[Endocrine maturation].

The beginning of puberty is caused by a decrease in high gonadostate sensibility to prepubertal levels of sexual steroids. What produces this change and timing is still unknown. However, it seems that the adrenal (delta-4 Androstenedione) as well as the pineal may play an important role. When it comes to that point, the hypothalamic LH-RH provokes a strong LH, FSH secretion; this triggers the gonadal sex-steroids production, which induces in turn the appearance of the secondary sex characteristics. Two years after the so called "mid growth spurt" begins the pubertal growth acceleration which reaches its peak to 2, 4 yrs later. The pubertal development is regulated by genetic factors. Bone age should be referred as a much better indicator than the chronological age.