Now, if the corpus luteum decreases its function, that means progesterone concentration will decrease and so will estrogen. And that's because it's the corpus luteum that releases those two hormones. And as we decrease the amount of progesterone and estrogen that means our endometrium will begin to break down, the blood vessels will begin to rupture, releasing blood. And so we'll have the process of menstruation that will initiate and this will discharge the endometrium along with that secondary oxide. And so the thickness of the endometrium will begin to decrease. And at the end of the 28th period, when the estrogen and progesterone concentration drops that entire process, the menstrual cycle will essentially repeat itself once again.