Every girl experience several changes in their body during the puberty.
Puberty is triggered by the pea-size pituitary gland on the underside of the brain. What prompts it to move into action remains a mystery. But results are instantly apparent when it begins producing tiny amounts of gonadotropic hormone-which stimulates ovaries in girls, testes in boys. During childhood theseglands have remained latest until stimulus they begin producing hormones of their own.
In the adolescent girl newly activated ovaries produce estradiol in fantastically small amounts-a daily out put equal to 1/1000 of a grain of sugar! But that is enough of this potent stuff to propel the girl-child into womanhood. She begins shooting up at a rate of as much as two inches a year, leaving laggard boys behind. In fact that further contributes to the antipathy between between the sexes at this age. (Propelling a girl half a head taller around a dance floor represents exquisite torture for both partners.)
Pelvic bones begin to grow, widening hips and providing a bony cradle for babies-to-be. Breast tissue proliferates-slowly at first, but ever faster under the hormone influence. Tissue in the birth canal thickens and toughens to be ready to withstand the rigors of childbirth. The womb, too, enlarges from the plum size of childhood to the pear size of adulthood.
It takes perhaps two years to transform the female body in preparation for potential motherhood. Now important events begin in the ovaries themselves. These glands contain at birth the lifetime supply of undeveloped egg cells, estimated at 420,000- an astonishing number, since only 400 to 500 will be expelled during a woman’s fruitful years.