Morula (Molecular Biology)

The morula is a stage during early embryonic development in embryos with holoblastic cleavage, where there is little yolk and the entire zygote is involved. After fertilization, the cleavage furrows in holoblastic embryos completely separate the cells. After a few divisions, the cell mass forms a small ball that resembles a mulberry (morula is Latin for mulberry). As the cleavage divisions continue, a hollow space called the blastocoel forms with a single layer of cells surrounding it. This stage is called the blastula stage.