As the levels of FSH lower, the dominant follicle continues to mature and release estrogen. The other follicles who did not win the race die off. Now, it's only about the winning egg or eggs (in the case of un-identical twins).
The estrogen released by the mature follicle does more than just shut off the supply of FSH from the pituitary. The estrogen is also responsible for stimulating the endometrium, or lining of the uterus, to grow. The endometrium grows from about 0.5 millimeters in thickness at the beginning of your cycle, to 5.5 millimeters in thickness by the end.
The estrogen hormones are also responsible for the increase in fertile cervical mucus and changes in your cervical position, preparing conditions that will be just right for transport and acceptance of sperm to the egg. It also increases your level of sexual desire, biology's way of helping you time sex for pregnancy.
