Final answer:
Estrogen performs important functions in the female reproductive system, including stimulating cervical mucus production, thickening the uterine lining, and inducing secondary sexual characteristics.
Step-by-step explanation:
Estrogen, primarily produced by the ovaries, is responsible for several crucial functions in the female reproductive system. It stimulates the cervix to produce a mucus that facilitates the movement of sperm, causes the thickening of the uterine lining in preparation for implantation, and triggers the development of secondary sexual characteristics during puberty.