menstrual cycle

• females are born with eggs which start to mature at puberty
• 1. FSH from pituitary gland --> egg to mature and the ovaries produce ...
  2. oestrogen --> uterus lining to thicken inhibiting FSH so no more eggs mature until next cycle
  3. this causes pituitary gland to secrete LH --> eggs to be released starts to travel down the uterus
  4. progesterone secreted by the ovaries maintaining the uterus lining