——- days after ovulation does implantation takes place?
**Core Concept**
Implantation of the fertilized ovum into the uterine endometrium is a critical process in early human development. This event occurs after fertilization, when the zygote travels through the fallopian tube and reaches the uterine cavity.
**Why the Correct Answer is Right**
Implantation typically takes place around 6-10 days after ovulation, when the blastocyst, a stage of embryonic development, adheres to the endometrial lining. This process is facilitated by the production of human chorionic gonadotropin (hCG) and the presence of specific receptors on the surface of the endometrium. The blastocyst's outer layer, called the trophoblast, invades the endometrial lining, establishing a connection for nutrient and waste exchange.
**Why Each Wrong Option is Incorrect**
**Option A:** 2 days after ovulation is too early for implantation, as the zygote has not yet reached the uterine cavity.
**Option B:** 12 days after ovulation is too late, as the blastocyst would have already implanted and begun to develop.
**Option C:** 4 days after ovulation is still within the timeframe for fertilization and early embryonic development, but implantation has not yet occurred.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that implantation typically occurs around 6-10 days after ovulation, coinciding with the luteal phase of the menstrual cycle.
**Correct Answer: C. 7 days after ovulation.**