Question

In human, secretion from which one of the following is used to confirm implantation of the embryo?

• A. Gastrula
• B. Trophoblast
• C. Inner mass of cell
• D. Blastocyst

Answer 1

The correct option is B Trophoblast

Implantation is the process of attachment of the blastocyst to the endometrium of uterus. During implantation, secretion of hormone (hCG, human chorionic gonadotropin, from the outer layer of syncytiotrophoblast of trophoblast) from trophoblast begins. The presence of this hormone is used as a test for knowing whether implantation has taken place or not. The secretion of this hormone can first be measured in the blood 8 to 9 days after ovulation, shortly after the blastocyst implants in the endometrium. The secretion reaches to a maximum approximately 10-12 weeks after ovulation and decreases to a much lower value by 16 to 20 weeks after ovulation.

Thus, the correct answer is option (B).