Question

Which among the following hormones is not produced by placenta?

• A. Human Chorionic Gonadotropin (hCG)
• B. Human Placental Lactogen (hPL)
• C. Estrogens
• D. Relaxin

Hint:

Important placental hormones: \[ \text{hCG, hPL, Estrogens, Progesterone} \] Relaxin is mainly secreted by the corpus luteum.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The placenta functions as a temporary endocrine link between the mother and the fetus. It creates various specialized hormones required to adjust maternal physiology and prevent pregnancy loss. However, certain hormones associated with pregnancy are primarily synthesized inside maternal ovarian tissues instead.
Step 2: Detailed Explanation:
Let's evaluate the primary synthesis sites for each listed hormone: - hCG (Option A): Secreted exclusively by the placental trophoblast tissue to maintain the corpus luteum during early pregnancy. - hPL (Option B): Synthesized exclusively by the placenta to alter maternal carbohydrate and lipid metabolism, directing glucose to the fetus. - Estrogens (Option C): Secreted in massive amounts by the placenta during the second and third trimesters to increase uterine blood flow and stimulate breast tissue growth. - Relaxin (Option D): In human females, relaxin is primarily produced and secreted by the corpus luteum of the ovary during pregnancy (and to a much lesser extent by the decidua, rather than the true placenta). It functions to relax the pelvic ligaments and soften the cervix to ease childbirth. Since relaxin is mainly an ovarian hormone product rather than a true placental secretion, it is the correct choice.
Step 3: Final Answer:
Relaxin is not primarily produced by the placenta, matching option (D).