What is the structure that forms from the fertilized egg before implantation?

The structure that forms from the fertilized egg before implantation is the zygote. After fertilization occurs, the sperm and egg cells fuse to form the zygote, which is a single-cell entity. This zygote immediately begins a series of mitotic divisions as it moves through the fallopian tube towards the uterus.

During this journey, the zygote undergoes cleavage, resulting in a multicellular structure before it reaches the stage of implantation. It is crucial to recognize that while the zygote represents the very first cell formed after fertilization, it will eventually develop into a blastocyst as it continues to divide and differentiate. The blastocyst is the stage that implants into the uterine wall, marking the transition from a fertilized egg to an embryo.

Understanding the timeline and stages of development from zygote to blastocyst highlights the importance of the zygote as the starting point of this developmental process.