At what point does the zygote develop into an embryo?

The zygote develops into an embryo after implantation occurs in the uterus. After fertilization of the egg by the sperm, the zygote undergoes several divisions and develops into a blastocyst. This blastocyst then travels down the fallopian tube to the uterus, where it implants into the uterine lining. Once this implantation is successful, the cells begin to differentiate, and the structure is officially referred to as an embryo. This stage marks the beginning of the development of the new organism, where it will begin to form essential structures and systems.

In contrast, fertilization occurs before implantation, which eliminates the possibility of earlier points in the reproductive process being the correct answer. Similarly, ovulation and menstruation do not relate to zygote development, as they pertain to the release of eggs and the shedding of the uterine lining, respectively, and do not involve the embryo at all.