means increased activity of the suprarenal cortex at puberty with increased production of adrenal androgens which lead to appearance of pubic and axillary hair.
Cause of puberty:
During childhood , the hypothalamus is extremely sensitive to the negative feedback exerted by the small quantities of estradiol & testosterone produced by the child's ovaries .
As puberty approaches , the sensitivity of the hypothalamus is decreased and subsequently , it increase the pulsatile GnRH secretion .
The anterior pituitary responds by progressive secretion of FSH and LH associated with increased secretion of growth hormone .
The ovaries respond to the increase Gonadotrophin secretion by follicular development & estrogen secretion .
Estrogen causes development of the genital organs and the appearance of the secondary sexual characters .
With increased estrogen secretion , menarche and cyclic estrogen secretion occurs .
Factors affecting the initiation of pubertal development :
1 - Height and weight ratio (nutritional factors).
2 - Maturation of the hypothalamus .
3 - Increased neurotransmitter output in CNS .
4 - Onset of adrenal androgen activity
FEMALE PRECOCIOUS PUBERTY
It means menarche or appearance of any of the secondary sexual characters before the age of 8 years.
1 - True precocious puberty
It is due to increased production of pituitary gonadotrophins.
2 - False(pseudo-precocious puberty)
It is of peripheral origin.
It is due to secretion of sex hormones; (estrogen or androgen) which is not dependent on pituitary gonadotrophins as in case of estrogenic or androgenic ovarian tumors.
3 - Incomplete precocious puberty .
In this case only one pubertal change as breast development is present before the age of 8 years without the presence of any other pubertal changes and in absence of increased estrogen production.
The other pubertal changes occur at the normal age.