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Puberty In Females and Males | Get Facts and Info About Puberty

Puberty In Females and Males- Facts and Info About Puberty

PUBERTY

Puberty In Females and Males Get Facts and Info About Puberty

Period when the endocrine and gametogenic functions of the gonads have first developed to the point where reproduction is possible

This is characterized by sequence of events by which a child becomes a young adult;

  • The beginning of gametogenesis
  • Secretion of gonadal hormones
  • Development of secondary sexual characters and reproductive functions
  • Sexual dimorphism is accentuated.

 

Factors affecting the onset of puberty

The age of onset of puberty varies and is more closely correlated with osseous maturation than with chronological age

  • Genetic/Ethnic factors
  • Environmental/Geographical factors

 

Prepubertal stage (8–9 yr of age)

The hypothalamic-anterior pituitary-gonadal axis is suppressed by;

  • Neuronal restraint pathways
  • Negative feedback provided by minute amounts of circulating gonadal steroids

Thus there are undetectable serum levels of;

  • luteinizing hormone (LH)
  • sex hormones (i.e., estradiol in girls, testosterone in boys)

Evidence of hypothalamic-anterior pituitary-gonadal interaction during the prepubertal period resides in the fact that serum follicle-stimulating hormone (FSH) concentrations are detectable in most children and may be increased (with serum LH concentrations) in;

  • Turner syndrome
  • Anorchia

 

Peripubertal period (1-3 yr before the onset of puberty)

Pulsatile secretion of low levels of LH during sleep secondary to endogenous episodic discharge of hypothalamic gonadotropin-releasing hormone (GnRH). Nocturnal pulses of LH continue to increase in amplitude and, to a lesser extent, in frequency as clinical puberty approaches. Serum LH concentrations rise earlier in the course of the pubertal process in boys than in girls.

This pulsatile secretion of gonadotropins is responsible for;

  • Enlargement and maturation of the gonads
  • The secretion of sex hormones
  • Appearance of the secondary sex characteristics

GnRH is the major, if not the only, hormone responsible for the onset and progression of puberty.

A second critical event occurs in middle or late adolescence in girls, in whom cyclicity and ovulation occur. A positive-feedback mechanism develops whereby rising levels of estrogen in midcycle cause a distinct increase of LH.

 

Puberty in Girls (8-13yr)

  • Thelarche (Development of Breasts) – Breast bud – 10–11 yrs
  • Pubarche (Development of axillary and pubic hair) -Appearance of pubic hair – 6–12 mo later
  • Peak height velocity occurs early (at breast stage II–III, typically between 11 and 12 yr of age) in girls and always precedes menarche.
  • Menarche (first menstrual period) Interval to menarche – 2–2.5 yr but may be as long as 6 yr after thelarche. Mean age of menarche – 12.75 yr. (13.5 yrs in rural girls)

 

Puberty in Boys (9-14yr)

  • Growth of the testes (>3 mL in volume or 2.5 cm in longest diameter)
  • Thinning of the scrotum
  • Pigmentation of the scrotum
  • Growth of the penis, seminal vesicles and prostrate
  • Pubic hair then appears
  • Appearance of axillary hair usually occurs in midpuberty, 2 yr after pubic hair.
  • In boys, unlike girls, acceleration of growth (5-15cm/yr in early adolescence but later drops) begins after puberty is well under way and is maximal at genital stage IV–V (typically between 13 and 14 yr of age).
  • In boys, the growth spurt occurs approximately 2 yr later than in girls, and growth may continue beyond 18 yr of age.

 

Adrenarche

Adrenal cortical androgens also play a role in pubertal maturation.

Serum levels of dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) begin to rise at approximately 6–8 yr of age, before any increase in LH or sex hormones and before the earliest physical changes of puberty are apparent.

DHEAS is the most abundant adrenal C-19 steroid in the blood, and its serum concentration remains fairly stable over 24 hr; a single measurement of this hormone is commonly used as a marker of adrenal androgen secretion.

Although adrenarche typically antedates the onset of gonadal activity (i.e., gonadarche) by a few years, the two processes do not seem to be causally related, because adrenarche and gonadarche are dissociated in conditions such as;

  • Central precocious puberty
  • Adrenocortical failure

ADOLESCENCE

The period of life beginning with puberty and ending with completed growth and physical maturity.

Between the ages of 10 – 19 yr (WHO), children undergo rapid changes in;

  • Phenotypic changes – Body size and shape
  • Neuroendocrine changes – Hormones set the developmental agenda in conjunction with social structures designed to foster the transition from childhood to adulthood.
  • Physiology
  • Psychological functioning
  • Social functioning

 

10-24 yr – Young Adults

 

Marshall – Tanner Classification of Sex Maturity Stages in Girls                   

SMR Stage Pubic Hair Breasts
1

2

 

 

3

 

4

 

5

Preadolescent

Sparse, lightly pigmented, straight, medial border of labia

Darker, beginning to curl, increased amount

Coarse, curly, abundant but amount less than in adult

Adult feminine triangle, spread to medial surface of thighs

Preadolescent

Breast and papilla elevated as small mound; areolar diameter increased

Breast and areola enlarged, no contour separation

Areola and papilla form secondary mound

 

Mature; nipple projects, areola part of general breast contour

SMR = sexual maturity rating.

 

Marshall – Tanner Classification of Sex Maturity Stages in Boys                                     

SMR Stage Pubic Hair Penis Testes
1

2

 

 

3

 

4

 

 

 

5

None

Scanty, long, slightly pigmented

 

Darker, starts to curl, small amount

Resembles adult type, but less in quantity; coarse, curly

Adult distribution, spread to medial surface of thighs

Preadolescent

Slight enlargement

 

 

Longer

 

Larger; glans and breadth increase in size

 

Adult size

Preadolescent

Enlarged scrotum, pink texture altered

Larger

 

Larger, scrotum dark

 

 

Adult size

SMR = sexual maturity rating.

 

Developmental lines occur within three periods of adolescence;

 

Central Issues in Early, Middle, and Late Adolescence                                    

Variable Early Adolescence Middle Adolescence Late Adolescence
Age (yr) 10–13 14–16 17–20 and beyond
SMR*         1–2 3–5 5
Somatic Secondary sex characteristics; beginning of rapid growth; awkward Height growth peaks; body shape and composition change; acne and odor; menarche; spermarche Slower growth
Sexual       Sexual interest usually exceeds sexual activity Sexual drive surges; experimentation; questions of sexual orientation Consolidation of sexual identity
Cognitive and moral Concrete operations; conventional morality Emergence of abstract thought; questioning mores; self–centered Idealism; absolutism
Self–concept Preoccupation with changing body; self–conscious Concern with attractiveness, increasing introspection Relatively stable body image
Family Bids for increased independence; ambivalence Continued struggle for acceptance of greater autonomy Practical independence; family remains secure base
Peers Same–sex groups; conformity; cliques Dating; peer groups less important Intimacy; possibly commitment
Relationship to society Middle–school adjustment Gauging skills and opportunities Career decisions (e.g., dropout, college, work)

SMR = sexual maturity rating.

 

 

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