The blastocyst stage is a crucial phase in early embryonic development that occurs approximately 5 to 6 days after fertilization. During this stage, the fertilized egg, now called a zygote, has undergone several rounds of cell division and forms a structure known as a blastocyst. The blastocyst consists of an outer layer of cells called the trophoblast, an inner cell mass (ICM), and a fluid-filled cavity called the blastocoel. This stage is significant as it marks the point at which the embryo is ready to implant into the uterine wall.
