Which of the following comparisons between menstruation and pregnancy is incorrect?
Menstruation - Corpus Luteum non-ephemeral Pregnancy - Corpus luteum ephemeral
The inner wall of the uterus (endometrium) sheds if there is no implantation of the embryo. The corpus luteum formed by the ruptured graafian follicle after ovulation is a hormone-secreting structure that degenerates to form corpus albicans after a few days unless pregnancy has begun. Therefore, corpus luteum is short lived or ephemeral if fertilisation has not taken place, and non-ephemeral or long lived if pregnancy occurs. Corpus luteum secretes progesterone and estrogen which prepares the uterus for implantation by proliferation of the endometrium. If the egg is not fertilised, estrogen and progesterone levels drop causing the shedding of the endometrial lining which lasts for three to five days. If the egg is fertilised, it possibly results in pregnancy which leads to a hike in HCG levels. The presence of this hormone is checked for confirming pregnancy which lasts for 9 months.