Such changes are caused by processes within the brain, and in particular by a neuroendocrine gland, the pituitary gland, which secretes two hormones, FSH and LH.

• 这种改变是由大脑内的程序引起，特别是具有神经内分泌功能的垂体前叶和脑垂体，他们分泌两种激素：促卵泡激素和促黄体激素。