Embryoid body

Embryoid bodies are aggregates of cells derived from embryonic stem cells, and have been studied for years with mouse embryonic stem cells. Cell aggregation is imposed by hanging drop, plating upon non-tissue culture treated plates or spinner flasks; either method prevents cells from adhering to a surface to form the typical colony growth. Upon aggregation, differentiation is initiated and the cells begin to a limited extent to recapitulate embryonic development. Embryoid bodies are derived from pluripotent cells and therefore are made up of a large variety of differentiated cell types. However, the differentiation within the embryoid bodies, although occurring in a three dimensional manner is largely disorganized relative to the carefully orchestrated events of normal embryonic development. Still, embryoid bodies may serve as a good model system to investigate cellular and molecular interactions in the earliest stages of development which may be otherwise inaccessible for research, particularly in human.

The aggregate, while first simply appearing as a ball of cells, takes on an increasingly more complex appearance, becoming after a few days a hollow ball (cystic embryoid body), and next forms internal structures such as a yolk sac, and cardiomyocytes. Heart muscle cells which beat in a rhythmic pattern and neurons also commonly appear as part of the embyoid body.