Changes
The testes are a part of the [[endocrine]] system, a network in the body that releases [[hormone]]s into the bloodstream. The hormones released by the testes allows the individual to mature through their physical appearance, thoughts, and behavior.<ref>Grison, Sarah, and Michael S. Gazzaniga. ''Psychology in Your Life''. W.W. Norton & Company, Inc., 2017.</ref>
The testes release sex hormones called [[androgen]]s, while the ovaries produce hormones called [[estrogen]]s, mainly "estradiol." Within the class of androgens, a hormone called "[[testosterone]]" increases about 20 times the level it was before [[puberty]].<ref>Roche & Sun, 2003</ref> Though both males and females have estrogen and androgens, it is the increase of estradiol in girls and testosterone in boys that causes the first physical changes during puberty, which are known as "[[secondary sex characteristicscharacteristic]]s."
==See also==
