As gastrulation continues, further spreading of the blastocoel floor by upward movement of vegetal cells contributes to the advancement of the mesendoderm along the blastocoel roof.
Upon reaching the pluteus stage (24 hours post fertilization), an abundance of extracellular matrix is also found associated with the syncytia and blastocoel wall.
The morula's cells differentiate into two types: an inner cell mass growing on the interior of the blastocoel and trophoblast cells growing on the exterior.