What does a blastocyst stage in embryonic development consist of?

The blastocyst stage in embryonic development is characterized by the presence of a fluid-filled cavity known as the blastocoel. At this stage, the embryo has developed into a structure that consists of two main cell types: the inner cell mass, which will eventually form the fetus, and the trophoblast, which is the outer layer of cells that will contribute to the formation of the placenta. The blastocoel is crucial as it allows for the differentiation of the cells and the preparation for implantation into the uterine wall. This fluid-filled cavity is a defining feature of the blastocyst, facilitating further development and signaling necessary for the next stages of embryogenesis.