Fertilized ovum is implanted into uterus after
A. 7 days
B. 1 days
C. 8 days
D. 10 days
Correct Answer : A. 7 days
Explanation
The fertilized ovum (now a blastocyst) is implanted into the uterus about 6–7 days after fertilization.
Key points
• Fertilization occurs in the ampulla of the fallopian tube.
• The zygote undergoes cleavage as it travels toward the uterus.
• By day 5, it becomes a blastocyst.
• Implantation begins around day 6–7 after fertilization and completes by day 10–12.
One-line answer
👉 Implantation occurs approximately 6–7 days after fertilization.
Other Options Details
Here is an explanation of each option regarding when a fertilized ovum (blastocyst) implants into the uterus:
A. 7 days
• This is the most accurate and commonly accepted time for implantation.
• After fertilization in the ampulla of the fallopian tube, the zygote undergoes cleavage, forms a morula, and then becomes a blastocyst by day 5–6.
• The blastocyst reaches the uterus around day 4–5 and begins implantation around day 6–7 after fertilization.
👉 Correct answer in most textbooks = 7 days
B. 1 day
This is incorrect.
• It is far too early for implantation at this stage.
• On day 1, the zygote has just undergone its first cleavage division and is still in the fallopian tube.
C. 8 days
This is near-correct and may be accepted in some references.
• Implantation starts around day 6–7, but complete embedding typically finishes by day 9–10.
• Therefore, implantation activity can continue around day 8, but it does not start here.
D. 10 days
Partially correct but late for the start of implantation.
• By day 10, the blastocyst is usually completely embedded within the endometrium and the lacunar stage of placenta formation is underway.
• So day 10 refers to completion, not initiation of implantation.
Summary
Option Description Correct?
A. 7 days Typical time for implantation to begin Best answer
B. 1 day Too early, still in tube
C. 8 days Possible during ongoing implantation Near-correct
D. 10 days Time when implantation completes Completion stage
Final Correct Answer: A. 7 days
I hope that you liked this article.
Thanks!! 🙏 😊
Writer: Vandita Singh, Lucknow (GS India Nursing Group)