ANATOMY

Detailed explanation-1: -The hormone responsible for these changes is progesterone, which is manufactured by the corpus luteum. Under the influence of progesterone, the uterus begins to create a highly vascularized bed for a fertilized egg. If a pregnancy occurs, the corpus luteum produces progesterone until about 10 weeks gestation.

Detailed explanation-2: -At the start of each menstrual cycle, levels of the hormone estrogen begin to rise, which causes the uterine lining to grow and thicken. When the ovary releases an egg, levels of another hormone, progesterone, increase.

Detailed explanation-3: -In response to this release of GnRH, the anterior pituitary will release FSH and LH, which will subsequently act on the gonads. In the female ovary, this release of FSH and LH on the gonads causes the release of progesterone.

Detailed explanation-4: -If the egg is fertilised, progesterone stimulates the growth of blood vessels that supply the lining of the womb (endometrium) and stimulates glands in the endometrium to secrete nutrients that nourish the early embryo.