Well, it turns out that the FECA cells are stimulated by a hormone produced in our body known as the luteinizing hormone LH. And what the luteinizing hormone does is it stimulates the FECA cells to basically transform cholesterol into androgens. And then these androgens are released into the grainylosis cells and the follicle stimulating hormone also produced inside our body stimulates these granolosis cells, the green cells to transform androgen by using a special type of enzyme into a type of sex steroid hormone known as estrogen. And we have different types of estrogen. Now, what exactly is a function, what's the purpose of estrogen? Well, what estrogen basically does is it thickens, it increases the layer of the wall of the uterus, it increases the size of the endometrium and it prepares the endometrium for implantation by the zygote if fertilization actually takes place.