Question

During bleeding phase of menstrual cycle unfertilised secondary oocyte undergoes autolysis. The interplay of hormones then is

• A. progesterone and estrogen continue the hypertrophy of endometrial lining
• B. prolactin and progesterone reduces $LH$ level causing regression of corpus luteum
• C. progesterone inhibits the release of $LH$ from pituitary causing regression of corpus luteum
• D. prolactin and estrogen inhibits progesterone secretion leading to sloughing off uterine lining

Answer 1

Answer: (C)

If fertilisation does not occur, the secondary oocyte undergoes autolysis and progesterone (secreted by persistent corpus luteum) inhibits the release of $LH$ from pituitary. Reduction of $LH$ level causes regression of corpus luteum by autolysis and thus fall in the progesterone level in the blood. Due to deficiency of progesterone, uterine lining sloughs off causing bleeding. This whole phase is called bleeding phase.