Question

In human female the blastocyst

• A. forms placenta even before implantation
• B. gets implanted into uterus $3$ days after ovulation
• C. gets nutrition from uterine endometrial secretion only after implantation
• D. gets implanted in endometrium by the trophoblast cell.

Answer 1

The correct option is D gets implanted in endometrium by the trophoblast cell.

The placenta forms from the trophoblast and the endometrium roughly 5 weeks after implantation. The blastocyst gets implanted in the uterus about 5-7 days after fertilisation. The implantation is via the trophoblast layer of the blastocyst that adheres to the uterine endometrium. The embryo receives oxygen and nutrition from the mother through this adhesion after implantation in the uterus. So, the correct option is 'gets implanted in endometrium by the trophoblast cell'.