Final answer:
Implantation takes place during the germinal stage of prenatal development, which lasts from fertilization until about 8 to 9 days later when the blastocyst implants in the uterus, marking the beginning of the embryonic stage.
Step-by-step explanation:
Implantation occurs during the germinal stage of prenatal development. This stage begins with fertilization, usually taking place in the Fallopian tube, and ends with the implantation of the blastocyst into the endometrium of the uterus. The germinal stage is comprised of the development of the zygote into a morula and then into a blastocyst over the course of approximately one week. After about 8 to 9 days, the blastocyst completes its journey from the Fallopian tube to the uterus where it adheres to the uterine wall, signaling the end of the germinal stage and the start of the embryonic stage of prenatal development.
It is during this period that the blastocyst may sometimes fail to implant, leading to a natural end of the potential pregnancy. However, successful implantation results in the formation of an embryo, which will begin to obtain nutrients from the mother's blood via the placenta and undergo further significant growth and changes in the following stages.