THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -If a fertilised egg implants in the lining of the uterus, the corpus luteum continues to produce progesterone, which maintains the thickened lining of the uterus. If pregnancy does not occur, the corpus luteum dies, progesterone levels drop, the uterus lining sheds and the period begins again.

Detailed explanation-2: -If fertilization does not occur, the endometrium, coupled with blood and mucus from the vagina and cervix (the lower, narrow part of the uterus located between the bladder and the rectum) make up the menstrual flow (also called menses) that leaves the body through the vagina.

Detailed explanation-3: -The progesterone prepares the body for pregnancy in the event that the released egg is fertilised. If the egg is not fertilised, the corpus luteum breaks down, the production of progesterone falls and a new menstrual cycle begins.

Detailed explanation-4: -The luteal phase begins after you ovulate. The dominant follicle that releases an egg at ovulation changes into a structure called the corpus luteum. The corpus luteum produces progesterone, along with some estrogen. Progesterone levels increase in the luteal phase, which help thicken the lining of your uterus.