 months). This usually induces a small amount of growth, confirming the likelihood of further growth at puberty, but rarely achieves normal size. No additional testosterone is given during childhood, to avoid unwanted virilization and bone maturation. (There is also some evidence that premature administration of testosterone can lead to reduced penis size in the adult.)
   Androgens like testosterone are responsible for penis enlargement and elongation during puberty. Penis size is positively correlated with increasing testosterone levels during puberty. However, after puberty, administration of testosterone is not capable of affecting penis size, and androgen deficiency in adult men only results in a small decrease in size. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) are also involved in penis size, with deficiency (such as that observed in growth hormone deficiency or Laron syndrome) at critical developmental stages having the potential to result in micropenis.
  
  Section::::Variance.
  
  Section::::Variance.:Genetics.
   Section::::Description.:Growth cycle.
   Severe prenatal deficiency of GH, as occurs in congenital hypopituitarism, has little effect on fetal growth. However, prenatal and congenital deficiency can reduce the size of a male's penis, especially when gonadotropins are also deficient. Besides micropenis in males, additional consequences of severe deficiency in the first days of life can include hypoglycemia and exaggerated jaundice (both direct and indirect hyperbilirubinemia).
   Because ischemic priapism causes the blood to remain in the penis for unusually long periods of time, the blood becomes deprived of oxygen and can cause damage to the penile tissue itself. Should the penile tissue become damaged, it can result in erectile dysfunction or disfigurement of the penis. In extreme cases, if the penis develops severe vascular disease, the priapism can result in penile gangrene.
  
  Section::::Causes.
  
  Section::::Causes.:Low flow priapism.
   Most of the penis develops from the same tissue in the embryo as does the clitoris in females; the skin around the penis and the urethra come from the same embryonic tissue from which develops the labia minora in females. An erection is the stiffening and rising of the penis, which occurs during sexual arousal, though it can also happen in non-sexual situations. Spontaneous non-sexual erections frequently occur during adolescence and during sleep.
   Hypophysectomy performed at any age causes atrophy of the thyroid and adrenal glands as well as asthenia and cachexia. When the procedure is performed before sexual maturity, the reproductive tract remains undeveloped and non-functional. There is also a general lack of growth. If performed after sexual maturity, there will be a loss of reproductive function along with atrophy of gonads and accessory reproductive structures.
   The average stretched penile length at birth is about , and 90% of newborn boys will be between . Limited growth of the penis occurs between birth and 5 years of age, but very little occurs between 5 years and the onset of puberty. The average size at the beginning of puberty is with adult size reached about 5 years later. W.A. Schonfeld published a penis growth curve in 1943.
  
  Section::::Studies.:Size with ageing.
   BULLET::::- Diphallia (also known as penile duplication, diphallic terata, and diphallasparatus) - A condition where a male is born with two penises. It's extremely rare, with only 100 cases being recorded since 1609 and an occurrence rate of 1 in 5,500,000 in the United States. The penises may be side by side or one on top of the other, being of equal size or with one penis being distinctively larger than the other, and both penises may be suitable for urination and intercourse. Men with diphallia may be sterile.
   The scrotum may, but not always, become tightened during erection. Generally, the foreskin automatically and gradually retracts, exposing the glans, though some men may have to manually retract their foreskin.
  
  Section::::Physiology.:Autonomic control.
   Research by urologist Harry Fisch of the Male Reproductive Center at Columbia Presbyterian Hospital indicates that in humans this defect may be exclusively inherited from the father and becomes increasingly probable with paternal age: specifically males reproducing after 35.
  
  Section::::Causes.:Growth hormone deficiency.
   BULLET::::- In Alberto Moravia's novel, "Io e lui" ("Him and Me", 1971), the protagonist is in a constant unsuccessful quest to overcome the power of his large penis, so he sublimates into a serious film director.
   Growth hormone levels rise steadily throughout puberty. IGF1 levels rise and then decline as puberty ends. Growth finishes and adult height is attained as the estradiol levels complete closure of the epiphyses.
  
  Section::::Stages.
  
  BULLET::::- adrenarche (approximately age 11)
  
  BULLET::::- gonadarche (approximately age 8)
  
  BULLET::::- thelarche (approximately age 11 in females)
  
  BULLET::::- pubarche (approximately age 12)
  
  BULLET::::- menarche (approximately age 12.5 in females)
  
  BULLET::::- spermarche (approximately age 13.5 in males)
  
  Section::::See also.
  
  BULLET::::- Adolescent sexuality
  
  BULLET::::- Child sexuality
  
  BULLET::::- Delayed puberty
  
  BULLET::::- Eunuch
  
  BULLET::::- Hebephilia
  
  BULLET::::- Kallmann syndrome
  
  BULLET::::- Precocious puberty
  
  BULLET::::- Puberphonia
  
  BULLET::::- Secondary sex characteristic
  
  Section::::Further reading.
  