QS Study

Definition: Puberty means the onset of adult sexual life. It is the time in life when a boy or girl becomes sexually mature. It may be defined as the period when the endocrine and gametogenic functions of the gonads have first developed to the point where reproduction is possible. It causes physical changes and affects boys and girls differently.

Time of onset:

  • Boys: 9-14 years
  • Girls: 8-13 years.


1st: Thelarche: Development of breast

2nd: Puberche: Development of axillary and pubic hair.

3rd: Menarche: Onset of the first menstrual period.

4th: Adrenarche: Onset of increasing secretion of adrenal androgens. Strenarche occurs at age 8 -10 years in the girl and 10-12 years in the boy.

Fig: The age of development of features of puberty.

In girls:

  • The first sign of puberty is usually breast development.
  • Then hair grows in the pubic area and armpits.
  • Menstruation (or a period) usually happens last.

In boys:

  • Puberty usually begins with the testicles and penis getting bigger.
  • Then hair grows in the pubic area and armpits.
  • Muscles grow, the voice deepens, and facial hair develops as puberty continues.

Control of the onset of puberty: At puberty –

  1. The hypothalamus releases GnRH,
  2. Stimulates at the anterior pituitary gland,
  3. Secretion of gonadotropin,
  4. Stimulating Hormone.
  5. Stimulation of gonads
  6. The release of sex hormones
  7. Puberty appears.

But before puberty, gonadotropins are not secreted. Because during the period from birth to puberty, a neural mechanism is operating to present the normal releasing of GnRH. The onset of normal GnRH initiated by some maturation process that occurs elsewhere in the brain, perhaps somewhere in the limbic system.