Q. Which of the following placental hormones stimulates and maintains the corpus luteum to secrete its hormones?
Solution:
Interdigitation of the chorionic villi and uterine tissue with each other leads to the formation of a structural and functional unit called the placenta between the developing embryo (foetus) and maternal body.
Other than providing nutrition to the embryo, the placenta also acts as an endocrine tissue and produces several hormones, like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens, etc. Close to the time of parturition, a hormone called relaxin is also secreted by the ovary. Out of these hormones, hCG, hPL and relaxin are produced in women only during pregnancy.
Initially, the human chorionic gonadotropin (hCG) is released by the syncytiotrophoblast which develops from the trophoblast. This eventually forms the placenta.
hCG stimulates the corpus luteum to secrete progesterone. Implantation occurs after 5-6 days of ovulation and hCG is produced by the 10th day. Progesterone is required for maintaining uterine thickness in order to support pregnancy. Once the placenta is developed, hCG levels decrease as the placenta takes over the function of the corpus luteum. However, hCG can still be detected till the later stages of pregnancy, especially in higher levels during labour.
Estrogen is a female sex hormone and is produced by the granulosa cells of the ovary. It plays a role in maintaining pregnancy and preventing miscarriage and is responsible for the onset of various hormonal processes required for the development of the foetus.
Chorionic corticotropin helps in the release of adrenocorticotropic hormone which stimulates the synthesis of cortisol, glucocorticoids, etc.
Chorionic thyrotropin is known to function as thyroid-stimulating hormone.
Other than providing nutrition to the embryo, the placenta also acts as an endocrine tissue and produces several hormones, like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens, etc. Close to the time of parturition, a hormone called relaxin is also secreted by the ovary. Out of these hormones, hCG, hPL and relaxin are produced in women only during pregnancy.
hCG stimulates the corpus luteum to secrete progesterone. Implantation occurs after 5-6 days of ovulation and hCG is produced by the 10th day. Progesterone is required for maintaining uterine thickness in order to support pregnancy. Once the placenta is developed, hCG levels decrease as the placenta takes over the function of the corpus luteum. However, hCG can still be detected till the later stages of pregnancy, especially in higher levels during labour.
Chorionic corticotropin helps in the release of adrenocorticotropic hormone which stimulates the synthesis of cortisol, glucocorticoids, etc.
Chorionic thyrotropin is known to function as thyroid-stimulating hormone.