Final answer:
Implantation is the process in which the blastocyst becomes embedded in the endometrium of the uterus, marking the end of the pre-embryonic stage. It typically occurs around day 8 after fertilization and takes about 5 to 7 days to complete.
Step-by-step explanation:
Implantation is the process in which the blastocyst becomes embedded in the endometrium of the uterus. It typically occurs around day 8 after fertilization and marks the end of the pre-embryonic stage of development. The blastocyst attaches to the uterine wall and begins to grow within the endometrium, ultimately leading to pregnancy. Implantation can take several days to complete, usually around 5 to 7 days. During this time, the blastocyst undergoes further development and starts to establish a connection with the maternal blood supply.