What are the changes that occur in a girl during adolescence?

In girls, several hormonal changes occur during adolescence. The release of hormones causes several changes in physical appearance. The brain releases GnRH (Gonadotropin-releasing hormone) that stimulates the pituitary to release LH (Luteinizing hormone) and FSH (Follicle stimulating hormone). These hormones cause the maturation of the ovarian follicles and the release of eggs from the ovary leading to the beginning of the menstrual cycle. The release of these hormones also leads to the development of some secondary sexual characters such as:

• Development of breasts.
  
• Development of hair in armpits and pubis.
  
• Widening of pelvis and deposition of fats in hips, thigh and upper arms.
  
• Secretion of oil (sebum) from skin.