Final answer:
The blastocyst, including the inner cell mass, forms around 5 days after fertilization and implants into the endometrium lining the uterus.
Step-by-step explanation:
Following fertilization, a blastocyst with an inner cell mass emerges about 5 days into embryonic development. Originating from the morula, this complex structure encompasses both a trophoblast outer layer and an inner cell mass, the latter holding crucial significance for future differentiation. The blastocyst embarks on a journey, reaching the uterus approximately 4 to 5 days post-fertilization. The subsequent implantation process involves the blastocyst integrating into the endometrial lining, a pivotal event in early embryogenesis. This orchestrated sequence sets the stage for subsequent stages of embryonic growth and specialization, laying the groundwork for the intricate development of a new life.