An extremely rare occurrence in humans is a multiple pregnancy with the embryos at different stages due to fertilization weeks apart.What mechanism normally prevents this from happening?
A)The embryo's secretion of FSH and LH maintains the corpus luteum,keeping estradiol and progesterone high until the placenta takes over secretion of these hormones.
B)The embryo's secretion of GnRH maintains the corpus luteum,keeping FSH and LH high until the placenta takes over secretion of these hormones.
C)The embryo's secretion of hCG maintains the corpus luteum,keeping estradiol and progesterone high until the placenta takes over secretion of these hormones.
D)The follicle's secretion of polar bodies maintains the fimbriae,keeping estradiol and progesterone high until the fallopian tube takes over secretion of these hormones.

Question

Quizplus · Accepted Answer

After fertilization, the embryo produces human chorionic gonadotropin (hCG), which maintains the corpus luteum and keeps the levels of estradiol and progesterone high until the placenta can take over their secretion. This ensures that the endometrium is maintained and that no other follicles are ovulated during pregnancy. Therefore, if fertilization occurred weeks apart, the hCG from the first embryo would have already dissipated, and the corpus luteum would have regressed, making it highly unlikely for subsequent embryos to implant and develop.

An Extremely Rare Occurrence in Humans Is a Multiple Pregnancy