What action does estrogen promote during the menstrual cycle?

Estrogen plays a crucial role in preparing the uterus for potential pregnancy during the menstrual cycle, which involves promoting mucosal changes. Specifically, estrogen is responsible for stimulating the growth and development of the endometrium, the mucosal lining of the uterus. As estrogen levels rise during the follicular phase of the cycle, this hormone encourages the thickening of the endometrial lining, making it more receptive to a fertilized egg.

This preparation is vital because if fertilization occurs, the thicker endometrial lining provides an optimal environment for implantation. If no fertilization happens, hormone levels will drop, leading to menstruation. While estrogen is involved in ovulation and can indirectly influence fertilization through its overall role in the reproductive cycle, the most direct action attributed to estrogen during this phase is the promotion of mucosal changes in the uterus.