In addition, ovulation is the primary way that females create the hormone progesterone. When an ovum is released from the ovary, the structure that remains develops into the corpus luteum. The corpus luteum emits the hormone progesterone during the 10–16 days of the luteal phase. Without experiencing regular, ovulatory menstrual cycles, the female is not secreting the hormone progesterone during the luteal phase of her cycle. Progesterone directly stimulates osteoblasts to make new bone. Therefore if the woman is not ovulating, she is not creating progesterone, and misses out on this opportunity to stimulate new bone growth.