After fertilization, implantation blessing usually occurs after approximately how many days?
A. 20-28 days B. 6-12 days C. 14-18 days D. 2-4 days
Correct Answer: B. 6-12 days
Explanation
After fertilization, implantation (also called nidation) is the process by which the blastocyst attaches to the uterine endometrium. Let us explain all the options clearly and then identify the correct one.
Options Explained
A. 20–28 days ❌
- This time period corresponds roughly to the length of a menstrual cycle, not implantation.
- Implantation occurs much earlier, so this option is incorrect.
B. 6–12 days ✅ (Correct Answer)
- After fertilization (which occurs in the ampulla of the fallopian tube), the zygote undergoes cleavage → morula → blastocyst.
- The blastocyst reaches the uterus around day 4–5.
- Implantation usually begins between day 6–7 and is completed by day 10–12 after fertilization.
- Therefore, this is the correct answer.
C. 14–18 days ❌
- By this time, implantation is already completed, and early placental development has begun.
- Hence, this option is incorrect.
D. 2–4 days ❌
- During this period, the fertilized ovum is still traveling through the fallopian tube and is in the cleavage stage.
- Implantation cannot occur at this stage, so this option is incorrect.
Final Answer
✔ Implantation usually occurs approximately 6–12 days after fertilization.
Other Options Details
Question:
After fertilization, implantation usually occurs after approximately how many days?
Implantation is the process by which the blastocyst attaches to and embeds in the endometrium (uterine lining). It occurs after the fertilized ovum travels through the fallopian tube and reaches the uterus.
Option A. 20–28 days
- This time frame corresponds roughly to the length of the menstrual cycle, not implantation.
- Implantation does not occur this late after fertilization.
- ❌ Incorrect
Option B. 6–12 days ✅ Correct answer
- Fertilization occurs around day 14 of the menstrual cycle.
- The embryo reaches the uterus as a blastocyst in about 5 days.
- Implantation typically begins around day 6–7 after fertilization and is usually completed by day 10–12.
- ✔ This is the correct and accepted time period
Option C. 14–18 days
- This period refers more to days after the start of the last menstrual period (LMP), not days after fertilization.
- Implantation has usually already occurred by this time.
- ❌ Incorrect
Option D. 2–4 days
- At 2–4 days after fertilization, the embryo is still in the cleavage stage (2–8 cell stage).
- It is still in the fallopian tube, not yet ready for implantation.
- ❌ Incorrect
✅ Final Answer:
B. 6–12 days
📌 Implantation usually occurs about 6–12 days after fertilization, when the blastocyst embeds in the uterine wall.
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Writer: Vandita Singh, Lucknow (GS India Nursing Group