Which term is used to describe the hollow mass of cells that develops post-fertilization?

The term that describes the hollow mass of cells that develops after fertilization is "blastocyst." This structure forms a few days post-fertilization when the fertilized egg, or zygote, undergoes several rounds of cell division and begins to differentiate. The blastocyst comprises an outer layer of cells called the trophoblast, which will eventually contribute to the placenta, and an inner cell mass that will develop into the embryo.

In the context of human development, the blastocyst stage is crucial as it is the stage that implants into the uterine wall, allowing for further development and nurturing of the embryo. Understanding this stage is essential for comprehending the early phases of human development and the processes leading to the formation of tissues and organs.

Other terms, such as embryo and fetus, refer to different stages of development and do not specifically describe the hollow cell mass. The germ layer, on the other hand, pertains to the layers of cells in an embryo that develop into various tissues and organs, but it is not the term associated with the early hollow structure formed right after fertilization.