When FSH secretion increases is counted as day one, and the initial day of menstruation. Due to
FSH the Ovum begins to enlarge within the ovary, as well as increasing the follicle cells. The FSH causes these cells to secret oestrogen into the blood. When the oestrogen gets to a certain level the
FSH levels decrease, thus causing the oestrogen levels to drop.
When the FSH declines, the anterior pituitary secretes LH as the ovum matures. The increase of LH causes the follicle