This stimulates the release of other hormones and signals the development of testosterone and sperm in boys and estrogen and egg production in girls. Boys' bodies grow wider and more muscular. The testes enlarge and the penis becomes wider and longer.
Girls start to develop breasts, gain weight on the hips, and develop curvier bodies.
Age at the start of puberty varies considerably. Some children develop early while others are late-bloomers. On average, puberty begins around 8 to 13 in girls and 10 to 15 in boys. In addition to sexual maturation, puberty signals the start of a major growth spurt that lasts about two to three years. Early Onset of Puberty Precocious puberty is the onset of puberty before eight in girls and nine in boys.