text: Lancaster and Knoblich define an organoid as a collection of organ-specific cell types that develops from stem cells or organ progenitors, self-organizes through cell sorting and spatially restricted lineage commitment in a manner similar to in vivo, and exhibits the following properties: 
  * it has multiple organ-specific cell types;
  * it is capable of recapitulating some specific function of the organ (e.g. contraction, neural activity, endocrine secretion, filtration, excretion);
  * its cells are grouped together and spatially organized, similar to an organ.