The shedding and bleeding of the decidua during menses is directly caused by low levels of .....

Options

A. FSH
B. LH
C. sex steroids
D. GnRH

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the cause of shedding and bleeding of the decidua during menstruation, specifically focusing on which hormone's low levels are responsible for this process.

2. **Identifying the Decidua**: The decidua is a thick mucous membrane that lines the uterus. During menstruation, this lining is shed, leading to bleeding.

3. **Hormonal Regulation**: The menstrual cycle is regulated by various hormones, including Follicle-Stimulating Hormone (FSH), Luteinizing Hormone (LH), sex steroids (estrogen and progesterone), and Gonadotropin-Releasing Hormone (GnRH).

4. **Role of Sex Steroids**: The key hormones involved in maintaining the decidua are estrogen and progesterone, which are classified as sex steroids. These hormones are produced by the corpus luteum after ovulation.

5. **Impact of Low Hormone Levels**: If fertilization does not occur, the corpus luteum degenerates, leading to a decrease in progesterone levels. Low levels of progesterone result in the breakdown of the thickened endometrial lining (decidua), causing it to shed and resulting in menstrual bleeding.

6. **Conclusion**: The shedding and bleeding of the decidua during menses is directly caused by low levels of sex steroids, particularly progesterone.

7. **Final Answer**: The correct option is **3. sex steroids**.

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