Now, as time progresses and as our lady cells continually release our testosterone into our blood, that increases the level of testosterone in our blood. And as the blood testosterone level increases, the testosterone can actually go and inhibit the hypothalamus from releasing the gonadotropin releasing hormone and it can also inhibit the anterior pituitary gland from releasing our luteinizing hormone as well as the follicle stimulating hormone. And this type of pathway is known as negative feedback inhibition or negative feedback mechanism. Now, what about our follicle stimulating hormone and what about the surtoli cells? Well, the surtoli cells are these cells shown here. Now, once the follicle stimulating hormone is released into our bloodstream, it travels to the capillaries of this region and it causes these surtoli cells to basically provide the nutrients needed to our sperm cells for them to actually develop into mature sperm cells.