Answer:
Blastocyst
Step-by-step explanation:
Once an egg is fertilized by a sperm, it begins to divide by mitosis into a 2, 4, and then 8 celled structure. Eventually, this large collection of cells keeps dividing and becomes a hallow collection of undifferentiated cells called a blastocyst. The blastocyst will implant on the wall of the uterus where it will begin to grow and develop during pregnancy into a fetus.