To become a embryo.
Blastocyst formation
When an embryo (fertilized egg) reaches the uterus, it is a hollow ball of about 100 cells called a blastocyst.
They make up the placenta that provides the blastocyst with nutrients.
A 5 day blastocyst will be 0.1 to 0.2 milleters (.003 to .005 inch) typically
Blastocyst. Each of those cells will eventually become a different part of the baby's body as they each multiply, creating muscle, bone, and organ tissues.
No they do not.
Blastocyst
About 100 cells make up a blastocyst.
a few days after fertilization
Gastrulation
at the end of the first trimester
It became a blastocyst