What are the three phases of the menstrual cycle?
There is the follicular phase where the uterus lining thickens due to oestrogn and one follicle in the ovary releases an ovum. After ovulation comes the luteal phase where the corpus luteum (formed by the remains of the follicle) releases progesterone which prepares the womb for implantation. If implantation does not occur the menstrual phase occurs as the corpus luteum dies and results in reduced oestrogen and progesterone which causes the endometrium to shed.