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How do estrogen and progesterone influence the menstrual cycle?

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Diagram comparing reproductive pathways: arrows show sexual reproduction forming a diploid zygote from oocyte and sperm, haploid parthenogenesis forming a haploid individual, and two types of diploid parthenogenesis-automixis and apomixis-both resulting in diploid individuals. Symbols indicate haploid and diploid stages. — Animal reproductive system The process of sexual reproduction and several forms of parthenogenesis.

Estrogen and progesterone are essential hormones that regulate the menstrual cycle by orchestrating changes in the ovaries and the uterus to prepare the body for potential pregnancy.12

The Follicular Phase

During the first half of the cycle, maturing ovarian follicles secrete increasing amounts of estradiol, the most potent estrogen. This hormone stimulates the endometrium to thicken and become more vascular, a process known as the proliferative phase. High levels of estrogen also trigger a surge in luteinizing hormone, which induces ovulation.12

The Luteal Phase

Following ovulation, the empty follicle transforms into the corpus luteum, which produces both estrogen and large quantities of progesterone. Progesterone induces the secretory phase, causing the endometrial glands to become tortuous and prepared to receive a fertilized egg.123

Menstruation

If fertilization does not occur, the corpus luteum degenerates, leading to a sharp decline in both hormones. This withdrawal causes the constriction of uterine arteries and the subsequent shedding of the endometrial lining, marking the start of menstruation.12