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 (Latin, morus: mulberry). 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[specify], 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 (the trophectoderm). Some cells, however, will remain trapped in the interior and will become the inner cell mass (ICM), and are pluripotent. In mammals (except monotremes), the ICM will ultimately form the "embryo proper", while the trophectoderm will form the placenta and other extra-embryonic tissues. However, reptiles have a different ICM. The stages are longer and divided in 4 parts.