Menstrual Cycle

• • Day 1 to 5:
  • In the ovary, FSH secreted by the Pituitary Gland to stimulate the maturation of ONE follicle in the ovary.
  • In the uterus: the endometrium breaks down; menstruation

  
• • Day 5 to 12:
  • In the ovary the follicle keeps maturing
  • In the uterus, oestrogen is secreted by follicle and the ovarian tissues to prepare the endometrium

  
• • Day 13/14/15:
  • In the ovary, LH is also secreted by the Pituitary Gland to trigger the release of the egg from follicle into the fallopian tube

  
• • Day 15 to 28:
  • In the ovary, LH triggers formation of Corpus Luteum
  • In the uterus: progesterone is secreted by Corpus Luteum to keep endometrium thick, waiting for possible embryo implant.

  
• • Day 28 – Scenario 1: Egg not fertilized
  • No implantation takes place, the Corpus Luteum degenerates, causing a lack of progesterone.
  • This means that endometrium is no longer thick, back to Day 1

  
• • Day 28 – Scenario 2: Egg is fertilized
  • Implantation occurs.
  • This makes the hormones to keep the Corpus Luteum maintained which means that progesterone is high.
  • This keeps the Endometrium thick for pregnancy