This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Placental Hormone Production”.
1. Where do the Placental steroidogenesis takes place in women?
a) Syncytiotrophoblast
b) Morula
c) Infundibulum
d) Uterine wall
View Answer
Explanation: In the syncytiotrophoblast, placental steroidogenesis takes place and the synthesis and secretion of estrogens and progesterone increases during pregnancy in combination with the rise in the mass of the trophoblast. The trophoblast has decreased levels of several enzymes that are essential for estrogen and progesterone de novo development and are dependent on precursors of maternal and fetal origin.
2. Which among the following transcriptions factors is not expressed by the placenta?
a) Tumor Necrosis factor 3
b) Steroidogenic factor 1
c) Maporegenic factor 7
d) Saprogenic factor 9
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Explanation: Steroidogenic factor 1 (SF1), a transcription factor that is an important regulator of genes involved in the production of adrenal and gonadal steroid hormones, is not expressed in the placenta. The protein steroidogenic factor 1 is a transcription factor involved in sex determination by regulating the function of genes associated with the reproductive glands or gonads and adrenal glands.
3. Which among the following enzymes is present in lower concentrations in the placental microsomes?
a) Hydroxymethylguanyl-coenzyme A
b) Hydroxymethylvaleryl-coenzyme A
c) Hydroxymethylglutaryl-coenzyme A
d) Hydroxymethylacetyl-coenzyme A
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Explanation: The amount of an important enzyme required for cholesterol synthesis, hydroxymethylglutaryl-coenzyme A reductase, is low in placental microsomes, even though the trophoblast can synthesise cholesterol from acetate. This is because of the inhibitory effects of elevated cholesterol intracellular concentrations arising from cholesterol esterification inhibition by progesterone.
4. Luteectomy, or removal of the corpus luteum-containing ovary, leads to abortion within the first 35 days after conception.
a) True
b) False
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Explanation: Luteectomy, or removal of the corpus luteum-containing ovary, leads to abortion within the first 35 days after conception, but pregnancy normally continues if these procedures are performed 46 days or more after conception. This suggests that development of placental progesterone is adequate even before the luteal-placental shift to sustain pregnancy.
5. Estrogen action appear to be essential in maintaining pregnancy.
a) True
b) False
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Explanation: Estrogen action does not appear to be necessary in sustaining pregnancy because the sulphate moiety cannot be removed from 16 alpha-hydroxy-DHEAS by a foetus with deletion of the gene encoding placental sulfatase. As a result, maternal estrogen levels reach just around 10% of normal levels.
6. Which cholesterol transporting protein is absent in placenta?
a) Transferrin
b) STAR protein
c) Lipoprotein 1
d) Pyrokine
View Answer
Explanation: The placenta lacks the steroidogenic acute regulatory protein (STAR) that mediates the transfer of cholesterol from the outer membrane to the inner mitochondrial membrane, the location where CYP11A1 acts, so the placenta must have another mitochondrial transport mechanism. In pregnancies with STAR mutations that result in congenital lipoid hyperplasia, altered placental steroid development is not seen.
7. Which among the following is an example of the progesterone receptor antagonist?
a) Mifepristone
b) Meristomal
c) Peristonem
d) Evecare
View Answer
Explanation: Mifepristone, also referred to as RU-486, is a drug commonly used to induce an abortion during pregnancy in conjunction with misoprostol. During the first 49 days after conception, administration of the progesterone receptor antagonist mifepristone results in abortion, indicating that progesterone is necessary for early pregnancy maintenance.
8. Which hormone is an important substrate for fetal adrenal glucocorticoid and mineralocorticoid synthesis?
a) Estrogen
b) FSH
c) LH
d) Progesterone
View Answer
Explanation: Progesterone is an essential substrate for the synthesis of foetal adrenal glucocorticoids and mineralocorticoids and for myometrial quiescence maintenance, likely by inhibiting the production of prostaglandin. Suppression of cell-mediated rejection of the foetus can play a role in the high progesterone concentrations at the trophoblast-decidua junction.
9. What is one of the major functions of hCG during pregnancy?
a) Rescue of the corpus luteum
b) Rescue of the follicular cells
c) Denaturation of endometrium
d) Nurturing placenta
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Explanation: The “rescue” of the corpus luteum during the gestation stage is one of the main functions of hCG during pregnancy. Progesterone concentrations in the serum rise for the first 6 to 7 days of the luteal process during a menstrual cycle without pregnancy, accompanied by a 3 to 4 days plateau and then a decrease that results in the endometrial lining shedding.
10. Which among the following disease includes complete and partial hydatidiform moles, choriocarcinoma, and placental-site trophoblastic tumor?
a) Gestational Morula disease
b) Gestational trophoblastic disease
c) Placental trophoblastic disease
d) Blastocyst trophoblastic disease
View Answer
Explanation: Total and partial Gestational Trophoblastic Disease (GTD) involves Hydatidiform moles, choriocarcinoma and a trophoblastic tumor at the placental site. The most common variety, occurring in 1 to 2 out of 1000 births, is full molar pregnancy. GTD does not grow from uterine cells such as cervical cancer or cancer of the endometrium (uterine lining).
Sanfoundry Global Education & Learning Series – Molecular Endocrinology.
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