During what stage does the implantation of the blastocyst occur?

Implantation of the blastocyst occurs during the implantation stage, which is characterized by the embedding of the blastocyst into the uterine lining. This process is essential for establishing a pregnancy, as it allows the developing embryo to connect with the maternal blood supply and receive the necessary nutrients and support for growth.

During cleavage, the fertilized egg undergoes rapid cell division but does not yet involve attachment to the uterine wall. Fertilization is the initial union of sperm and egg that results in the zygote, and it occurs prior to any developmental stages. Gestation refers to the entire period of development from implantation until birth, encompassing multiple stages after implantation has already occurred. Therefore, the specific event of implantation is correctly identified in its own stage, highlighting its critical role in early embryonic development.