Morula
A
morula is an embryo at an early stage of embryonic development, consisting of cells in a solid ball contained within the zona pellucida. The morula is produced by embryonic cleavage, the division of the zygote. Once the zygote has divided into 16 cells, it begins to resemble a mulberry, hence the name
morula. Within a few days after fertilization, cells on the outer part of the morula become bound tightly together with the formation of desmosomes and gap junctions, becoming nearly indistinguishable. This process is known as compaction. Compaction provides adaptive benefits for various species, including
Copidosoma floridanum; in the morula-stage, C. floridanum embryo invades the embryo of the host, utilizing adherent junctions to host cells. The cells of the morula then secrete a viscous liquid, causing a central cavity to be formed, forming a hollow ball of cells known as the blastocyst. The blastocyst's outer cells will become the first embryonic epithelium. Some cells, however, will remain trapped in the interior and will become the inner cell mass, and are pluripotent.