Which of the following statements about the secretion of human chorionic gonadotropin (hCG) is accurate?

• A. hCG secretion begins only after the second trimester of pregnancy.
• B. hCG is secreted by the corpus luteum throughout the entire pregnancy.
• C. hCG is produced by the anterior pituitary gland during ovulation.
• D. hCG is secreted by the trophoblast cells of the early embryo after implantation.

Answer: (D)

Verified step by step guidance

1. Understand the role of human chorionic gonadotropin (hCG): hCG is a hormone critical for maintaining pregnancy. It signals the corpus luteum to continue producing progesterone, which is essential for maintaining the uterine lining during early pregnancy.
2. Identify the source of hCG secretion: hCG is secreted by trophoblast cells, which are part of the early embryo. These cells form the outer layer of the blastocyst and later contribute to the formation of the placenta.
3. Clarify the timing of hCG secretion: hCG secretion begins shortly after implantation of the blastocyst into the uterine wall, which typically occurs around 6-10 days after fertilization. It does not begin in the second trimester, as suggested by one of the incorrect options.
4. Eliminate incorrect options: hCG is not secreted by the corpus luteum throughout pregnancy; instead, the corpus luteum is maintained by hCG in early pregnancy. Additionally, hCG is not produced by the anterior pituitary gland during ovulation; this is a misunderstanding of its origin and function.
5. Conclude with the correct statement: The accurate statement is that hCG is secreted by the trophoblast cells of the early embryo after implantation, as this aligns with the biological role and source of hCG.