Puberty#Changes in males

{{wide image|Child development stages.svg|1200px|Approximate outline of development periods from childhood to early adulthood. Puberty is marked in green at right.}}

[[File:Hormons feedback - Sprzężenie zwrotne hormonow.svg|upright=1.35|thumb|

Hormone feedback cycles:

1 Follicle-stimulating hormone – FSH

2 Luteinizing hormone – LH

3 Progesterone

4 Estrogen

5 Hypothalamus

6 Pituitary gland

7 Ovary

8 Pregnancy – hCG (Human chorionic gonadotropin)

9 Testosterone

10 Testicle

11 Incentives

12 Prolactin – PRL]]

Two of the most significant differences between puberty in females and puberty in males are the age at which it begins, and the major sex steroids involved, the androgens and the estrogens.

Although there is a wide range of normal ages, females typically begin the process of puberty around age 10½; males at ages 11½—12. Puberty generally ends between 15—17 for females and 16–17 for males. Females attain reproductive maturity about four years after the first physical changes of puberty appear.{{cite web |title=Puberty and adolescence |publisher=University of Maryland |url=http://umm.edu/health/medical/ency/articles/puberty-and-adolescence |archive-url=https://web.archive.org/web/20130924134845/http://umm.edu/health/medical/ency/articles/puberty-and-adolescence |access-date=September 13, 2013|archive-date=2013-09-24 }} In contrast, males accelerate more slowly but continue to grow for about six years after the first visible pubertal changes.Garn, SM. Physical growth and development. In: Friedman SB, Fisher M, Schonberg SK., editors. Comprehensive Adolescent Health Care. St Louis: Quality Medical Publishing; 1992. Retrieved on 2009-02-20

For males, the androgen testosterone is the principal sex hormone; while testosterone is produced, all males' changes are characterized as virilization. A substantial product of testosterone metabolism in males is the estrogen estradiol. The conversion of testosterone to estradiol depends on the amount of body fat and estradiol levels in males are typically much lower than in females. The male "growth spurt" also begins later, accelerates more slowly, and lasts longer before the epiphyses fuse. Although males are on average {{convert|2|cm|in|1}} shorter than females before puberty begins, adult men are on average about {{convert|13|cm|in}} taller than women. Most of this sex difference in adult heights is attributable to a later onset of the growth spurt and a slower progression to completion, a direct result of the later rise and lower adult male levels of estradiol.{{cite journal | vauthors = Abbassi V | title = Growth and normal puberty. | journal = Pediatrics | volume = 102 | issue = 2 Pt 3 | pages = 507–513 | year = 1998 | doi = 10.1542/peds.102.S3.507 | pmid = 9685454 | s2cid = 24733669 }}

The hormonal maturation of females is considerably more complicated than in males. The main steroid hormones, testosterone, estradiol, and progesterone as well as prolactin play important physiological functions in puberty. The production of gonadal steroids in females starts with production of testosterone, which is typically quickly converted to estradiol inside the ovaries. However the rate of conversion from testosterone to estradiol (driven by FSH/LH balance) during early puberty is highly individual, resulting in very diverse development patterns of secondary sexual characteristics. Production of progesterone in the ovaries begins with the development of ovulatory cycles in females (during the lutheal phase of the cycle), before puberty low levels of progesterone are produced in the adrenal glands of both males and females. Estradiol levels rise earlier and reach higher levels in women than in men. While estradiol promotes growth of the breasts and uterus, it is also the principal hormone driving the pubertal growth spurt and epiphyseal maturation and closure.{{cite journal | vauthors = MacGillivray MH, Morishima A, Conte F, Grumbach M, Smith EP | title = Pediatric endocrinology update: an overview. The essential roles of estrogens in pubertal growth, epiphyseal fusion and bone turnover: lessons from mutations in the genes for aromatase and the estrogen receptor | journal = Hormone Research | volume = 49 | pages = 2–8 | year = 1998 | pmid = 9554463 | issue = Suppl 1 | doi = 10.1159/000053061 | s2cid = 72138474 }}

Puberty is preceded by adrenarche, marking an increase of adrenal androgen production between ages 6–10. Adrenarche is sometimes accompanied by the early appearance of axillary and pubic hair. The first androgenic hair resulting from adrenarche can be also transient and disappear before the onset of true puberty.

The onset of puberty is associated with high GnRH pulsing, which precedes the rise in sex hormones, LH and FSH.{{cite journal |vauthors=Plant TM |title=Leptin, growth hormone, and the onset of primate puberty |journal=The Journal of Clinical Endocrinology and Metabolism |volume=86 |issue=1 |pages=458–460 |year=2001 |pmid=11232044 |doi=10.1210/jc.86.1.459 |doi-access=free}} Exogenous GnRH pulses cause the onset of puberty.{{cite book |title=Essential Reproduction |vauthors=Johnson M |publisher=Blackwell Publishers |edition=6th Rev |date=29 Jun 2007}} Brain tumors which increase GnRH output may also lead to premature puberty.{{cite web |title=Precocious Puberty |publisher=MERCK |date=May 16, 2008 |url=http://www.merckmanuals.com/professional/pediatrics/endocrine_disorders_in_children/precocious_puberty.html?qt=&sc=&alt=}}

The cause of the GnRH rise is unknown. Leptin might be the cause of the GnRH rise. Leptin has receptors in the hypothalamus which synthesizes GnRH.{{cite journal | vauthors = Meister B, Håkansson ML | title = Leptin receptors in hypothalamus and circumventricular organs | journal = Clinical and Experimental Pharmacology & Physiology | volume = 28 | issue = 7 | pages = 610–617 | year = 2001 | pmid = 11458889 | doi = 10.1046/j.1440-1681.2001.03493.x | s2cid = 72146698 }} Individuals who are deficient in leptin fail to initiate puberty.{{cite journal | vauthors = Clayton PE, Trueman JA | title = Leptin and puberty | journal = Archives of Disease in Childhood | volume = 83 | issue = 1 | pages = 1–4 | year = 2000 | pmid = 10868988 | pmc = 1718397 | doi = 10.1136/adc.83.1.1 }} The levels of leptin increase with the onset of puberty, and then decline to adult levels when puberty is completed. The rise in GnRH might also be caused by genetics. A study discovered that a mutation in genes encoding both neurokinin B as well as the neurokinin B receptor can alter the timing of puberty.{{cite journal |vauthors=Topaloglu AK, Reimann F, Guclu M, Yalin AS, Kotan LD, Porter KM, Serin A, Mungan NO, Cook JR, Ozbek MN, Imamoglu S, Akalin NS, Yuksel B, O'Rahilly S, Semple RK |year=2009 |title=TAC3 and TACR3 mutations in familial hypogonadotropic hypogonadism reveal a key role for Neurokinin B in the central control of reproduction |journal=Nature Genetics |volume=41 |issue=3 |pages=354–358 |doi=10.1038/ng.306 |pmc=4312696 |pmid=19079066}} The researchers hypothesized that neurokinin B might play a role in regulating the secretion of kisspeptin, a compound responsible for triggering direct release of GnRH as well as indirect release of LH and FSH.

Several studies about puberty have examined the effects of an early or a late onset of puberty in males and females. In general, females who enter puberty late experience positive outcomes in adolescence and adulthood, while females who enter puberty early experience negative outcomes. Males who have earlier pubertal timing generally have more positive outcomes in adulthood but more negative outcomes in adolescence, while the reverse is true for later pubertal timing.{{Cite book|title = Invitation to the Life Span|url = https://archive.org/details/isbn_2901464172051|url-access = registration|last = Berger|first = Kathleen Stassen|publisher = Worth Publishers|year = 2014|location = New York|isbn = 978-1-4292-8352-6}}

Outcomes have generally indicated that early onset of puberty in females can be psychologically damaging. The main reason for this detrimental effect is the issue of body image. As they physically develop, gaining weight in several areas of the body, early-maturing females usually look larger than females who have not yet entered puberty. A result of the social pressure to be thin, the early-maturing females develop a negative view of their body image. In addition, people may tease the females about their visible breasts, forcing the early-maturing female to hide her breasts by dressing differently. Embarrassment about a more developed body may also result in the refusal to undress for gym. These experiences lead to lower self-esteem, more depression and poorer body image in these early-maturing females.

Furthermore, as physical and emotional differences set them apart from people in their same age group, early-maturing females develop relationships with older people. For instance, some early-maturing females have older malefriends, "attracted to the females' womanly physique and femaleish innocence." While having an older malefriend might improve popularity among peers, it also increases the risk of alcohol and drug use, increased sexual relations (often unprotected), eating disorders and bullying.

Generally, later onset of puberty in females produces positive outcomes. They exhibit positive behaviors in adolescence that continue to adulthood.

In the past, early onset of puberty in males has been associated with positive outcomes, such as leadership in high school and success in adulthood.{{Cite journal|title = A Longitudinal Investigation of Associations Between Boys' Pubertal Timing and Adult Behavioral Health and Well-Being|last = Taga|first = Keiko A.|date = 3 May 2006|journal = Journal of Youth and Adolescence|doi = 10.1007/s10964-006-9039-4|volume=35|issue = 3|pages=380–390|s2cid = 143325699}} However, recent studies have revealed that the risks and problems of early maturation in males might outweigh the benefits.

Early-maturing males develop "more aggressive, law-breaking, and alcohol abusing" behaviors, which result in anger towards parents and trouble in school and with the police. Early puberty also correlates with increased sexual activity and a higher instance of teenage pregnancy, both of which can lead to depression and other psychosocial issues.

On the other hand, late-maturing males develop lower self-esteem and confidence and generally have lower popularity among peers, due to their less-developed physiques. Also, they experience problems with anxiety and depression and are more likely to be afraid of sex than other males.

{{see also|Tanner scale}}

In males, puberty begins with the enlargement of the testicles and scrotum. The penis also increases in size, and a male develops pubic hair. A male's testicles also begin making sperm. The release of semen, which contains sperm and other fluids, is called ejaculation.{{cite web|url=https://www.hopkinsmedicine.org/health/wellness-and-prevention/puberty-adolescent-male |title=Puberty: Adolescent Male |website=Johns Hopkins Medicine |access-date=2020-02-27}} During puberty, a male's erect penis becomes capable of ejaculating semen and impregnating a female.{{cite web |title=Male Reproductive System Information |website=Cleveland Clinic |url=https://my.clevelandclinic.org/health/articles/9117-male-reproductive-system}}{{cite web|url=https://www.webmd.com/sex-relationships/guide/male-reproductive-system|title=The Male Reproductive System|website=WebMD}} A male's first ejaculation is an important milestone in his development.{{cite web |title=Male puberty milestones |publisher=Health24 |url=https://www.health24.com/Lifestyle/Teen/Your-body/Male-puberty-milestones-20120721 |access-date=2020-02-27}} On average, a male's first ejaculation occurs at age 13.{{sfn|Jorgensen|Keiding|Skakkebaek|1991}} Ejaculation sometimes occurs during sleep; this phenomenon is known as a nocturnal emission.

File:Male genitalia five Tanner stages.png

In males, testicular enlargement is the first physical manifestation of puberty (and is termed gonadarche).{{sfnp|Styne|2002|p=598}} Testes in prepubertal males change little in size from about 1 year of age to the onset of puberty, averaging about 2–3 cm in length and about 1.5–2 cm in width. The size of the testicles is among the parameters of the Tanner scale for male genitals, from stage I which represents a volume of less than 1.5 ml, to stage V which represents a testicular volume of greater than or equal to 20 ml. Testicular size reaches maximal adult size about 6 years after the onset of puberty. While 18–20 cm³ is an average adult size, there is wide variation in testicular size in the normal population.{{sfnp|Marshall|Tanner|1986|p=180}} After the male's testicles have enlarged and developed for about one year, the length and then the breadth of the shaft of the penis will increase and the glans penis and corpora cavernosa will also start to enlarge to adult proportions.{{Cite book |author=Jones, Kenneth W.|title=Smith's Recognizable Patterns of Human Malformation|publisher=Elsevier Saunders|location=St. Louis, Mo|year=2006|isbn=978-0-7216-0615-6}}

File:Adolescent Period Average boy 10 to 17 yo.jpg

Erections during sleep or when waking up are medically known as nocturnal penile tumescence and colloquially referred to as morning wood.{{Cite web |url=http://h2g2.com/approved_entry/A12219374 |title=h2g2 - The Morning Glory (or Nocturnal Penile Tumescence) |access-date=2013-11-09 |archive-date=2016-03-07 |archive-url=https://web.archive.org/web/20160307204830/http://h2g2.com/approved_entry/A12219374 |url-status=dead }} The penis can regularly get erect during sleep and men or males often wake up with an erection.{{Cite book|url=https://books.google.com/books?id=5f8mQx7ULs4C&pg=PA149|title=Sexuality Now: Embracing Diversity|first=Janell|last=Carroll|date=29 January 2009|publisher=Cengage Learning|isbn=978-0-495-60274-3 |via=Google Books}} Once a male reaches his teenage years, erections occur much more frequently due to puberty.{{Cite book|url=https://books.google.com/books?id=R0eixKqC0SgC&dq=erection+puberty&pg=PA119|title=What's Happening to My Body? Book for Boys: Revised Edition|first1=Lynda|last1=Madaras|first2=Area|last2=Madaras|date=8 June 2007|publisher=HarperCollins|isbn=978-1-55704-769-4 |via=Google Books}} Erections can occur spontaneously at any time of day, and if clothed may cause a bulge or "hump". This can be disguised or hidden by wearing close-fitting underwear, a long shirt and baggier clothes.{{Cite book|url=https://books.google.com/books?id=xLqwYAzogiwC&pg=PA62|title=Making Sense of Sex: A Forthright Guide to Puberty, Sex and Relationships for People with Asperger's Syndrome|first=Sarah|last=Attwood|date=15 May 2008|publisher=Jessica Kingsley Publishers|isbn=978-1-84642-797-8 |via=Google Books}} Erections are common for male prepubescent children and infants, and can even occur before birth.{{Cite web |url=http://www.livestrong.com/article/267344-erections-in-babies/ |title=Erections in Babies {{!}} LIVESTRONG.COM |access-date=2012-01-07 |archive-date=2012-10-04 |archive-url=https://web.archive.org/web/20121004004403/http://www.livestrong.com/article/267344-erections-in-babies/ |url-status=dead }} Spontaneous erections, also known as involuntary or unwanted erections, are normal. Such erections can be embarrassing if they happen in public, such as a classroom or living room.{{Cite book|url=https://books.google.com/books?id=R0eixKqC0SgC&dq=erection+spontaneous&pg=PA145|title=What's Happening to My Body? Book for Boys: Revised Edition|first1=Lynda|last1=Madaras|first2=Area|last2=Madaras|date=8 June 2007|publisher=HarperCollins|isbn=978-1-55704-769-4 |via=Google Books}}{{Cite book|url=https://books.google.com/books?id=qdybSBoC4_0C&dq=erection+spontaneous&pg=PA201|title=What's Happening to My Body? Book for Girls: Revised Edition|first1=Lynda|last1=Madaras|first2=Area|last2=Madaras|date=6 June 2007|publisher=HarperCollins|isbn=978-1-55704-764-9 |via=Google Books}}

During puberty, if not before, the tip and opening of a male's foreskin becomes wider, progressively allowing for retraction down the shaft of the penis and behind the glans, which ultimately should be possible without pain or difficulty. The membrane that bonds the inner surface of the foreskin with the glans disintegrates and releases the foreskin to separate from the glans. The foreskin then gradually becomes retractable.{{cite journal | vauthors = Øster J | title = Further Fate of the Foreskin: Incidence of Preputial Adhesions, Phimosis, and Smegma among Danish Schoolboys | journal = Arch Dis Child | volume = 43 | pages = 200–202 | date = April 1968 | issue = 228 | pmid = 5689532 | pmc = 2019851 | doi = 10.1136/adc.43.228.200}}

Research by Øster (1968) found that with the onset and continuation of puberty, the proportion of males able to pull back their foreskins increased. At ages 12–13, Øster found that only 60% of males were able to retract their foreskins; this increased to 85% by ages 14–15, and 95% by 16–17. He also found that 1% of those unable to fully retract experienced phimosis at ages 14–17, the remainder were partially able to. The findings were supported by further research by Kayaba et al (1996) on a sample of over 600 males,{{cite journal |vauthors=Kayaba H, Tamura H, Kitajima S, Fujiwara Y, Kato T, Kato T | title = Analysis of Shape and Retractability of the Prepuce in 603 Japanese Boys | journal = J Urol | volume = 156 | issue = 5 | pages = 1813–1815 | date = November 1996 | pmid = 8863623 | doi = 10.1016/S0022-5347(01)65544-7 | publisher = American Urological Association, Inc. }} and Ishikawa and Kawakita (2004) found that by age 15, 77% of their sample of males could retract their foreskins.{{cite journal| vauthors =Ishikawa E, Kawakita M |title=Preputial development in Japanese boys |journal= Hinyokika Kiyo |year= 2004 |volume=50 |issue=5 |pages=305–8|pmid= 15237481}} Beaugé (1997) reports that males may assist the development of retractile foreskin by manual stretching.{{cite journal | vauthors=Beaugé M | title=The causes of adolescent phimosis | journal=Br J Sex Med | date=1997 | volume= | issue=Sept/Oct | pages=26 | doi= | pmid= | pmc= }}

Once a male is able to retract his foreskin, penile hygiene should become an important feature of his routine body care. Although the American Academy of Pediatrics states there is "little evidence to affirm the association between circumcision status and optimal penile hygiene",{{cite journal | title = Circumcision Policy Statement | journal = Pediatrics | volume = 103 | issue = 3 | pages = 686–93 | year = 1999 | pmid = 10049981 | doi = 10.1542/peds.103.3.686 | doi-access = free }} various studies suggest that males be educated about the role of hygiene, including retracting the foreskin while urinating and rinsing under it and around the glans at each bathing opportunity. Regular washing under the foreskin was found by Krueger and Osborn (1986) to reduce the risk of numerous penile disorders,{{cite journal |vauthors=Krueger H, Osborn L | title = Effects of hygiene among the uncircumcised | journal = J Fam Pract | volume = 22 | issue = 4 | pages = 353–5 | year = 1986 | pmid = 3958682 }} however Birley et al. (1993) reports excessive washing with soap should be avoided because it dries the oils out of the tissues and can cause non-specific dermatitis.{{cite journal | vauthors=Birley HD, Luzzi GA, Bell R | title=Clinical features and management of recurrent balanitis: association with atopy and genital washing | journal=Genitourin Med | date=1993 | volume=69 | issue=5 | pages=400–403 | doi=10.1136/sti.69.5.400| pmid=8244363 | pmc=1195128 }}File:Boy through puberty 11.3yo (prepuberal) 12.5yo, 14.9yo and 16.3yo (post puberal).jpg

Image:Stubbly face.jpg of a male]]

In the months and years following the appearance of pubic hair, other areas of skin that respond to androgens may develop androgenic hair. The usual sequence is: underarm (axillary) hair, perianal hair, upper lip hair, sideburn (preauricular) hair, periareolar hair, and the beard area.{{Cite news|title=Puberty -- Changes for Males|publisher=pamf.org|access-date=2009-02-20 |url=http://www.pamf.org/teen/health/puberty/physicalchanges.html}} As with most human biological processes, this specific order may vary among some individuals. Arm, leg, chest, abdominal, and back hair become heavier more gradually. There is a large range in amount of body hair among adult men, and significant differences in timing and quantity of hair growth among different racial groups. Facial hair is often present in late adolescence, but may not appear until significantly later.{{cite web|title=Getting The Facts: Puberty|publisher=ppwr|access-date=2009-02-20|url=http://www.ppwr.on.ca/03_07.html|archive-url=https://web.archive.org/web/20080104233250/http://www.ppwr.on.ca/03_07.html|archive-date=2008-01-04}}{{Cite news|title=The No-Hair Scare|publisher=PBS|access-date=2009-02-20|url=http://pbskids.org/itsmylife/body/puberty/article7.html|url-status=dead|archive-url=https://web.archive.org/web/20090205115944/http://pbskids.org/itsmylife/body/puberty/article7.html|archive-date=2009-02-05}} Facial hair will continue to get coarser, darker and thicker for another 2–4 years after puberty. Some men do not develop full facial hair for up to 10 years after the completion of puberty.

{{main|Voice change|Adam's apple}}

{{Redirect|Squeaky-voiced Teen|the The Simpsons character|Squeaky-Voiced Teen}}

Under the influence of androgens, the larynx (or voice box) grows in both sexes. This growth is far more prominent in males, causing the male voice to drop and deepen, sometimes abruptly but rarely "overnight", about one octave, because the longer and thicker vocal folds have a lower fundamental frequency. Before puberty, the larynx of males and females is about equally small.{{cite encyclopedia|title=The structure of the larynx|encyclopedia=Encyclopædia Britannica|access-date=2009-02-20|url=http://global.britannica.com/EBchecked/topic/559032/speech/68966/The-structure-of-the-larynx}}

File:Female breasts five Tanner stages.jpg of puberty in females]]

{{Main|Breast development}}

The first physical sign of puberty in females is usually a firm, tender lump under the center of the areola of one or both breasts, occurring on average at about 10½ years of age.{{sfnp|Marshall|Tanner|1986|p=187}} This is referred to as thelarche. By the widely used Tanner staging of puberty, this is stage 2 of breast development (stage 1 is a flat, prepubertal breast). Within 6–12 months, the swelling has clearly begun in both sides, softened, and can be felt and seen extending beyond the edges of the areolae. This is stage 3 of breast development. By another 12 months (stage 4), the breasts are approaching mature size and shape, with areolae and nipples forming a secondary mound. In most young women, this mound disappears into the contour of the mature breast (stage 5), although there is so much variation in sizes and shapes of adult breasts that stages 4 and 5 are not always separately identifiable.{{sfnp|Marshall|Tanner|1986|p=188}}

Pubic hair is often the second noticeable change in puberty, usually within a few months of thelarche.{{cite journal |vauthors=Tanner JM, Davies PS | title = Clinical longitudinal standards for height and height velocity for North American children. | journal = The Journal of Pediatrics | volume = 107 | issue = 3 | pages = 317–329 | year = 1985 | pmid = 3875704 | doi = 10.1016/S0022-3476(85)80501-1 }} It is referred to as pubarche. The pubic hairs are usually visible first along the labia. The first few hairs are described as Tanner stage 2.{{sfnp|Marshall|Tanner|1986|p=188}} Stage 3 is usually reached within another 6–12 months, when the hairs are too numerous to count and appear on the pubic mound as well. By stage 4, the pubic hairs densely fill the "pubic triangle". Stage 5 refers to spread of pubic hair to the thighs and sometimes as abdominal hair upward towards the navel. In about 15% of females, the earliest pubic hair appears before breast development begins.

Perineal skin keratinizes due to effect of estrogen increasing its resistance to infection. The mucosal surface of the vagina also changes in response to increasing levels of estrogen, becoming thicker and duller pink in color (in contrast to the brighter red of the prepubertal vaginal mucosa).{{sfnp|Gordon|Laufer|2005|p=151}} Mucosa changes into a multilayered structure with superficial layer of squamous cells. Estrogen increase glycogen content in vaginal epithelium, which in future plays important part in maintaining vaginal pH. Whitish secretions (physiologic leukorrhea) are a normal effect of estrogen as well.{{sfnp|Marshall|Tanner|1986|p=187}} In the two years following thelarche, the uterus, ovaries, and the follicles in the ovaries increase in size.{{sfnp|Marshall|Tanner|1986|pp=186–187}} The ovaries usually contain small follicular cysts visible by ultrasound.{{sfnp|Rosenfield|2002|p=462}}{{cite journal |vauthors=Siegel MJ, Surratt JT |title=Pediatric gynecologic imaging |journal=Obstetrics and Gynecology Clinics of North America |volume=19 |issue=1 |pages=103–127 |year=1992 |doi=10.1016/S0889-8545(21)00504-0 |pmid=1584537}}

The first menstrual bleeding is referred to as menarche, and typically occurs about two years after thelarche. The average age of menarche is 12½ in the United States.{{cite journal |vauthors=Anderson SE, Dallal GE, Must A |title=Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart |journal=Pediatrics |volume=111 |issue=4 Pt 1 |pages=844–850 |date=April 2003 |pmid=12671122 |doi=10.1542/peds.111.4.844 }} Most American females experience their first period at 11, 12 or 13, but some experience it earlier than their 11th birthday and others after their 14th birthday. In fact, anytime between 8 and 16 is normal. In Canada, the average age of menarche is 12.72,{{cite journal |vauthors=Al-Sahab B, Ardern CI, Hamadeh MJ, Tamim H |title=Age at menarche in Canada: results from the National Longitudinal Survey of Children & Youth |journal=BMC Public Health |volume=10 |issue=1 |page=736 |year=2010 |pmid=21110899 |pmc=3001737 |doi=10.1186/1471-2458-10-736 |doi-access=free }} and in the United Kingdom it is 12.9.{{cite book |last=Hamilton-Fairley |first=Diana |year=2004 |title=Obstetrics and Gynaecology |edition=2nd |publisher=Blackwell Publishing |url=http://vstudentworld.yolasite.com/resources/final_yr/gynae_obs/Hamilton%20Fairley%20Obstetrics%20and%20Gynaecology%20Lecture%20Notes%202%20Ed.pdf |access-date=2013-11-09 |archive-date=2018-10-09 |archive-url=https://web.archive.org/web/20181009065351/http://vstudentworld.yolasite.com/resources/final_yr/gynae_obs/Hamilton%20Fairley%20Obstetrics%20and%20Gynaecology%20Lecture%20Notes%202%20Ed.pdf |url-status=dead}} The time between menstrual periods (menses) is not always regular in the first two years after menarche.{{cite journal |vauthors=Apter D |title=Serum steroids and pituitary hormones in female puberty: a partly longitudinal study |journal=Clinical Endocrinology |volume=12 |issue=2 |pages=107–120 |year=1980 |pmid=6249519 |doi=10.1111/j.1365-2265.1980.tb02125.x |s2cid=19913395}} Ovulation is necessary for fertility, but may or may not accompany the earliest menses.{{sfnp|Marshall|Tanner|1986|pp=196-197}} In postmenarchal females, about 80% of the cycles were anovulatory in the first year after menarche, 50% in the third year and 10% in the sixth year. Initiation of ovulation after menarche is not inevitable. A high proportion of females with continued irregularity in the menstrual cycle several years from menarche will continue to have prolonged irregularity and anovulation, and are at higher risk for reduced fertility.{{cite journal |vauthors=Southam AL, Richart RM |title=The prognosis for adolescents with menstrual abnormalities |journal=American Journal of Obstetrics and Gynecology |volume=94 |issue=5 |pages=637–645 |year=1966 |pmid=5906589 |doi=10.1016/0002-9378(66)90398-X}}

File:Adolescent Period Average girl 4 to 16 yo.jpg

During this period, also in response to rising levels of estrogen, the lower half of the pelvis and thus hips widen (providing a larger birth canal).{{sfnp|Marshall|Tanner|1986|p=188}}{{cite web |url=http://www.columbia.edu/itc/hs/pubhealth/modules/reproductiveHealth/anatomy.html |title=Hips widen during female puberty |publisher=Columbia |access-date=2013-11-09}} Fat tissue increases to a greater percentage of the body composition than in males, especially in the typical female distribution of breasts, hips, buttocks, thighs, upper arms, and pubis. Progressive differences in fat distribution as well as sex differences in local skeletal growth contribute to the typical female body shape by the end of puberty. On average, at 10 years, females have 6% more body fat than males.{{sfnp|Gungor|Arslanian|2002|pp=699-700}}

Rising levels of androgens can change the fatty acid composition of perspiration, resulting in a more "adult" body odor. This often precedes thelarche and pubarche by one or more years. Another androgen effect is increased secretion of oil (sebum) from the skin. This change increases the susceptibility to acne, a skin condition that is characteristic of puberty. Acne varies greatly in its severity.{{sfnp|Rosenfield|2002|p={{Page needed|date=September 2010}}}}

Testosterone will cause an enlargement of the clitoris and possibly has important effects on the growth and maturation of the vestibular bulbs, corpora cavernosa of the clitoris and urethral sponge.{{cite journal |vauthors=Kalloo NB, Gearhart JP, Barrack ER | title = Sexually dimorphic expression of estrogen receptors, but not of androgen receptors in human fetal external genitalia | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 77 | issue = 3 | pages = 692–698 | year = 1993 | pmid = 8370691 | doi=10.1210/jcem.77.3.8370691}}

Changes of the vulva initiated by estradiol as well as its direct effects also appear to influence the functioning of the lower urinary tract.{{cite journal |vauthors=Andersson KE, Wein AJ | title = Pharmacology of the Lower Urinary Tract: Basis for Current and Future Treatments of Urinary Incontinence | journal = Pharmacological Reviews | volume = 56 | issue = 4 | pages = 581–631 | year = 2004 | pmid = 15602011 | doi = 10.1124/pr.56.4.4 | s2cid = 15746586 }}{{cite journal |vauthors=Robinson D, Cardozo L | title = Estrogens and the lower urinary tract | journal = Neurourology and Urodynamics | volume = 30 | issue = 5 | pages = 754–757 | year = 2011 | pmid = 21661025 | doi = 10.1002/nau.21106 | s2cid = 36951754 }}

Hair growth develops under the arms, starting out sparse before thickening and darkening over time.{{Cite web|url=https://kidshealth.org/en/teens/puberty.html|title=Everything You Wanted to Know About Puberty (for Teens) - KidsHealth|website=kidshealth.org|access-date=2019-08-23}}

File:Variations of the height of three boys from 12yo to the end of their growth spurt.jpg

In a general sense, the conclusion of puberty is reproductive maturity. Criteria for defining the conclusion may differ for different purposes: attainment of the ability to reproduce, achievement of maximal adult height, maximal gonadal size, or adult sex hormone levels. Maximal adult height is achieved at an average age of 15 years for an average female and 18 years for an average male. Potential fertility (sometimes termed nubility) usually precedes completion of growth by 1–2 years in females and 3–4 years in males. Stage 5 typically represents maximal gonadal growth and adult hormone levels.{{Citation needed|date=November 2024}}

The definition of the onset of puberty may depend on perspective (e.g., hormonal versus physical) and purpose (establishing population normal standards, clinical care of early or late pubescent individuals, etc.). A common definition for the onset of puberty is physical changes to a person's body. These physical changes are the first visible signs of neural, hormonal, and gonadal function changes.

The age at which puberty begins varies between individuals; usually, puberty begins between 10 and 13 years of age. The age at which puberty begins is affected by both genetic factors and by environmental factors such as nutritional state and social circumstances.{{cite journal |vauthors=Kaplowitz PB, Slora EJ, Wasserman RC, Pedlow SE, Herman-Giddens ME | title = Earlier onset of puberty in girls: relation to increased body mass index and ethnicity. | journal = Pediatrics | volume = 108 | issue = 2 | pages = 347–53 | year = 2001 | pmid = 11483799 | doi = 10.1542/peds.108.2.347 }} An example of social circumstances is the Vandenbergh effect; a juvenile female mouse who has significant interaction with adult male mice will enter puberty earlier than juvenile females who are not socially overexposed to adult males.{{cite book |last=Nelson |first=RJ |author-link=Randy J. Nelson | date=2005 |title=An Introduction to Behavioral Endocrinology |edition=3rd |publisher=Sinauer Associates |publication-place=Sunderland, Mass |page=357 |isbn=0-87893-617-3 }}

The average age at which puberty begins may be affected by ethnicity as well. For example, the average age of menarche in various populations surveyed has ranged from 12 to 18 years. The earliest average onset of puberty is for African-American females and the latest average onset for high altitude subsistence populations in Asia. However, much of the higher age averages reflect nutritional limitations more than genetic differences and can change within a few generations with a substantial change in diet. The median age of menarche for a population may be an index of the proportion of undernourished females in the population, and the width of the spread may reflect unevenness of wealth and food distribution in a population.

Researchers have identified an earlier age of the onset of puberty. However, they have based their conclusions on a comparison of data from 1999 with data from 1969. In the earlier example, the sample population was based on a small sample of white females (200, from Britain). The later study identified as puberty as occurring in 48% of African-American females by age nine, and 12% of white females by that age.{{Cite news |url=http://center4research.org/child-teen-health/early-puberty-and-problems-in-sexual-development/girls-to-women/|access-date=2010-07-13|archive-url=https://web.archive.org/web/20131109061104/http://center4research.org/child-teen-health/early-puberty-and-problems-in-sexual-development/girls-to-women/|url-status=dead|archive-date=2013-11-09|date=May 2009 |last=Zuckerman|first=Diana|title=Early Puberty in Girls|publisher=National Research Center for Women and Families}} Based on a publication from The Ribbon, a newsletter of the Cornell University Program on Breast Cancer and Environmental Risk Factors in New York States ((BCERF), Vol 6, No. 1, Winter 2001.)

One possible cause of a delay in the onset of puberty past the age 14 in females and 15 in males is Kallmann syndrome, a form of hypogonadotropic hypogonadism (HH). Kallmann syndrome is also associated with a lack of sense of smell (anosmia). Kallmann syndrome and other forms of HH affect both men and women. It is caused by a failure in HPG axis at puberty which results in low or zero gonadotropin (LH and FSH) levels with the subsequent result of a failure to commence or complete puberty, secondary hypogonadism and infertility.{{cite journal |vauthors=Mitchell AL, Dwyer A, Pitteloud N, Quinton R | title = Genetic basis and variable phenotypic expression of Kallmann syndrome: towards a unifying theory. | journal = Trends Endocrinol. Metab. | volume = 22 | issue = 7 | pages = 249–58 | year = 2011 | pmid = 21511493 | doi = 10.1016/j.tem.2011.03.002 | s2cid = 23578201 }}{{cite book |series=Oxford Endocrinology Library |title=Testosterone Deficiency in Men |publisher=Oxford University Press |year=2008 |isbn=978-0-19-954513-1 |editor=Hugh Jones |chapter=Chapter 9. Puberty & Fertility}}{{page needed|date=September 2022}}

{{center|Comparison of two individual with vast difference in the age of onset of puberty:}}

File:Early and late maturing boys 11.5 to 16.6.jpg

File:Early and late maturing girls 8.0 to 14.5 yo.png

The average age at which the onset of puberty occurs has dropped significantly since the 1840s.{{Cite news|first=Harry|last=Finley|title=Average age at menarche in various cultures|publisher=Museum of Menstruation and Women's Health|url=http://www.mum.org/menarage.htm|access-date=2007-08-02}}{{cite journal |vauthors=Whincup PH, Gilg JA, Odoki K, Taylor SJ, Cook DG |title=Age of menarche in contemporary British teenagers: survey of girls born between 1982 and 1986 |journal=BMJ |volume=322 |issue=7294 |pages=1095–1096 |year=2001 |pmid=11337438 |pmc=31261 |doi=10.1136/bmj.322.7294.1095}}{{cite news|title=Girls maturing slightly earlier|date=2001-05-03|work=BBC News |url=http://news.bbc.co.uk/2/hi/health/1310280.stm|access-date=2007-08-02}}

A 2006 study in Denmark found that puberty, as evidenced by breast development, started at an average age of 9 years and 10 months, a year earlier than when a similar study was done in 1991. Scientists believe the phenomenon could be linked to obesity or exposure to chemicals in the food chain, and is putting females at greater long-term risk of breast cancer.{{cite news |last=Rogers |first=Lois |date=2010-06-13 |title=Girls now begin puberty aged 9 |work=The Times |location=London |url=https://www.thetimes.com/uk/science/article/girls-now-begin-puberty-aged-9-9v8fc6x3fmk}}

Various studies have found direct genetic effects to account for at least 46% of the variation of timing of puberty in well-nourished populations.{{Cite journal |last1=Ge |first1=Xiaojia |last2=Natsuaki |first2=Misaki N. |last3=Neiderhiser |first3=Jenae M. |last4=Reiss |first4=David |title=Genetic and Environmental Influences on Pubertal Timing: Results From Two National Sibling Studies |journal=Journal of Research on Adolescence |volume=17 |issue=4 |pages=767–788 |year=2007 |doi=10.1111/j.1532-7795.2007.00546.x}}{{cite journal |vauthors=Mustanski BS, Viken RJ, Kaprio J, Pulkkinen L, Rose RJ |title=Genetic and environmental influences on pubertal development: longitudinal data from Finnish twins at ages 11 and 14 |journal=Developmental Psychology |volume=40 |issue=6 |pages=1188–1198 |year=2004 |pmid=15535766 |doi=10.1037/0012-1649.40.6.1188}}{{cite journal |vauthors=Treloar SA, Martin NG |title=Age at menarche as a fitness trait: nonadditive genetic variance detected in a large twin sample |journal=American Journal of Human Genetics |volume=47 |issue=1 |pages=137–148 |year=1990 |pmid=2349942 |pmc=1683767}}{{cite journal |vauthors=Kaprio J, Rimpelä A, Winter T, Viken RJ, Rimpelä M, Rose RJ |title=Common genetic influences on BMI and age at menarche |journal=Human Biology; an International Record of Research |volume=67 |issue=5 |pages=739–753 |year=1995 |pmid=8543288}} The genetic association of timing is strongest between mothers and daughters. The specific genes affecting timing are not yet known. Among the candidates is an androgen receptor gene.{{cite journal |vauthors=Comings DE, Muhleman D, Johnson JP, MacMurray JP |title=Parent-daughter transmission of the androgen receptor gene as an explanation of the effect of father absence on age of menarche |journal=Child Development |volume=73 |issue=4 |pages=1046–1051 |year=2002 |pmid=12146732 |doi=10.1111/1467-8624.00456}}

Researchers have hypothesized that early puberty onset may be caused by certain hair care products containing estrogen or placenta, and by certain chemicals, namely phthalates, which are used in many cosmetics, toys, and plastic food containers.

There is theoretical concern, and animal evidence, that environmental hormones and chemicals may affect aspects of prenatal or postnatal sexual development in humans.{{cite book|last1=Colborn|first1=Theo|last2=Dumanoski|first2=Dianne|last3=Myers|first3=John Peterson|title=Our Stolen Future|year=1996|publisher=Little, Brown|isbn=0316875465}}{{Page needed|date=September 2010}}

Bisphenol A (BPA) is a chemical used to make plastics, and is frequently used to make baby bottles, water bottles, sports equipment, medical devices, and as a coating in food and beverage cans. Scientists are concerned about BPA's behavioral effects on fetuses, infants, and children at current exposure levels because it can affect the prostate gland, mammary gland, and lead to early puberty in females. BPA mimics and interferes with the action of estrogen—an important reproduction and development regulator. It leaches out of plastic into liquids and foods, and the Centers for Disease Control and Prevention (CDC) found measurable amounts of BPA in the bodies of more than 90 percent of the U.S. population studied. The highest estimated daily intakes of BPA occur in infants and children. Many plastic baby bottles contain BPA, and BPA is more likely to leach out of plastic when its temperature is increased, as when one warms a baby bottle or warms up food in the microwave.{{cite web |url=http://center4research.org/child-teen-health/early-puberty-and-problems-in-sexual-development/are-bisphenol-a-bpa-plastic-products-safe-for-infants-and-children/ |title=Are Bisphenol A (BPA) Plastic Products Safe for Infants and Children? |access-date=2013-11-09 |archive-date=2020-08-06 |archive-url=https://web.archive.org/web/20200806125154/http://center4research.org/child-teen-health/early-puberty-and-problems-in-sexual-development/are-bisphenol-a-bpa-plastic-products-safe-for-infants-and-children/ |url-status=dead }}

Nutritional factors are the strongest and most obvious environmental factors affecting timing of puberty.

Scientific researchers have linked early obesity with an earlier onset of puberty in females. They have cited obesity as a cause of breast development before nine years and menarche before twelve years.{{cite magazine|first=Phil|last=McKenna|title=Childhood obesity brings early puberty for girls|magazine=New Scientist|date=2007-03-05|access-date=2010-05-22|url=https://www.newscientist.com/article/dn11307-childhood-obesity-brings-early-puberty-for-girls.html |archive-url = https://web.archive.org/web/20080419072722/http://www.newscientist.com/article/dn11307-childhood-obesity-brings-early-puberty-for-girls.html |archive-date = 2008-04-19}} Early puberty in females can be a harbinger of later health problems.Molly, M. Ginty, [http://womensenews.org/story/campaign-trail/060522/peru-campaign-quiet-reproductive-issues "US Girls' Early Puberty Attracts Research Flurry"], Women's eNews

Mental illnesses occur in puberty. The brain undergoes significant development by hormones which can contribute to mood disorders such as major depressive disorder, bipolar disorder, dysthymia and schizophrenia. Females aged between 15 and 19 make up 40% of anorexia nervosa cases.{{cite journal |vauthors=Bulik CM, Reba L, Siega-Riz AM, Reichborn-Kjennerud T | title = Anorexia nervosa: definition, epidemiology, and cycle of risk. | journal = The International Journal of Eating Disorders | volume = 37 | pages = S2–9; discussion S20–1 | year = 2005 | issue = Suppl 1 | pmid = 15852310 | doi = 10.1002/eat.20107 | doi-access = free }}

{{More citations needed section|date=November 2024}}

The endocrine reproductive system consists of the hypothalamus, the pituitary, the gonads, and the adrenal glands, with input and regulation from many other body systems. True puberty is often termed "central puberty" because it begins as a process of the central nervous system. A simple description of hormonal puberty is as follows:

1. The brain's hypothalamus begins to release pulses of GnRH.
2. Cells in the anterior pituitary respond by secreting LH and FSH into the circulation.
3. The ovaries or testes respond to the rising amounts of LH and FSH by growing and beginning to produce estradiol and testosterone.
4. Rising levels of estradiol and testosterone produce the body changes of female and male puberty.

The onset of this neurohormonal process may precede the first visible body changes by 1–2 years.

The arcuate nucleus of the hypothalamus is the driver of the reproductive system. It has neurons which generate and release pulses of GnRH into the portal venous system of the pituitary gland. The arcuate nucleus is affected and controlled by neuronal input from other areas of the brain and hormonal input from the gonads, adipose tissue and a variety of other systems.

The pituitary gland responds to the pulsed GnRH signals by releasing LH and FSH into the blood of the general circulation, also in a pulsatile pattern.

The gonads (testes and ovaries) respond to rising levels of LH and FSH by producing the steroid sex hormones, testosterone and estrogen.

The adrenal glands are a second source for steroid hormones. Adrenal maturation, termed adrenarche, typically precedes gonadarche in mid-childhood.

• Neurokinin B (a tachykinin peptide) and kisspeptin (a neuropeptide), both present in KNDy neurons of the hypothalamus, are critical parts of the control system that switches on the release of GnRH at the start of puberty.{{cite journal |vauthors=Topaloglu AK, Reimann F, Guclu M, Yalin AS, Kotan LD, Porter KM, Serin A, Mungan NO, Cook JR, Ozbek MN, Imamoglu S, Akalin NS, Yuksel B, O'Rahilly S, Semple RK |title= TAC3 and TACR3 mutations in familial hypogonadotropic hypogonadism reveal a key role for Neurokinin B in the central control of reproduction |journal=Nature Genetics |volume=41 |issue=3 |pages=354–358 |year=2008 |pmid=19079066 |pmc=4312696 |doi=10.1038/ng.306}}
  Lay summary: {{cite web |title=Key to regulation of puberty discovered |date=2008-12-11 |website=(e) Science News |url=http://esciencenews.com/articles/2008/12/11/key.regulation.puberty.discovered}}
• GnRH (gonadotropin-releasing hormone) is a peptide hormone released from the hypothalamus which stimulates gonadotrope cells of the anterior pituitary.
• LH (luteinizing hormone) is a larger protein hormone secreted into the general circulation by gonadotrope cells of the anterior pituitary gland. The main target cells of LH are the Leydig cells of testes and the theca cells of the ovaries. LH secretion changes more dramatically with the initiation of puberty than FSH, as LH levels increase about 25-fold with the onset of puberty, compared with the 2.5-fold increase of FSH.
• FSH (follicle stimulating hormone) is another protein hormone secreted into the general circulation by the gonadotrope cells of the anterior pituitary. The main target cells of FSH are the ovarian follicles and the Sertoli cells and spermatogenic tissue of the testes.
• Testosterone is a steroid hormone produced primarily by the Leydig cells of the testes, and in lesser amounts by the theca cells of the ovaries and the adrenal cortex. Testosterone is the primary mammalian androgen and the "original" anabolic steroid. It acts on androgen receptors in responsive tissue throughout the body.
• Estradiol is a steroid hormone produced by aromatization of testosterone. Estradiol is the principal human estrogen and acts on estrogen receptors throughout the body. The largest amounts of estradiol are produced by the granulosa cells of the ovaries, but lesser amounts are derived from testicular and adrenal testosterone.
• Adrenal androgens are steroids produced by the zona reticulosa of the adrenal cortex in both sexes. The major adrenal androgens are dehydroepiandrosterone, androstenedione (which are precursors of testosterone), and dehydroepiandrosterone sulfate which is present in large amounts in the blood. Adrenal androgens contribute to the androgenic events of early puberty in females.
• IGF1 (insulin-like growth factor 1) rises substantially during puberty in response to rising levels of growth hormone and may be the principal mediator of the pubertal growth spurt.
• Leptin is a protein hormone produced by adipose tissue. Its primary target organ is the hypothalamus. The leptin level seems to provide the brain a rough indicator of adipose mass for purposes of regulation of appetite and energy metabolism. It also plays a permissive role in female puberty, which usually will not proceed until an adequate body mass has been achieved.

The endocrine reproductive system becomes functional by the end of the first trimester of fetal life. The testes and ovaries become briefly inactive around the time of birth but resume hormonal activity until several months after birth, when incompletely understood mechanisms in the brain begin to suppress the activity of the arcuate nucleus. This has been referred to as maturation of the prepubertal "gonadostat", which becomes sensitive to negative feedback by sex steroids. The period of hormonal activity until several months after birth, followed by suppression of activity, may correspond to the period of infant sexuality, followed by a latency stage, which Sigmund Freud described.{{cite journal |vauthors=Lehrer S |title=Modern correlates of Freudian psychology. Infant sexuality and the unconscious. |journal=The American Journal of Medicine |volume=77 |issue=6 |pages=977–980 |year=1984 |pmid=6507468 |doi=10.1016/0002-9343(84)90172-4 |url=http://sites.google.com/site/infantsexuality/ |access-date=2009-05-03 |archive-date=2011-09-21 |archive-url=https://web.archive.org/web/20110921112324/http://sites.google.com/site/infantsexuality/ |url-status=dead }}

Neurons of the arcuate nucleus secrete gonadotropin releasing hormone (GnRH) into the blood of the pituitary portal system. An American physiologist, Ernst Knobil, found that the GnRH signals from the hypothalamus induce pulsed secretion of LH (and to a lesser degree, FSH) at roughly 1–2 hour intervals. The LH pulses are the consequence of pulsatile GnRH secretion by the arcuate nucleus that, in turn, is the result of an oscillator or signal generator in the central nervous system ("GnRH pulse generator").{{cite journal |vauthors=Neill JD |title=In Memoriam: Ernst Knobil (1926-2000) |journal=Endocrine Reviews |volume=22 |issue=6 |pages=721–723 |year=2001 |doi=10.1210/edrv.22.6.8566 |pmid=11739328|s2cid=1634732 |doi-access=free }} In the years preceding physical puberty, Robert M. Boyar discovered that the gonadotropin pulses occur only during sleep, but as puberty progresses they can be detected during the day.{{cite journal |vauthors=Boyar R, Finkelstein J, Roffwarg H, Kapen S, Weitzman E, Hellman L |title=Synchronization of augmented luteinizing hormone secretion with sleep during puberty |journal=The New England Journal of Medicine |volume=287 |issue=12 |pages=582–586 |year=1972 |pmid=4341276 |doi=10.1056/NEJM197209212871203}} By the end of puberty, there is little day-night difference in the amplitude and frequency of gonadotropin pulses.

Some investigators have attributed the onset of puberty to a resonance of oscillators in the brain.{{cite journal |vauthors=Sizonenko PC, Aubert ML | title = Neuroendocrine changes characteristic of sexual maturation. | journal = Journal of Neural Transmission. Supplementum | volume = 21 | pages = 159–181 | year = 1986 | pmid = 3462329 }}{{cite journal | vauthors = Rivest RW | title = Sexual maturation in female rats: hereditary, developmental and environmental aspects. | journal = Experientia | volume = 47 | issue = 10 | pages = 1027–1038 | year = 1991 | pmid = 1936201 | doi=10.1007/bf01923338| s2cid = 28120306 }}{{cite journal |vauthors=Yellon SM, Newman SW | title = A developmental study of the gonadotropin-releasing hormone neuronal system during sexual maturation in the male Djungarian hamster. | journal = Biology of Reproduction | volume = 45 | issue = 3 | pages = 440–446 | year = 1991 | pmid = 1782292 | doi = 10.1095/biolreprod45.3.440 | doi-access = free }} By this mechanism, the gonadotropin pulses that occur primarily at night just before puberty represent beats.{{cite journal | vauthors = Lehrer S | title = Puberty and resonance: a hypothesis. | journal = The Mount Sinai Journal of Medicine, New York | volume = 50 | issue = 1 | pages = 39–43 | year = 1983 | pmid = 6601758 | url = http://stevenlehrer.com/images/pubres.pdf }}{{cite journal | vauthors = Lehrer S | title = Rats on 22.5-hr light:dark cycles have vaginal opening earlier than rats on 26-hr light:dark cycles. | journal = Journal of Pineal Research | volume = 3 | issue = 4 | pages = 375–378 | year = 1986 | pmid = 3783418 | doi = 10.1111/j.1600-079X.1986.tb00759.x | s2cid = 41436917 }}{{cite journal |vauthors=Vilaplana J, Madrid JA, Sánchez-Vázquez J, Campuzano A, Cambras T, Díez-Noguera A | title = Influence of period length of light/dark cycles on the body weight and food intake of young rats. | journal = Physiology & Behavior | volume = 58 | issue = 1 | pages = 9–13 | year = 1995 | pmid = 7667433 | doi = 10.1016/0031-9384(95)00021-A | s2cid = 43118869 }}{{cite journal | vauthors = Lehrer S | title = Continuation of gradual weight gain necessary for the onset of puberty may be responsible for obesity later in life. | journal = Discovery Medicine | volume = 110 | issue = 110| pages = 191–196 | year = 2015 | pmid = 26562472 | doi= | pmc = 4809356 }}

An array of "autoamplification processes" increases the production of all of the pubertal hormones of the hypothalamus, pituitary, and gonads.{{Cite web |title=Sex Determination _ Dr Mahmoud Ahmad Fora |url=https://www.just.edu.jo/~mafika/733_Reproductive%20Endocrinology/Puberty_733.htm |access-date=2022-07-06 |website=www.just.edu.jo}}

• adrenarche (approximately ages 6—8)
• gonadarche (approximately age 10½ in females and age 11½ in males)
• thelarche (approximately age 10½ in females)
• pubarche (approximately age 11 in females and age 12 in males)
• menarche (approximately age 12½ in females)
• spermarche (approximately age 13 in males{{cite journal |title=Edad de aparición de la espermaturia (espermaquia) en 669 niños mexicanos y su relación con caracteres sexuales secundarios y talla |trans-title=Age of onset of spermaturia (spermache) in 669 Mexican children and its relation to secondary sexual characteristics and height |journal=Boletin Medico del Hospital Infantil de Mexico |volume=49 |issue=1 |pages=12–17 |pmid=1304761 |vauthors=Guízar-Vázquez JJ, Rosales-López A, Ortiz-Jalomo R, Nava-Delgado SE, Salamanca-Gómez F |date=1992 |language=es}})

{{Div col|colwidth=18em}}

• Adolescent sexuality
• Child sexuality
• Menopause
• Andropause
• Delayed puberty
• Eunuch
• Hebephilia
• Kallmann syndrome
• Precocious puberty
• Puberphonia
• Puberty blocker
• Seclusion of girls at puberty
• Secondary sex characteristic

{{Div col end}}

{{Reflist|colwidth=30em}}

{{Refbegin}}

• {{Cite book | vauthors=Gordon CM, Laufer MR | veditors = Emans SJ, Goldstein DP, Laufer MR | title = Pediatric and Adolescent Gynecology | edition = 5th | year = 2005 | publisher = Lippincott Williams & Wilkins | location = Philadelphia | isbn = 978-0-7817-4493-5 | pages = 120–155 | chapter = Chapter 4: Physiology of puberty }}
• {{Cite book | vauthors=Gungor N, Arslanian SA | veditors = Sperling MA | title = Pediatric Endocrinology | edition = 2nd | year = 2002 | publisher = Saunders | location = Philadelphia | isbn = 978-0-7216-9539-6 | pages = 689–724 | chapter = Chapter 21: Nutritional disorders: integration of energy metabolism and its disorders in childhood | chapter-url = https://archive.org/details/pediatricendocri00mark/page/689 }}
• {{Cite journal| doi = 10.2307/2532505| issn = 0006-341X| volume = 47| issue = 1| pages = 177–193| last1 = Jorgensen| first1 = Merete| last2 = Keiding| first2 = Niels| last3 = Skakkebaek| first3 = Niels Erik| title = Estimation of Spermarche from Longitudinal Spermaturia Data| journal = Biometrics| access-date = 2023-03-03| date = 1991| url = https://www.jstor.org/stable/2532505| jstor = 2532505| pmid = 2049498}}
• {{Cite book | vauthors=Marshall WA, Tanner JM | veditors = Falkner F, Tanner JM | title = Human Growth: A Comprehensive Treatise | edition = 2nd | year = 1986 | publisher = Plenum Press | location = New York | isbn = 978-0-306-41952-2 | pages = 171–209 | chapter = Chapter 8: Puberty | chapter-url = https://archive.org/details/humangrowthcompr0001unse/page/171 }}
• {{Cite book | last = Rosenfield | first = Robert L. | editor = Sperling, MA | title = Pediatric Endocrinology | edition = 2nd | year = 2002 | publisher = Saunders | location = Philadelphia | isbn = 978-0-7216-9539-6 | pages = 455–518 | chapter = Chapter 16: Female puberty and its disorders | chapter-url = https://archive.org/details/pediatricendocri00mark/page/455 }}
• {{Cite book | last = Styne | first = Dennis M. | editor = Sperling, MA | title = Pediatric Endocrinology | edition = 2nd | year = 2002 | publisher = Saunders | location = Philadelphia | isbn = 978-0-7216-9539-6 | pages = 565–628 | chapter = Chapter 18: The testes: disorders of sexual differentiation and puberty in the male | chapter-url = https://archive.org/details/pediatricendocri00mark/page/565 }}

{{Refend}}

{{Refbegin}}

• {{cite journal |last1=Avila |first1=Jonathan T. |title=Normal adolescent growth and development |journal=Encyclopedia of Child and Adolescent Health (First Edition) |publisher=Academic Press |date=2023 |volume=1 |pages=735–745 |doi=10.1016/B978-0-12-818872-9.00011-X |isbn=978-0-12-818873-6 |url=https://www.sciencedirect.com/science/article/abs/pii/B978012818872900011X}}
• {{cite book|last1=Colborn|first1=Theo|last2=Dumanoski|first2=Dianne|last3=Myers|first3=John Peterson|title=Our Stolen Future|year=1996|publisher=Little, Brown|isbn=0316875465}}
• Ducros, A. and Pasquet, P. "Evolution de l'âge d'apparition des premières règles (ménarche) en France". Biométrie Humaine (1978), 13, 35–43.
• {{cite journal | vauthors = Gluckman PD, Hanson MA | title = Evolution, development and timing of puberty | journal = Trends in Endocrinology and Metabolism | volume = 17 | issue = 1 | pages = 7–12 | year = 2006 | pmid = 16311040 | doi = 10.1016/j.tem.2005.11.006 | s2cid = 26141301 }}
• {{cite journal |vauthors=Herman-Giddens ME, Slora EJ, Wasserman RC, Bourdony CJ, Bhapkar MV, Koch GG, Hasemeier CM | title = Secondary sexual characteristics and menses in young girls seen in office practice: a study from the Pediatric Research in Office Settings network. | journal = Pediatrics | volume = 99 | issue = 4 | pages = 505–12 | year = 1997 | pmid = 9093289 | doi = 10.1542/peds.99.4.505 }} Newer data suggesting that lower age thresholds for evaluation should be used.
• Plant TM, Lee PA, eds. The Neurobiology of Puberty. Bristol: Society for Endocrinology, 1995. Proceedings of the latest (4th) International Conference on the Control of the Onset of Puberty, containing summaries of current theories of physiological control, as well as GnRH analog treatment.
• Sizonenko, PC. [http://sites.google.com/site/pcsizonenko/ Role of sex steroids during development—integration] {{Webarchive|url=https://web.archive.org/web/20130704134313/https://sites.google.com/site/pcsizonenko/ |date=2013-07-04 }}. in Bourguignon, Jean Pierre & Tony M. Plant. The Onset of Puberty in Perspective: Proceedings of the 5th International Conference on the Control of the Onset of Puberty, Held in Liège, Belgium, 26–28 September 1999. Elsevier. Amsterdam & New York 2000. {{ISBN|0-444-50296-3}}. pp 299–306.
• {{cite journal |vauthors=Tanner JM, Davies PS | title = Clinical longitudinal standards for height and height velocity for North American children. | journal = The Journal of Pediatrics | volume = 107 | issue = 3 | pages = 317–29 | year = 1985 | pmid = 3875704 | doi = 10.1016/S0022-3476(85)80501-1 }} Highly useful growth charts with integrated standards for stages of puberty.
• {{cite journal | vauthors = Terasawa E, Fernandez DL | title = Neurobiological mechanisms of the onset of puberty in primates | journal = Endocrine Reviews | volume = 22 | issue = 1 | pages = 111–51 | year = 2001 | pmid = 11159818 | doi = 10.1210/edrv.22.1.0418 | doi-access = free }}
• [https://www.sciencedaily.com/releases/2005/12/051201022811.htm "Research shows how evolution explains age of puberty"], ScienceDaily, December 1, 2005

{{Refend}}

{{sisterlinks|d=Q101065|c=Category:Puberty|n=no|b=no|q=no|v=no|voy=no|m=no|mw=no|s=Puberty|wikt=no|species=no}}

• [https://web.archive.org/web/20100514190953/http://www.theteencentre.com/forums/ Support for teens] (archive)
• [https://web.archive.org/web/20130924134845/http://umm.edu/health/medical/ency/articles/puberty-and-adolescence University of Maryland guide to puberty and adolescence]
• [http://www.sexarchive.info/GESUND/ARCHIV/GUS/INDEXATLAS.HTM Growing Up Sexually: A World Atlas]
• [http://www.007b.com/breast_development.php Pictures and detailed information about breast development during puberty]
• [https://web.archive.org/web/20180330032048/http://www.aboutkidshealth.ca/En/HowTheBodyWorks/SexDevelopmentAnOverview/SexualDifferentiation/Pages/PubertyinGirls.aspx Puberty in females: interactive animation of Tanner stages]
• [https://web.archive.org/web/20180321125947/http://www.aboutkidshealth.ca/En/HowTheBodyWorks/SexDevelopmentAnOverview/SexualDifferentiation/Pages/PubertyinBoys.aspx Puberty in males: interactive animation of Tanner stages]

{{Reproductive physiology}}

{{Humandevelopment}}

{{Authority control}}

Category:Adolescence

Category:Human development

Category:Human female endocrine system

Category:Sexuality and age