And all these cells around the follicle are the FECA cells and the granulosa cells. And we'll discuss their function in just a moment. So as our LH de luthanizing hormone and FSH, follicle stimulating hormone, increases in concentration, they affect the, theca cells and the granulosa cells found in the follicle. So our LH stimulates the Thicka cells to produce androgens and the androgens are taken up by the other cells called the granulosis cells, also found the follicle and the granulosis cells, they use the androgens to produce estrogen. And that's exactly why, if we look at the diagram, when the follicle begins to develop, the estrogen concentration shown in green begins to increase in concentration. So we have an increase as shown here.