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Difficulty: Very hardReproductive Systems and Processes in Organisms

In human female reproductive physiology, early implantation of the blastocyst produces human chorionic gonadotropin (hCG). Which of the following best describes the direct physiological role of hCG in maintaining early pregnancy?

  1. It preserves the corpus luteum, ensuring continuous secretion of progesterone to maintain the endometrial lining.Answer
  2. B
    It stimulates the anterior pituitary to increase follicle-stimulating hormone (FSH) secretion for new follicular growth.
  3. C
    It directly triggers luteolysis to rapidly transfer hormone production to the developing uterine wall.
  4. D
    It suppresses estrogen release while directly stimulating uterine oxytocin receptors to suppress contractions.

Answer

The correct option is the statement that human chorionic gonadotropin preserves the corpus luteum, ensuring continuous secretion of progesterone to maintain the endometrial lining.
Human chorionic gonadotropin (hCG) binds to LH receptors on the corpus luteum, rescuing it from involution. This ensures sustained synthesis of progesterone, which maintains the uterine endometrium in a receptive, secretory state essential for embryo survival.

Step-by-Step Solution

1
Identify the origin and primary target of human chorionic gonadotropin (hCG) post-implantation.
hCG is secreted by the trophoblastic cells of the developing embryo and acts on the corpus luteum in the ovary.
Understanding the endocrine axis between the early embryo and the maternal ovary is critical for determining hormone function.
2
Analyze the hormonal signaling required to prevent menstruation during early pregnancy.
hCG prevents the degeneration of the corpus luteum, which continues producing progesterone and estrogen.
Progesterone maintains the vascularized stratum functionalis of the endometrium and prevents uterine contractions.
3
Evaluate the distractors regarding pituitary regulation and luteolysis.
Options proposing FSH stimulation, luteolysis initiation, or estrogen suppression represent incorrect physiological mechanisms.
Pituitary gonadotropins are suppressed via negative feedback during pregnancy, and luteolysis would terminate pregnancy.

Key Concept

Hormonal control of the female mammalian reproductive system and early pregnancy maintenance
Estimated Time:1m 30s
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Topics

Reproductive Systems and Processes in Organisms

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