Question

Which of the following hormones is not produced by the placenta?

• A. \( \text{hCG} \)
• B. \( \text{hPL} \)
• C. \( \text{Thyroxine} \)
• D. \( \text{Estrogen} \)

Hint:

Placenta mainly secretes hCG, hPL, Estrogens, and Progesterone, whereas Thyroxine is secreted by the thyroid gland.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The placenta is a temporary endocrine organ formed during pregnancy that facilitates nutrient, waste, and gas exchange between the mother and the developing fetus. In addition to transport, it synthesizes and secretes several crucial hormones necessary for maintaining pregnancy, supporting fetal development, and preparing the maternal body for lactation.
Step 2: Detailed Explanation:
Let's analyze the origins of each hormone mentioned in the options: - hCG (Human Chorionic Gonadotropin): Produced almost exclusively by the syncytiotrophoblast cells of the placenta shortly after implantation. It prevents the degradation of the corpus luteum to keep progesterone production stable. - hPL (Human Placental Lactogen): Synthesized and secreted by the placenta. It regulates maternal metabolism, ensuring a steady supply of glucose and nutrients reaches the fetus. - Estrogen and Progesterone: In the later stages of pregnancy, the placenta takes over the production of these steroid hormones from the ovary to maintain the uterine lining. - Thyroxine ($T_4$): This is a primary metabolic thyroid hormone produced and released exclusively by the maternal and fetal thyroid glands, not by the placenta. Because thyroxine is produced by the thyroid gland, it is the correct answer to this negative selection question.
Step 3: Final Answer:
Thyroxine is not produced by the placenta, matching option (C).