Estrogens are mainly produced by the ovaries and affect various tissues, including the breast, bones, and cardiovascular system. They promote the growth of the endometrial lining during the first half of the menstrual cycle. Progestins, on the other hand, are produced in the second half of the menstrual cycle by the corpus luteum in the ovary. They help stabilize the endometrial lining, making it suitable for implantation of a fertilized egg and support early pregnancy.
