Puberty

ผศ. ดร. พรภมิล ตัง้ชยัสนิภาควชิาสรรีวทิยา คณะแพทยศาสตร์มหาวทิยาลยัเชยีงใหม่E-mail: ptangcha@gmail.comโทร : 053-945362-4 ext 120

BMES 309 Reproductive system

Define the terms: Puberty, Adolescence, Pubarche

Adrenarche, Gonadarche, Thelache and Menarche

Describe the physical changes that take place

during puberty in boy and girl

Describe the stages of sexual maturation during

puberty in boy and girl

Describe the timing of onset puberty, mean Age of

menarche and secular trends

Identify factors associated with timing of puberty

Describe the hormonal changes influencing the

onset of puberty

Identify the classifications of abnormal puberty onset

Learning Objectives

Definition

Adolescence: a complex and dynamic process of

development:

– physical development (puberty) – cognitive and psychological development

– social development.

A transitional period of development from the onset

of puberty to maturity.

Adolescence is roughly considered to be the period

between 13 and 19 years of age.

Puberty or pubescence:

The general term for biological maturation

into sexual maturity.

Definition

• Boys and Girls mature at different rates• Girls usually begin puberty before boys.

Pubarche

– First appearance of pubic hair

Adrenarche

– Maturing of the adrenal glands

– Production or androgens (DHEA)

– Between ages 6 and 9

Gonadarche

– Maturing of the sex organs

– Girls: ovaries increase estrogen

– Boys: testes increase androgens

Definition

Thelache "breast bud".

– The first stage of secondary (postnatal) breast

development, usually occurring at the beginning of

puberty in girls.

– May occur on one side first, or both sides

simultaneously.

– The first physical change of puberty in girls, and is

a result of rising levels of estradiol.

Menarche– The onset first menstrual bleeding.

– First menstrual cycles are usually irregular and

without ovulation (anovulatory cycle).

Definition

Definition

Spermarche

first ejaculation typically occurs by age 15

initial period of sterility

Secondary sex characteristics

a physical characteristics that appears in

members of one sex at puberty and is not

directly concerned with reproduction

also called secondary sexual characteristics

– Prepubertal Phase: the time before age 9 in boys

and before 8 in girls.

– Pubertal phase: This period contains the most

nocticable growth spurt and physical changes.

– Postpubertal phase (adolescence): Last for a

year and a half in girls and is somewhat shorter in

the case of boys.

Phases of pubertal development

During puberty we can grow in many areas.

Normal pubertal development

Boys Girls

Age of start (yrs) 11.5 (9-14) 10.5 (8-13)

First sign of

puberty

testicular volume

>4 ml breast budding

Growth velocity

(cm/yr)

10.3 (Tanner III-

IV)

9.0 (Tanner II-III)

Duration of

puberty (yrs)

3.2 ± 1.8

(adult size of

testis)

2.4 ± 1.1

(menarche)

Problems with The Definition of Puberty

In girls

– Breast development maybe difficult to assess

using visual inspection

– Discerning breast from fat tissue is a key concern

in overweight girls

– Key- palpate under the aerolar

In boys

– First sign of puberty is not noticed

– Need to compare testicular volume with

orchidometer

The Sexual Maturity Rating (SMR)

W. Marshall and J. M. Tanner (1969).

Determine whether development is normal for a given age.

These ratings are often referred to as

Tanner Stages 1 to 5.– Growth spurt

– The development of secondary sexual characteristics• Breast development

• Pubic hair growth

• Penis and scrotum

Tanner Stages

Girls: breast (B1-5), pubic hair (Pu1-5),

axillary hair (A1-5), menarche

Boys: testicular volume > 4 ml, penis

enlargement (G1-5), pubic hair (Pu1-5),

axillary hair (A1-5), spermarche

SMR Breasts

Stage 1 Preadolescent; elevation of papilla only

Stage 2Breast and papilla elevated as small mound;

areola diameter increased

Stage 3Breast and areola enlarged with no

separation of their contours

Stage 4

Projection of areola and papilla to form

secondary mound above the level of the

breast

Stage 5Mature; projection of papilla only, areola has

recessed to the general contour of the breast

Tanner staging of Breast development

Breast development in girl

B1 B2 B3

B4 B5

Breast development in girl

The first physical sign of puberty in girls is

Thelarche (the appearance of breast buds).

Stage II to Stage III = 1.3 yrs avg.

Stage III to Stage V = 2.4 yrs avg.

The characteristics of the stages are similar in all

female.

Ovarian estrogen chiefly stimulates breast

development.

Adult breast sizes and shapes are vary. Big or

small, they are all normal : genetics and nutritional

factors

SMR Pubic Hair

Stage 1Preadolescent, no pubic hair except for a

fine "peach fuzz" body hair

Stage 2Sparse, slightly pigmented, straight, at

medial border of labia

Stage 3Darker, beginning to curl, increased

amount

Stage 4Coarse, curly, abundant, but amount less

than in adult

Stage 5Adult feminine triangle, spread to medial

surface of thighs

Tanner staging of pubic hair growth in girl

Pubic hair growth

P1 P2 P3

P4 P5

The sequence of pubertal events in girls

1st sign = breast budding ~10.9 yrs

Pubarche ~11.2 yrs.

PHV~ 12.2 yrs

Menarche~12.7 yrs

PHV=peak height velocity

Other physical changes

Increase in size of uterus and ovaries

– Whitish vaginal secretions (physiologic

leukorIrhea)

Pelvic shape, fat distribution, and body

composition

– the typical female fat distribution of breasts,

hips, buttocks and thighs.

– This produces the typical female body shape

Body odor, skin changes, and acne

Penis and scrotum growth

SMR Genitals

Penis Testes

Stage 1 Prepubertal Prepubertal

Stage 2 Slight or no enlargement Beginning enlargement of

testes and scrotum; scrotal

skin reddened, texture altered

Stage 3 Longer Further enlargement of testes

and scrotum

Stage 4 Larger in breadth, glans

penis develops

Testes and scrotum nearly

adult size

Stage 5 Mature adult size Adult

Genitalia & pubic hair growth

<12 CM3 may infertile

Orchidometer

SMR Pubic Hair Other changes

Stage 1 Prepubertal stage -

Stage 2 Scanty, long, slightly

pigmented, primarily at base

of penis

-

Stage 3 Darker, coarser, starts to

curl, small amount

Gynecomastia may occur,

Voice breaks,

Muscle mass increases

Stage 4 Coarse, curly; resembles

adult type but covers

smaller area

Axillary hair, Voice changes,

Acne Vulgaris

Stage 5 Adult quantity and

distribution, spread to

medial surface of thighs

Secondary sexual characteristics :

Facial hair present on sides

Mature male physique (Male

musculature and body shape)

Body odor, skin changes, acne

Gynecomastia disappears

The sequence of pubertal events in boys

1st sign of puberty

(11.5 yrs.)

Enlarged testes

Height spurt~ 14 yrs

Spermarche~ 13.5 yrs

1st ejaculation 13 yrs

Pubertal growth spurt

In the male, the pubertal growth spurt is a late event starting

about two years later than in females.

Sexual Maturation

The changes in sexual maturation that occur for males and females during early adulthood.

Misconception

There is a common misconception that the

difference between the onset of puberty in

males and females is 2 years.

This applies only to the growth spurt and not

to pubertal (SMR) changes.

The onset of pubertal changes are only about

6 months later than in females.

Brain development

The neuroendocrine regulation of puberty

involves two major components:

– The timing

– The control of sexual maturation

Regulation of pubertal development

Hypotheses on the mechanism

of the onset of puberty

Gonadostat

Hypothalamic neurons

release protein called “kisspeptin”

Kisspeptin bind with

GPR54 receptor

Release of GnRH

Release of FSH&LH

from anterior pituitaryFSH&LH stimulates gonads

Sex steroids production to

promotes secondary

sex characteristics

Sex steroids also

shut down

GnRH production

Hormone changes in puberty

HYPOTHALAMUS

PITUITARY

SOMATIC

GROWTH

SEXUALMATURATION

LIVER

OVARY

GnRH AND GHRH

GROWTH

HORMONELH & FSH

INSULIN

SEX STEROID SYNTHESIS SHBG IGFBP-1 IGF-1

Hormone changes in puberty in girls

increase in the frequency

and amplitude of the

GnRH pulse generator

increase in amplitude and

frequency of LH pulse

These increases are first

detected as nocturnal Gn

pulses

Factor That Affect Puberty

Genetics

Race/Ethnicity

Previous nutrition

Subcutaneous fat

Birth weight

Abnormal puberty onset

Precocious puberty

Delayed puberty

Precocious Puberty

Definition

Precocious onset of puberty is defined as

occurring younger than 2 SD before the

average age

Cut points

age of 8 year in girls or

age of 9 year in boys.

Gonadotrophin-dependent / True or Central

precocious puberty

– idiopathic, familial, CNS lesions, e.g. postirradiation,

surgery, tumours, hydrocephalus

Gonadotrophin-independent / precocious

pseudopuberty

– McCune-Albright syndrome ,(polyostotic fibrous

dysplasia of bone, café-au-lait spots, Excessive

estrogen in girls or excess testorsterone in boys is

seen together with no LH or FSH response to LHRH)

– Congenital adrenal hyperplasia (CAH)

– Sex steroid secreting tumours: adrenal or ovarian

Causes of precocious puberty

Delayed puberty

Puberty is delayed when more than 2

standard deviation (SD) from the mean

age of pubertal onset For boys: For girls:

- genital stage 1 after 14

years

- >5 years from initiation to

completion of genital

enlargement

- lack of breast development

after 13 years (no glandular

tissue),

- lack of pubic hair > 14

years

- primary amenorrhae at

15.5-16y

- >5 years from initiation of

breast growth to menarche

Gonadal failure (Hypergonadotrophic hypogonadism)

– Turner’s Syndrome

– Post-malignancy chemo / radiotherapy / surgery

– Polyglandular autoimmune syndromes

Gonadal deficiency

– Congenital hypogonadotrophic hypogonadism (+anosmia)

– Hypothalamic/pituitary lesions (tumours, post-radiotherapy)

– Rare gene mutations inactivating FSH/LH or their receptors

Causes of delayed puberty

THE END