What is the source of estrogen after menstruation ends?

After menstruation ends, the primary source of estrogen is the developing ovarian follicles. As these follicles mature, they produce estrogen, specifically estradiol, which helps regulate the menstrual cycle and prepare the uterine lining for potential implantation of a fertilized egg. Additionally, the adrenal glands also contribute a small amount of estrogen throughout the menstrual cycle.