During puberty, the monthly menstrual and ovarian cycles begin, which is when the endometrium, or inner lining of the uterus, goes through cyclic changes in response to the ovarian hormones.

在青春期，月经和卵巢周期开始出现，此时子宫内膜（或子宫内衬）对卵巢激素作出反应，发生周期性变化。