During which phase of human development does implantation of the embryo into the uterine wall normally occur?

Recognize the formation of the blastocyst: By the time the zygote reaches the uterus, it has developed into a structure called a blastocyst, which consists of an outer layer (trophoblast) and an inner cell mass that will eventually form the embryo.

Understand implantation timing: Implantation occurs when the blastocyst attaches to the uterine wall. This process typically happens about 6-7 days after fertilization, not immediately after fertilization, during ovulation, or at the end of the first trimester.