The trigger for puberty in both boys and girls is the production of 'gonadotrophin releasing hormone' (GnRH) from a part of the brain called the hypothalamus. This hormone stimulates the pituitary gland to release two hormones, Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH).
I hope this helps. Although there are no options for me to see I believe this would be one.
