Ovaries secrete steroid hormones which regulate female reproductive organs. Estrogens and progesterone are two important ovarian hormones.
Estrogens are secreted by the theca interna of ovarian follicles. Besides, corpus luteum also secrets some estrogens. There are two important naturally occurring estrogens, estradiol and estrone.
The secretion of estrogens is stimulated by the follicle stimulating hormone (FSH) of the anterior pituitary. It is typical steroid hormone. It stimulates the growth, maturation and functions of female secondary sex organs like uterus, fallopian tubes and the duct system of mammary glands. It is also develops and maintains external female sex characters like high pitch female voice and the female pattern of body hair distribution.
Progesterone is mainly secreted by corpus luteum in non pregnant woman and in early months of pregnancy. However, in later months of pregnancy, placenta is the source of this hormone.
Progesterone brings about most of the pregnancy changes such as uterine growth, attachment of embryo to uterine wall, formation of placenta, holding foetus on uterine wall, and growth of secretary alveoli in mammary glands.
Estrogen vs Progesterone