Question

Human chorionic gonadotropin is secreted by
(A) Chorion
(B) Amnion
(C) Corpus luteum
(D) Placenta

Answer 1

Hint: Human chorionic gonadotropin (hCG) is a hormone specifically synthesized during pregnancy. In fact, hCG test is performed in order to measure relative amount of this hormone in blood or urine, to confirm pregnancy.

Complete answer:
After the fertilization of ovum with sperm, diploid zygote is formed. Fertilization takes place in fallopian tubes. Zygote gets developed into an embryo, which travels to the uterus where it gets implanted. Moreover, there are few extra embryonic membranes which protect the growing embryo. They are as follows - amnion, chorion, allantois and yolk sac. Amnion being the innermost membrane of the embryo, creates a fluid-filled cavity which possesses amniotic fluid. Amniotic fluid is useful in protecting the embryo from mechanical stress. Yolk sac and allantois in human embryos don't perform much function as in birds and reptiles.
After implantation, finger-like projections emerge from chorion, known as chorionic villi. It is usually surrounded by tissue of the uterus and supplied with maternal blood. Chorionic villi and the uterine tissue get integrated together as a single structure which connects the mother’s body with the foetus, known as placenta.
Placenta is considered as a temporary endocrine tissue as it is formed only during pregnancy and secretes hormones.
The hormones secreted by placenta are human chorionic gonadotropin (hCG), oestrogen, progesterone and human placental lactogen (hPL).

Hence the correct answer is option(D)

Note: hCG is also synthesized in women who are not pregnant. This condition represents tumours in the ovary and uterus, where the cancerous cells produce hCG.