1. 1 INTRODUCTION TO PUBERTY Puberty is the process of physical changes by which a child’s body becomes an adult body capable of reproduction, it is the time at which a growing boy or girl begins the process of sexual maturation. At puberty, a young man’s body begins making sperm and he starts to be able to ejaculate, which is Semen coming out from his penis when he is sexually excited. If he has sexual intercourse (sex) with a young woman, he can make her pregnant.In a strict sense, the term puberty (derived from the Latin word puberatum (age of maturity, manhood)) refers to the bodily changes of sexual maturation rather than the psychosocial and cultural aspects of adolescent development. Adolescence is the period of psychological and social transition between childhood and adulthood. Adolescence largely overlaps the period of puberty, but its boundaries are less precisely defined and it refers as much to the psychosocial and cultural characteristics of development during the teen years as to the physical changes of puberty.

Puberty involves a series of physical stages or steps that lead to the achievement of fertility and the development of secondary sex characteristics, the physical features associated with adult males and females (such as the growth of pubic hair). While puberty involves a series of biological, or physical, transformations, the process can also have an effect on the psychosocial and emotional development of the adolescent. Puberty is initiated by hormone (which are chemicals) signals from the brain to the gonads (the ovaries and testes).In response, the gonads produce a variety of hormones that stimulate the growth, function, or transformation of brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Growth accelerates in the first half of puberty and stops at the completion of puberty. Before puberty, body differences between boys and girls are almost entirely restricted to the genitalia. During puberty, major differences of size, shape, composition, and function develop in many body structures and systems.The most obvious of these are referred to as secondary sexual characteristics.

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People all over the world start puberty at different ages. Changes that happen to young men and women during puberty include the sex organs growing bigger, hair appearing on the body, and growing taller and stronger. People often notice young men’s voices getting deeper, and young women growing breasts and starting to menstruate (have periods). Puberty causes:Physical changes, such as rapid growth spurts, the development of breasts in girls and an increase in penis size in boys Psychological changes that can cause teenagers to become moody, self-conscious and aggressive Behavioural changes that can cause some teenagers to experiment with new and potentially risky activities, such as smoking, drinking, alcohol and sex.

Because puberty is the time in a child’s life when he or she becomes able to make children, this is seen as very important. Therefore, people in many countries around the world have different ways of marking this event. .

2 DEFINITION OF PUBERTY Puberty is the period or age at which a person is first capable of sexual reproduction of offspring: in common law, presumed to be 14 years in the male and 12 years in the female. 1. 3 ONSET OF PUBERTY On average, girls start puberty between the ages of 9 and 14 years, and boys start between 10 and 17 years. However, just because a person’s puberty does not start during these ages does not mean they are not normal. [William and Tanner (1986)] People from all over the world start puberty at different ages.This is because of their environment (things around them), and maybe even events in their lives. [Giannini and Slaby, 1981. ] The timing of the onset of puberty is not completely understood and is likely determined by a number of factors.

One theory proposes that reaching a critical weight or body composition may play a role in the onset of puberty. It has been proposed that the increase in childhood obesity may be related to the overall earlier onset of puberty in the general population in recent years. (M Johnson, 2007). CHAPTER 2 VARIATIONS 2. TIMING OF THE ONSET OF PUBERTY The definition of the onset of puberty depends on perspective (e. g. hormonal versus physical) and purpose (establishing population normal standards, clinical care of early or late pubescent individuals, etc.

). The most commonly used definition of the onset of puberty is physical changes to a person’s body [Chumlea, 1982]. 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. [Kaplowitz et al,. 2001).

] An example of social circumstances is the Vandenbergh effect; a juvenile female who has significant interaction with adult males will enter puberty earlier than juvenile females who are not socially overexposed to adult males. [Nelson, 2005). ] The average age at which puberty begins may be affected by race as well.


[Zuckerman and Diana, 2009 ] 2. 2 HISTORICAL SHIFT The average age at which the onset of puberty occurs has dropped significantly since the 1840s. Whincup et al,. 2001] Researchers refer to this drop as the ‘secular trend’. In every decade from 1840 to 1950 there was a drop of four months in the average age of menarche among Western European females. In Norway, girls born in 1840 had their menarche at an average age of 17 years.

In France the average in 1840 was 15. 3 years. In England the average in 1840 was 16. 5 years. In Japan the decline happened later and was then more rapid: from 1945 to 1975 in Japan there was a drop of 11 months per decade. A 2006 study in Denmark found that puberty, as videnced 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 girls at greater long-term risk of breast cancer. [BBC News.

2001-05-03. Retrieved 2007-08-02] 2. 3 GENETIC INFLUENCE AND ENVIRONMENTAL FACTOR Various studies have found direct genetic effects to account for at least 46% of the variation of timing of puberty in well-nourished populations. [Mustanski et al. 2004], The genetic association of timing is strongest between mothers and daughters.

The specific genes affecting timing are not yet known. [Ge et al. , 2007 ] Among the candidates is an androgen receptor gene. [Comings et al. , 2002 ] Researchers [Diana, 2001 ] 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. If genetic factors account for half of the variation of pubertal timing, environment factors are clearly important as well.

One of the first observed environmental effects is that puberty occurs later in children raised at higher altitudes. The most important of the environmental influences is clearly nutrition, but a number of others have been identified, all which affect timing of female puberty and menarche more clearly than male puberty. [Mustanski et al. , 2004 ] 2. 4 HORMONES AND STEROIDS There is theoretical concern, and animal evidence, that environmental hormones and chemicals may affect aspects of prenatal or postnatal sexual development in humans. Dumanoski and Myers 1996 ] Large amounts of incompletely metabolized estrogens and progestagens from pharmaceutical products are excreted into the sewage systems of large cities, and are sometimes detectable in the environment. Sex steroids are sometimes used in cattle farming but have been banned in chicken meat production for 40 years.

Although agricultural laws regulate use to minimize accidental human consumption, the rules are largely self-enforced in the United States. Significant exposure of a child to hormones or other substances that ctivate estrogen or androgen receptors could produce some or all of the changes of puberty. More obvious degrees of partial puberty from direct exposure of young children to small but significant amounts of pharmaceutical sex steroids from exposure at home may be detected during medical evaluation for precocious puberty, but mild effects and the other potential exposures outlined above would not. [Dumanoski and Myers 1996 ] 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 behavioural effects on foetuses, infants, and children at current exposure levels because it can affect the prostate gland, mammary gland, and lead to early puberty in girls. BPA mimics and interferes with the action of oestrogen-an important reproduction and development regulator.

It leaches out of plastic into liquids and foods, and the Centres 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. [Dumanoski and Myers 1996 ] 2. 5 NUTRITIONAL INFLUENCE Nutritional factors are the strongest and most obvious environmental factors affecting timing of puberty. [Ge, Xiaojia; Natsuaki, Misaki N.

; Neiderhiser, Jenae M. ; Reiss, David (2007). ] Girls are especially sensitive to nutritional regulation because they must contribute all of the nutritional support to a growing fetus.Surplus calories (beyond growth and activity requirements) are reflected in the amount of body fat, which signals to the brain the availability of resources for initiation of puberty and fertility. Much evidence suggests that for most of the last few centuries, nutritional differences accounted for majority of variation of pubertal timing in different populations, and even among social classes in the same population. Recent worldwide increased consumption of animal protein, other changes in nutrition, and increases in childhood obesity have resulted in falling ages of puberty, mainly in those populations with the higher previous ages.In many populations the amount of variation attributable to nutrition is shrinking.


, 2007 ] 2. 6 OBESITY INFLUENCE AND EXERCISES Scientific researchers have linked early obesity with an earlier onset of puberty in girls.They have cited obesity as a cause of breast development before nine years and menarche before twelve years. Early puberty in girls can be a harbinger of later health problems. [McKenna and Phil, 2007 ] The average level of daily physical activity has also been shown to affect timing of puberty, especially in females. A high level of exercise, whether for athletic or body image purposes, or for daily subsistence, reduces energy calories available for reproduction and slows puberty. The exercise effect is often amplified by a lower body fat mass and cholesterol.

[McKenna and Phil, 2007] 2. PHYSICAL AND MENTAL ILLNESS Chronic diseases can delay puberty in both boys and girls. Those that involve chronic inflammation or interfere with nutrition have the strongest effect.

In the western world, inflammatory bowel disease and tuberculosis have been notorious for such an effect in the last century, while in areas of the underdeveloped world, chronic parasite infections are widespread. 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.Girls aged between 15 and 19 make up 40% of anorexia nervosa cases. [Bulik et al.


(Mustanski et al. 2004). The most important part of a child’s psychosocial environment is the family, and most of the social influence research has investigated features of family structure and function in relation to earlier or later female puberty. Most of the studies have reported that menarche may occur a few months earlier in girls in high-stress households, whose fathers are absent during their early childhood, who have a stepfather in the home, who are subjected to prolonged sexual abuse in childhood, or who are adopted from a developing country at a young age.Conversely, menarche may be slightly later when a girl grows up in a large family with a biological father present. (Mustanski et al.

, 2004). More extreme degrees of environmental stress, such as wartime refugee status with threat to physical survival, have been found to be associated with delay of maturation, an effect that may be compounded by dietary inadequacy. (Mustanski et al.

, 2004). Most of these reported social effects are small and our understanding is incomplete. Most of these “effects” are statistical associations revealed by epidemiologic surveys.Statistical associations are not necessarily causal, and a variety of covariables and alternative explanations can be imagined. Effects of such small size can never be confirmed or refuted for any individual child. Furthermore, interpretations of the data are politically controversial because of the ease with which this type of research can be used for political advocacy. Accusations of bias based on political agenda sometimes accompany scientific criticism. (Mustanski et al.

, 2004).Another limitation of the social research is that nearly all of it has concerned girls, partly because female puberty requires greater physiologic resources and partly because it involves a unique event (menarche) that makes survey research into female puberty much simpler than male. (Mustanski et al. , 2004). CHAPTER 3 3. 1 HORMONAL CHANGES DURING PUBERTY Puberty in boys and girls starts when their bodies start making a lot of gonadotropin-releasing hormone (GnRH). [Plant et al,.

2007]. Scientists do not know for sure what causes the body to do this.However, they have noticed that puberty begins when girls weigh about 47 kilograms (104 lb) and boys weigh about 55 kilograms (121 lb). This suggests that the body is told to make a lot of GnRH by a hormone called leptin, which is made by fat tissue. [Meister et al,. 2001] People whose bodies have problems with leptin do not go through puberty. [ Clayton et al,. 2000] Leptin, a hormone produced by fat cells (adipocytes) in the body, has been suggested as a possible mediator of the timing of puberty.

In studies, animals deficient in leptin did not undergo puberty, but puberty began when leptin was administered to the animals.Further, girls with higher concentrations of the hormone leptin are known to have an increased percentage of body fat and an earlier onset of puberty than girls with lower levels of leptin. The concentration of leptin in the blood is known to increase just before puberty in both boys and girls. (Johnson, 2007). 3.

1. 1 HORMONAL CHANGES IN BOYS Early stages of male hypothalamic maturation seem to be very similar to the early stages of female puberty, though occurring about 1–2 years later. LH stimulates the Leydig cells of the testes to make testosterone and blood levels begin to rise.For much of puberty, nighttime levels of testosterone are higher than daytime. Regularity of frequency and amplitude of gonadotropin pulses seems to be less necessary for progression of male than female puberty.

(Sizonenko and Aubert ,1986) However, a significant portion of testosterone in adolescent boys is converted to estradiol. Estradiol mediates the growth spurt, bone maturation, and epiphyseal closure in boys just as in girls. Estradiol also induces at least modest development of breast tissue (gynecomastia) in a large proportion of boys.Boys who develop mild gynecomastia or even developing swellings under nipples during puberty are told the effects are temporary in some male teenagers due to high levels of estradiol. (Sizonenko and Aubert ,1986) Another hormonal change in males takes place during the teenage years for most young men. At this point in a males life the testosterone levels slowly rise, and most of the effects are mediated through the androgen receptors by way of conversion dihydrotestosterone in target organs (especially that of the bowels). Sizonenko and Aubert ,1986) 3.

1. 2 HORMONAL CHANGES IN GIRLS As the amplitude of LH pulses increases, the theca cells of the ovaries begin to produce testosterone and smaller amounts of progesterone. Much of the testosterone moves into nearby cells calledgranulosa cells. Smaller increases of FSH induce an increase in the aromatase activity of these granulosa cells, which converts most of the testosterone to estradiol for secretion into the circulation.Rising levels of estradiol produce the characteristic estrogenic body changes of female puberty: growth spurt, acceleration of bone maturation and closure, breast growth, increased fat composition, growth of the uterus, increased thickness of the endometrium and the vaginal mucosa, and widening of the lower pelvis. (Sizonenko and Aubert ,1986) As the estradiol levels gradually rise and the other autoamplification processes occur, a point of maturation is reached when the feedback sensitivity of the hypothalamic “gonadostat” becomes positive.This attainment of positive feedback is the hallmark of female sexual maturity, as it allows the mid cycle LH surge necessary for ovulation.

Levels of adrenal androgens and testosterone also increase during puberty, producing the typical androgenic changes of female puberty: pubic hair, other androgenic hair as outlined above, body odor, acne. 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. (Sizonenko and Aubert , 1986) 3. HOW THE BODY CONTROLS PUBERTY The location of the pituitary gland is shown in red. The gland makes hormones that cause males’ and females’ bodies to start puberty.

Puberty is started and carried on by different hormones. Hormones are chemicals that tell parts of the body to do things. Hormones are made by glands in the body. Glands are organs (special parts) of the body that make hormones. This is what happens during puberty: [ Steven, 2007. ] 1. A gland at the bottom of the brain called the hypothalamus sends gonadotropin-releasing hormone (GnRH) into a nearby gland called the pituitary gland.

. GnRH causes cells in the pituitary gland to make two hormones, luteinizing hormone (LH) and follicle stimulating hormone (FSH). LH and FSH are types of hormones called gonadotropins. The bloodstream carries these hormones around the body. 3. LH and FSH make the gonads grow larger and start producing their own hormones, estradiol and testosterone. A girl’s gonads are her ovaries, and a boy’s gonads are his testicles (also called testes). Both ovaries and testicles produce estradiol and testosterone, but ovaries produce more estradiol and testicles produce more testosterone.

Estradiol and testosterone are types of hormones called steroid hormones. Steroid hormones are also made by the body’s two adrenal glands, which sit on top of the two kidneys. 4. When the amount of estradiol and testosterone in the body increases, various parts of the body change. [Plant, 2001. ] Also, a gene has been identified that appears to be critical for the normal development of puberty.

The gene, known as GPR54, encodes a protein that appears to have an effect on the secretion of GnRH by the hypothalamus. [Plant, 2001. ] Here are some of the things that make puberty happen at different ages in people: •Genetics.Genetics is the study of how parents pass on to their children some of the way they are through their genes. Half of a person’s genes come from the mother. The other half come from the father.

Some studies have found that mothers and daughters tend to start puberty at about the same age. [Xiaojia et al,. 2007. ] •Diet. Boys and girls who have a good diet – who eat healthy food – tend to start puberty earlier.

[Xiaojia et al,. 2007. ] Today, people start puberty younger than in the 1840s. For example, in Norway, girls born in 1840 had their first period at an average age of 17 years; in France the average age was 15. years; and in England it was 16. 5 years. [Harry, 2003. ] This may be because people have better food to eat today.


This is thought to be because their bodies use up the food that they eat faster. This causes them to have less body fat, so there is less leptin to tell their brains to start puberty. •Obesity. Obesity is the state of being very overweight. A scientific study seems to say that girls who are obese start puberty early.Some obese girls have started growing breasts before the age of nine years and have had their first period before 12 years.


[Molly, 2007] •Illness. Boys and girls who are sick for a long time, especially with illnesses that cause them to have a poor diet, tend to start uberty late. For example, this often happens to people who suffer from anorexia nervosa.


[Diana et al,. 2008 ] •Stress. It is thought that people who are under a lot of stress start puberty later.Some research seems to show that girls have their first period a bit later when their fathers are not around when they are young, when they have a stepfather, if they have been sexually abused for a long time, or if they were adopted by their parents from another country at a young age. On the other hand, the first period may happen a bit later when a girl grows up in a large family with her natural father around. However, scientists are not sure how correct these studies are. Not many studies have been done to find out if stress also causes boys to start puberty later. [Abbassi, 1998] •Chemicals.

Some scientists think people may start puberty earlier because their bodies are affected by chemicals such as estrogens and progestagens that are put in the environment by humans. Another chemical that may cause early puberty is Bisphenol A (BPA). It is used to make plastics, such as some types of baby bottles, water bottles and sports equipment. [Diana et al,. 2008] Girls usually reach their adult height and become sexually mature (able to have babies) about four years after puberty starts. Boys grow for about six years after puberty starts. Puberty in boys starts off more slowly than in girls, but then speeds up later on.

Although boys are usually about 2 centimetres (0. 8 in) shorter than girls before puberty begins, adult men on average end up about 13 centimetres (5. 1 in) taller than women. [Abbassi, 1998] 3. 3 PHYSICAL CHANGES 3.

3. 1 PHYSICAL CHANGES IN BOYS For most boys, puberty takes about six years and ends when they are about 17 or 18 years old. At the end of puberty, a teenager is usually about 10 to 30 centimetres (cm) (4 to 12 inches (in)) taller, 7 to 29 kilograms (kg) (15 to 65 pounds (lb)) heavier, and stronger. He is also able to make a woman pregnant (have a baby). [Ann, 2007)] Sex organs grow biggerDuring puberty, a young man’s penis and testicles grow bigger, and he starts ejaculating semen. Hair also begins to grow on his body. The first sign of puberty in boys is that their testicles (also called the testes) and scrotum (the “bag” that the testicles are in) grow bigger.

[Dennis, 2002. ] Before puberty, each testicle is about 1. 5 to 2 cm (0. 6 to 0.

8 in) long and has avolume of about 2 to 3 cubic centimetres (cc) (0. 1 to 0. 2 cubic inches (cu in)). About six years after puberty starts, the testicles reach their adult size. [Kenneth, 2006] The volume of an average adult man’s testicle is about 18 to 20 cc (1. 1 to 1. 2 cu in).However, it is normal for some men to have testicles smaller than this size, and for other men to have larger testicles.

[Marshall, 1986] The penis also grows bigger during puberty. At the start of puberty, the average length of the penis is 6 cm (2. 4 in).

The penis reaches adult size about five years later. [Kenneth, 2006 ] A study done in 1996 found the mean length of an adult man’s penis is 3. 5 in (8. 9 cm) when it is flaccid (pronounced [? fl? s? d], FLA-sid) (not erect or hard). The average length of an erect penis is about 12.

9 to 15 cm (5. 1 to 5. 9 in). [Kenneth, 2006 ] The testicles have two main jobs: to make hormones and sperm.



[Marshall, 1986] These glands make a lot of the liquid that is in semen. When a man is sexually excited, he gets an erection – his penis becomes bigger, longer and harder. A male can become sexually excited if thinks about sex or sees a good-looking person, or if his penis rubs against something. During puberty, some boys also have spontaneous erections.These are erections that happen by themselves without any reason.

This can be embarrassing when it happens in a public place. [Marshall, 1986]. When a man’s penis is sexually stimulated for some time, he has an orgasm and semen shoots out from the penis. This is called ejaculation.

Young boys cannot ejaculate. A boy’s first ejaculation usually happens about one year after he begins puberty. For some boys, the first ejaculation takes place when they are sleeping. This is called a nocturnal emission or a wet dream. It happens without the boy’s control, often when he is having a dream about sex.Scientists believe that wet dreams are the body’s way of removing too much semen.

A study done of 5,300 white men in the United States in 1948 [Marshall, 1986] found that 13% of them had their first ejaculation through a wet dream, [Marshall, 1986] This seems to tell us that most boys have their first ejaculation after masturbating. A male masturbates when he rubs his penis to make himself feel good sexually. The study also found that most boys who have their first ejaculation by masturbating do this a year or more earlier than boys who have their first ejaculation through a wet dream. Marshall, 1986] A 2004 survey by a magazine in Canada found that most males (43%) started masturbating when they were about 12 to 13 years old.

[Marshall, 1986] When a boy begins masturbating, wet dreams often stop happening because semen is taken out from his body regularly. When a boy starts to ejaculate, he usually produces only a small amount of semen. The semen is different from what an adult man produces. It is usually clear and stays sticky. It either has no sperm in it, or sperm that do not move properly or do not move at all. A boy’s semen only becomes like an adult man’s semen about two years after his first ejaculation. Marshall, 1986] Body hair and skin changes This picture shows how hair grows on a male body during and after puberty During puberty, hair starts appearing on the face Not long after a boy’s testicles and penis start to grow, pubic hair (pronounced [? pju? bik], PEW-bik) begins to appear. Pubic hair is hair that grows in the pubic region, which is the part of the body where the penis is.

Pubic hair is shorter, curlier and rougher than hair on the head. It usually starts growing on the abdomen above the penis at the place where it joins the body. (The abdomen is the part of the torso where the navel or bellybutton is. There may also be some hair on the scrotum. After about six months to a year, there will be a large triangle of hair in the pubic region. Within three to four years after puberty begins, there is a lot of pubic hair in the area above the penis. Later on, pubic hair also grows on the abdomen upwards towards the navel and on the insides of the thighs. [Clayton and Trueman, 2000 ] About two years after pubic hair starts to appear, [Clayton & Trueman, 2000 ], hair also grows on other parts of the body: •In the armpits.

•Around the anus. •On the upper lip, forming a mustache (also spelled moustache in the United Kingdom and other countries). On the sides of the face in front of the ears, forming sideburns.

•Around the nipples. •On the lower part of the face, forming a beard. The hair on the arms, legs, chest, abdomen and back may also become thicker. Different men have different amounts of body hair. Many boys begin shaving when hair starts growing on their faces.

A larger amount of male hormones in the body cause changes to perspiration (sweat). This gives it a more “adult” body odor or smell. The hormones also cause sebaceous glands in the skin to make more sebum, a type of oil that keeps the skin from getting too dry.Sebum and dead skin cells can mix with a type of germ called bacteria and block pores (tiny openings) in the skin. This causes a skin problem called acne. Most people get acne during puberty. When a person has acne, he gets swellings on his skin called blackheads, whiteheads and pimples. Blackheads and whiteheads are painless, but pimples can be red and painful.

They usually form on the face but can also appear on the neck, shoulders, upper back and chest. Oil glands on scalp – the part of the head on which hair grows – also make a lot of sebum. This can cause dandruff, in which small white bits of skin fall from the scalp. Clayton and Trueman, 2000 ] Voice changes During puberty, a boy’s larynx or voice box also grows larger.

This makes the laryngeal prominence or Adam’s apple – the lump that sticks out of the front of his neck – larger too. As the larynx grows the vocal chords become longer and thicker, so they vibrate (move back and forth) more slowly. This causes the voice to lower in pitch or tone and become deeper. When this happens, it is sometimes said that the boy’s voice has “broken”. However, it actually does not happen overnight but over some time. During this time, the voice may sound scratchy.

On average, a boy’s voice normally reaches its adult sound when he is around 15 years old. [Clayton and Trueman, 2000 ] Body growth Towards the end of puberty, boys go through a “growth spurt” which lasts for about two to three years. During this time, their body grows taller very quickly. When the growth spurt is at its fastest point, some people grow 10 cm (4 in) or more a year. This happens about two years after puberty starts, usually between the ages of 13 and 15. When a boy reaches the end of his growth spurt when he is about 18 years old, he will be at his adult height.

His body will not grow much taller after that. Steven, 2007] Because of their growth spurt, boys’ muscles can feel sore. These “growing pains” can feel worse if boys are active and do a lot of exercise.

They go away after a while. Boys grow more slowly than girls, but for a longer time. That is why most men are taller than women. [Steven, 2007] In the male body, some of the hormone testosterone is changed into another hormone called estradiol. Estradiol sometimes causes boys to grow small breasts. This is called gynecomastia. Scientists think that about half of all boys have gynecomastia in one or both sides of the chest. Steven, 2007] There can be some swelling and pain.

The growth usually disappears by the end of puberty. However, if the breast growth is very obvious (which may happen if the person is overweight) and is causing him a lot of worry, it can be removed by surgery. [Steven, 2007] During the later part of puberty, boys also go through a “strength spurt” during which their muscles grow quickly. The strength spurt is fastest about a year after the fastest point of the growth spurt. By the end of puberty, adult males have heavier bones and more muscle than females.In an average adult man, muscle makes up 50% and fat 15% of his weight. On the other hand, 40% of an average adult woman’s weight is made up of muscle while 27% is made up of fat. Because men have less body fat than women, their hips do not grow bigger.

Some bones like those in the jaw and shoulders grow more in males than in females. That is why males have wider faces and shoulders but narrower hips. [Rosenfield, 2002] 3. 3. 2 PHYSICAL CHANGES IN GIRLS The changes in a girl’s body during puberty usually take place between the ages of eight and 18 years. Most girls will have finished puberty around the age of 15.They will have breasts and pubic hair, will menstruate (have a period) every month, and will be able to get pregnant. They will usually also have reached their full adult height.

[Jeff, 2008] Breasts grow The first sign of puberty that can be seen on the outside of a girl’s body is usually the breasts starting to grow. When the breasts start to grow, this is normally the first sign of puberty that can be seen on the outside of a girl’s body. This usually happens when girls are about the age of 10. 5 years.

A lump that is a bit hard appears in each breast under the areola, which is the dark ring around the nipple.The lump in one breast may grow before the other one. This is called breast budding. [Anne, 2007] Within six to 12 months, both breasts will have started growing.

The swelling can be felt and seen outside the edges of the areolae. About one and a half to two years after the breasts first start growing, they are close to the shape and size of an adult woman’s breasts. The nipple and areola may be on a smaller mound on each breast. This small mound usually goes away when each breast is fully grown. [Anne, 2007 ] Whether the breasts are small or large depends on how much fat there is in the body. Anne, 2007] Body hair and skin changes Between the ages of about eight and 14 (on average, at 11 or 12 years), pubic hair begins to grow along the labia (the “lips” of the vulva), usually a few months after the breasts start growing. [Tanner and Davies, 1985)] At first the hair is thin and straight instead of curly, and there is not much of it. [Tanner and Davies, 1985)] Within a year, the pubic hair becomes rough, dark and curly and grows in a triangle shape in the pubic region.

About one year after pubic hair begins appearing, underarm hair also grows.The hair on the arms and legs also gets thicker, and some girls may have hair appearing on their upper lip and in front of their ears. Like boys, higher amounts of hormones in the body cause girls’ perspiration (sweat) to change. This gives them a more adult body odour or smell.

The hormones also cause the skin to produce more sebum (oil), which usually leads to acne. [Tanner and Davies, 1985)] Changes to the sex organs and menstruation When girls are between eight and 11 years old, the two ovaries in their body begin to grow bigger. [Jeff, 2008] Each ovary is egg-shaped, and is attached to the side wall of the pelvis.The pelvis is a large set of bones in the hips.

The ovaries are organs that make female hormones. These hormones cause a girl to grow into a woman, and make her feel like a woman. The hormones also make it possible for females to become pregnant and have babies. Inside the ovaries are about 200,000 ova (egg cells). [Jeff, 2008] For a baby to be formed, a woman’s ovum and a man’s sperm must come together. During puberty, the ova also grow bigger.

[Marshall, 1986] Between the ages of nine and 15 years (on average, at 12 to 13 years), the vagina and uterus (womb) become bigger. Marshall, 1986] The uterus is the organ in which a baby grows. The vagina is a tube leading from the uterus to the outside of the body. The opening of the vagina is inside the vulva, in between the legs. A clear or whitish fluid may start to flow out of the vagina to keep it clean. [Marshall, 1986] Then, about two years after the breasts start to grow, [Tanner and Davies, 1985).



[Apter, 1980 ] The uterus then starts preparing for another ovum. For most girls, the time between their periods is about one month. For about two years after menstruation starts, the time between periods is not always the same. [Apter, 1980] Some girls may skip a month, or have two periods close to each other.

It is also normal to have cramps (rather painful squeezing feelings) or to feel bloated (swollen up) in the abdomen during periods. Apter, 1980] When many girls start having periods, they begin using sanitary napkins (also called sanitary pads) or tampons to soak up the blood and tissue. A sanitary napkin is a piece of material that is absorbent (able to take in liquids) which is worn between the vulva and underpants. A tampon is a stick of absorbent material that is placed inside the vagina. In 2004, a survey by a Canadian magazine found that most females (25%) started masturbating when they were about 12 to 13 years old.

[Alice, 2004] Body growth Because of more hormones in the body, girls start to have more fat in their breasts, abdomen, hips and thighs.At the age of ten years, the average girl has 6% more body fat than the average boy, but by the end of puberty the difference is nearly 50%. [Neslihan and Arslanian, 2002] The fat makes sure that a baby growing inside a pregnant woman will have enough nutrients. Also, the bones in the pelvis move further apart to make room for a larger uterus and ovaries, and so there is space for a baby to grow in the uterus and to pass out of the body when it is born. The extra fat and wider hip bones that girls have give them a curvier shape. [Apter, 1980] Girls also experience a growth spurt during puberty.

In the first year after puberty begins, they grow about 8 cm (3 in). They grow even faster the next year or so, and then the growth slows down and almost stops when they start menstruating. After a girl’s periods begin, she usually does not grow more than 5 cm (2 in) taller. [Marshall, 1986] 3. 4 EMOTIONAL CHANGES IN MALES AND FEMALES The large amounts of hormones in the bodies of boys and girls during puberty can also affect their emotions.


Therefore, it may be helpful for them to follow the advice of adults they trust, even if it does not make much sense to them at the time. [Apter, 1980] 3. 5 CULTUREAn Australian aboriginal photographed some time before 1911 Because puberty is the time in a child’s life when he or she becomes able to make children, this is seen as very important. Therefore, people in many countries around the world have different ways of marking this event Males •Australia.


In some Philippine tribes such as the Agta, a young man who reaches puberty is taught how to masturbate by an older man. The young man then masturbates at a ceremony in front of other people. These men that comes out from his penis is collected in a piece of animal skin. Later on, the young man wears this animal skin when he has sex with his wife as it is believed that this will help him have children.

[Tom, 2010] FemalesA young Navajo girl photographed around 1904 •America. Among the Navajo (pronounced [? n? v?? ho? ], NA-v? -hoe), who are a Native American people, a young woman who has had her first period goes through a four-day ceremony called Kinaalda which shows that she has changed from being a girl to a woman. The young woman’s mother combs her hair and ties it into a ponytail. The young woman’s family then sings a prayer, after which she puts on a dress made of a rug and jewellery made of turquoise and seashells. The young woman then runs as fast as she can towards the east, and turns around and runs home.She usually does this once in the morning and once in the evening every day during the ceremony. On the first night, the young woman does not go to sleep but stays awake while more prayers are sung.

During the ceremony, the young woman also stands straight or lies on the ground in front of her mother, and her mother passes her hands over the young woman’s body to make sure that she grows up beautiful. On the last day of the ceremony, the young woman does a final run; her mother passes her hands over her body one last time; and the young woman gives alkaan, a large cake made of maize (corn) that she has made, to her whole tribe to eat. Smith, 2006] •Brazil. Among the Urubu-Kaapor people of Brazil, South America, when a young woman has had her first period, she goes into a room in her home covered with palm leaves to spend time alone for a month.

She only eats cooked white cassava flour and white tortoise meat. She sleeps in a hammock (a type of bed made of rope that is hung above the floor) as it is believed that some magic will escape if her feet touch the ground. On the seventh day of her time alone, the young woman’s father cuts her hair very short.Her legs are scratched with the tooth of an agouti, which is an animal that looks like a guinea pig. Pieces of cloth are wrapped around the woman’s forehead and abdomen (tummy), and large ants are put inside the cloth. After the woman has been bitten by the ants a few times, the cloth is removed.



After this, the young women appear at an event attended by the chief and everybody in the town or village. Young men also come to choose women to marry. [David, 2010] CHAPTER 4 4.

1 TYPES OF PUBERTY We have two types of puberty: Precocious puberty and delayed puberty. 4. 2 PRECOCIOUS PUBERTY As a medical term, precocious puberty describes puberty occurring at an unusually early age. In most of these children, the process is normal in every respect except the unusually early age, and simply represents a variation of normal development.

In a minority of children, the early development is triggered by a disease such as a tumour or injury of the brain. Even in instances where there is no disease, unusually early puberty can have adverse effects on social behaviour and psychological development, can reduce adult height potential, and may shift some lifelong health risks. Central precocious puberty can be treated by suppressing the pituitary hormones that induce sex steroid production.

The term is used with several slightly different meanings that are usually apparent from the context.In its broadest sense, and often simplified as early puberty, “precocious puberty” sometimes refers to any physical sex hormone effect, due to any cause, occurring earlier than the usual age, especially when it is being considered as a medical problem. A common definition for medical purposes is onset before 8 years in girls or 9 years in boys (Dickerman et al. , 2004). 4. 2. 1 Types and causes Pubertas praecox is the Latin term used by physicians in the 19th century.

Early pubic hair, breast, or genital development may result from natural early maturation or from several other conditions. CentralIf the cause can be traced to the hypothalamus or pituitary, the cause is considered central. Causes can include: •Damage to the inhibitory system of the brain (due to infection, trauma, or irradiation) •hypothalamic hamartoma produces pulsatile gonadotropin-releasing hormone (GnRH) •Langerhans cell histiocytosis [McCune-Albright Syndrome] •Central precocious puberty can be caused by intracranial neoplasm, infection, trauma, hydrocephalus, and Angelman syndrome.

(Dickerman et al. , 2004). Bones can be considered older in individuals with early puberty. Early puberty is marked by growth hormone problems resulting from various brain disorders.Precocious puberty can make a child able to conceive when very young; the youngest mother on record is Lina Medina, who gave birth at the age of 5 years, 7 months and 21 days. [Antoniazzi and Zamboni, 2004] “Central precocious puberty (CPP) was reported in some patients with suprasellar arachnoid cysts (SAC) (Dickerman et al. , 2004). , and SCFE occurs in patients with CPP because of rapid growth and changes of growth hormone secretion.

[Yamato et al,. 2004] Peripheral Secondary sexual development induced by sex steroids from other abnormal sources is referred to as peripheral precocious puberty or precocious pseudopuberty.It typically presents as a severe form of disease with children.

Symptoms are usually as a sequelae from adrenal insufficiency (because of 21-hydroxylase deficiency or 17 hydroxylase deficiency, the former being more common) which includes and is not limited to: hypotension, electrolyte abnormalities, ambiguous genitalia in females, signs of virilisation in females. Blood tests will typically reveal high level of androgens with low levels of cortisol (Masse et al,. 2008) Causes can include: •gonadal tumors (such as arrhenoblastoma) •adrenal tumors •germ cell tumor •Exogenous hormones •Environmental exogenous hormonesAs treatment for another condition Research Many causes of early puberty are somewhat unclear, though girls who have a high-fat diet and are not physically active or are obese are more likely to physically mature earlier. (Tanner et al,. 1990) “Obese girls, defined as at least 10 kilograms (22 pounds) overweight, had an 80% chance of developing breasts before their ninth birthday and starting menstruation before age 12 – the western average for menstruation is about 12. 7 years. ” [McKenna and Phil, 2007]. Exposure to chemicals that mimic estrogen (known as xenoestrogens) is a possible cause of early puberty in girls.Bisphenol A is a xenoestrogen found in hard plastics that has been shown to affect sexual development. [Libertun et al,. 2009]. “Factors other than obesity, however, perhaps genetic and/or environmental ones, are needed to explain the higher prevalence of early puberty in black versus white girls. [Kaplowitz et al,. 2001] While more girls are increasingly entering puberty at younger ages, new research indicates that some boys are actually starting later (delayed puberty). [Cooney and Elizabeth, 2010]. High levels of beta-hCG in serum and cerebrospinal fluid observed in a 9-year-old boy suggest a pineal gland tumor.The tumor is called a chorionic gonadotropin secreting pineal tumor. Radiography and chemotherapy reduced tumor and beta-hCG levels normalized. [ Kuo et al,. 2006]. In a study using neonatal melatonin on rats, results suggest that elevated melatonin could be responsible for some cases of early puberty. (Esouifino et al,. 1987) 4. 2. 2 Clinical and social significance Medical evaluation is sometimes necessary to recognize the few children with serious conditions from the majority who have entered puberty early but are still medically normal.Early sexual development deserves evaluation because it may: induce early bone maturation and reduce eventual adult height indicate the presence of a tumor or other serious problem cause the child, particularly a girl, to become an object of adult sexual interest [McKenna and Phil, 2007] Early puberty is believed to put girls at higher risk of sexual abuse, unrelated to pedophilia because the child has developed secondary sex characteristics. “Imagine being eight or nine years old and having men hit on you because you have breasts.Grown women have enough trouble dealing with unwanted sexual advances – imagine being in the fourth grade,” stated a researcher. [McKenna and Phil, 2007] Early puberty also puts girls at a higher risk for teasing or bullying, mental health disorders and short stature as adults. [Caspi et al,. 1993] Girls as young as 8 are increasingly starting to menstruate, develop breasts and grow pubic and underarm hair; these “biological milestones” only typically occurred at 13 or older decades ago, Females of African ancestry are especially prone to early puberty, [Kaplowitz et al,. 001]. There are theories debating the trend of early puberty, but the exact causes are not known. “This is a review of what we know; it’s absolutely superb,” said Dr. Marion Kavanaugh-Lynch, an oncologist and director of the California Breast Cancer Research Program in Oakland, which directs tobacco tax proceeds to research projects. “The data indicates that if you get your first period before age 12, your risk of breast cancer is 50 percent higher than if you get it at age 16,” said the report’s author, a biologist and also a cancer survivor. For every year we could delay a girl’s first menstrual period, we could prevent thousands of breast cancers. ” Though boys face fewer problems upon early puberty than girls, early puberty is not always positive for boys; early sexual maturation in boys can be accompanied by increased aggressiveness due to the surge of hormones that affect them. Because they appear older than their peers, pubescent boys may face increased social pressure to conform to adult norms; society may view them as more emotionally advanced, despite the fact that their cognitive and social development may lag behind their appearance.Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors. [Ritter and Jim, 2000] 4. 2. 3 Diagnostic criteria Studies indicate that breast development in girls and pubic hair in girls and boys are starting earlier than in previous generations. [Kaplowitz et al,. 2001]. As a result, “early puberty” in children, particularly girls, as young as 9 and 10 is no longer considered abnormal, although it may be upsetting to parents [Ritter and Jim, 2000] and can be harmful to children who mature physically at a time when they are immature mentally. Diana, 2001] No single age limit reliably separates normal from abnormal processes in children today, but the following age thresholds for evaluation will minimize the risk of missing a significant medical problem: •Breast development in boys before appearance of pubic hair or testicular enlargement. •Pubic hair or genital enlargement (gonadarche) in boys with onset before 9. 5 years. •Pubic hair (pubarche) before 8 or breast development (thelarche) in girls with onset before 7 years. •Menstruation (menarche) in girls before 10 years. 4. 2. 4 Treatment One possible treatment is with anastrozole.Histrelin acetate (Supprelin LA), Triptorelin or Leuprolide, any GnRH agonists, may also be used. GnRH agonists stimulate the pituitary to release Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). However, when used regularly, GnRH agonists cause a decreased release of FSH and LH. GnRH produced by the hypothalamus is pulsatile, allowing for a physiologic release of FSH and LH. 4. 3 DELAYED PUBERTY Puberty is described as delayed puberty with exceptions when a boy or girl has passed the usual age of onset of puberty with no physical or hormonal signs that it is beginning.Puberty may be delayed for several years and still occur normally, in which case it is considered constitutional delay, a variation of healthy physical development. Delay of puberty may also occur due to malnutrition, many forms of systemic disease or to defects of the reproductive system (hypogonadism) or the body’s responsiveness to sex hormones. Normal timing Approximate mean ages for the onset of various pubertal changes are as follows. Ages in parentheses are the approximate 3rd and 97th percentiles for attainment. For example, less than 3% of girls have not yet achieved thelarche by 13 years of age.Developmental changes during puberty in girls occur over a period of 3 – 5 years, usually between 10 and 15 years of age. They include the occurrence of secondary characteristics beginning with breast development, the adolescent growth spurt, the onset of menarche – which does not correspond to the end of puberty – and the acquisition of fertility, as well as profound psychological modifications, The normal variation in the age at which adolescent changes occur is so wide that puberty cannot be considered to be pathologically delayed until the menarche has failed to occur by the age of 18 or testicular development by the age of 20. Traggiai and Stanhope, 2003) 4. 3. 1 Possible causes •Variation of normal (constitutional delay) In females, prolonged high level of physical exertion, e. g. from being an athlete •Systemic disease, e. g. Inflammatory bowel disease, chronic renal failure •Undernutrition e. g. anorexia nervosa, zinc deficiency •Hypothalamic defects and diseases e. g. Prader-Willi syndrome, Kallmann syndrome •Pituitary defects and diseases e. g. hypopituitarism Gonadal defects and diseases e. g. Turner syndrome, Klinefelter syndrome, Testicular failure due to mumps orchitis, Coxsackievirus B, irradiation, chemotherapy, or trauma.Testicular failure is treated with testosterone replacement. , [Marianne et al,. 2004] Absence or unresponsiveness of target organs e. g. androgen insensitivity syndrome, mullerian agenesis Other hormone deficiencies and imbalances, Endocrine disorders. [Francis et al,. 2004] e. g. hypothyroidism, Cushing’s syndrome Cystic fibrosis [Johannesson et al,. 1997] Mutations in FSHB [Layman et al,. 1997] Frasier syndrome [Chan et al,. 2006] Various forms of congenital adrenal hyperplasia.Gonadotropin, a deficiency resulting from a number of congenital and acquired abnormalities of the central nervous system Biedl-Bardet syndrome Brain tumors e. g. craniopharyngioma, prolactinoma, germinoma, glioma; diseases of hypothalamus, irradiation and trauma. Constitutional delay Children who are healthy but have a slower rate of physical development than average have constitutional delay in growth and adolescence. These children have a history of stature shorter than their age-matched peers throughout childhood, but their height is appropriate for bone age, and skeletal development is delayed more than 2. SD. They usually are thin and often have a family history of delayed puberty. Children with a combination of a family tendency toward short stature and constitutional delay are the most likely to seek evaluation. They quite often seek evaluation when classmates or friends undergo pubertal development and growth, thereby accentuating their delay. 4. 3. 2 Medical evaluation Pediatric endocrinologists are the physicians with the most training and experience evaluating delayed puberty.A complete medical history, review of systems, growth pattern, and physical examination will reveal most of the systemic diseases and conditions capable of arresting development or delaying puberty, as well as providing clues to some of the recognizable syndromes affecting the reproductive system. Since bone maturation is a good indicator of overall physical maturation, an x-ray of the hand to assess bone age usually reveals whether the child has reached a stage of physical maturation at which puberty should be occurring. Visible secondary sexual development usually begins when girls achieve a bone age of 10. to 11 years, and boys achieve a bone age of 11. 5 to 12 years. The most valuable blood tests are the gonadotropins, because elevation confirms immediately a defect of the gonads or deficiency of the sex steroids. In many instances, screening tests such as a complete blood count, general chemistry screens, thyroid tests, and urinalysis may be worthwhile. More expensive and complicated tests, such as a karyotype or magnetic resonance imaging of the head, are usually obtained only when specific evidence suggests they may be useful. Use of gonadotropin releasing hormone can be of value in the differential diagnosis. Jungmann and Trautermann, 1994] 4. 3. 3 Management If a child is healthy but simply late, reassurance and prediction based on the bone age can be provided. No other intervention is usually necessary. In more extreme cases of delay, or cases where the delay is more extremely distressing to the child, a low dose of testosterone or estrogen for a few months may bring the first reassuring changes of normal puberty. If the delay is due to systemic disease or undernutrition, the therapeutic intervention is likely to focus mainly on those conditions.If it becomes clear that there is a permanent defect of the reproductive system, treatment usually involves replacement of the appropriate hormones (testosterone/dihydrotestosterone for boys, [ Saad et al,. 2001] estradiol and progesterone for girls). Pubertal delay due to gonadotropin deficiency is treated with testosterone replacement or with HCG [Marianne and Legato, 2004)] Growth hormone is another option that has been described. [Heinrichs et al,. 199 CHAPTER 5 5. 1 SUMMARY ••Puberty is the time of sexual maturation and achievement of fertility. •The time when puberty begins varies greatly among individuals; however, puberty usually occurs in girls between the ages of 10 and 14 and between the ages of 12 and 16 in boys. ••Body fat and/or body composition may play a role in regulating the onset of puberty. ••Puberty is associated with development of secondary sex characteristics and rapid growth. ••Some medical conditions may worsen or first become apparent at puberty. ••Precocious puberty is puberty that occurs earlier than usual. It is more common in girls than in boys. 5. 2 CONCLUSION 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 girl and 18 years for an average boy. Potential fertility (sometimes termed nubility) usually precedes completion of growth by 1–2 years in girls and 3–4 years in boys. Stage 5 typically represents maximal gonadal growth and adult hormone levels. 5. 3 RECOMMENDATION Both boys and girls can have a tough time when experiencing pubertal changes early.Make sure that your child knows that every individual in life undergoes the same changes but they occur earlier in some child and later in others. Encourage your child to take part in social activities and give them the chance to discuss their worries and feelings with you and finally always talk to your child when the need arises. References ?A. J. Giannini and A. E. Slaby (1981). “A Speculation on Puberty, Marriage Contracts and Frozen Food”; pp. 51–52. ?Abbassi, V (1998). “Growth and normal puberty. ”; Paediatrics ; pp. 507–513. ?Alfred Charles Kinsey; Wardell Baxter Pomeroy; Clyde Eugene Martin (1948).Sexual Behavior in the Human Male; pp. 190-205. ?Alice Klein (2004). “Love & Sex Guide”; Retrieved 2 May 2010. ?Ann Byers (2007). “How Do Boys’ Bodies Change during Puberty? “; Frequently Asked Questions about Puberty; pp. 16–25 ? Apter, D (1980). “Serum steroids an