menstrual cycle

• The Menstrual Cycle

  1. Stage 1: Menstruation starts, lining of uterus breaks down and is released

  2. Stage 2: Uterus lining repaired, becomes thick spongy layer full of blood vessels

  3. Stage 3: Egg develops and is released from ovary (ovulation) at about day 14

  4. Stage 4: Lining maintained for about 14 days, if no fertilised egg implants then lining breaks down and cycle starts over
• Hormones controlling the Menstrual Cycle

  • FSH (follicle-stimulating hormone)
  • Oestrogen
  • LH (luteinising hormone)
  • Progesterone
• FSH (follicle-stimulating hormone)


  1. Released by pituitary gland
  2. Causes a follicle (egg and surrounding cells) to mature in one of the ovaries
  3. Stimulates oestrogen production
• Oestrogen


  1. Released by the ovaries
  2. Causes lining of uterus to thicken and grow
  3. High level stimulates LH surge
• LH (luteinising hormone)


  1. Released by pituitary gland
  2. LH surge stimulates ovulation, follicle ruptures and egg is released
  3. Stimulates remains of follicle to develop into corpus luteum which secretes progesterone
• Progesterone


  1. Released by corpus luteum after ovulation
  2. Maintains lining of uterus
  3. Inhibits release of FSH and LH
  4. When progesterone level falls and oestrogen is low, uterus lining breaks down
  5. Low progesterone allows FSH to increase, restarting cycle
• If fertilised egg implants in uterus (woman becomes pregnant)

  Progesterone level stays high to maintain uterus lining during pregnancy