EBs, creating gradients of morphogens, metabolites, and nutrients. It has been estimated that oxygen transport is limited in cell aggregates larger than approximately 300 µm in diameter; however, the development of such gradients are also impacted by molecule size and cell uptake rates. Therefore, the delivery of morphogens to EBs results in increased heterogeneity and decreased efficiency of differentiated cell populations compared to monolayer cultures. One method of addressing transport limitations within EBs has been through polymeric delivery of morphogens from within the EB structure. Additionally, EBs can be cultured as individual microtissues and subsequently assembled into larger structures for tissue engineering applications. Although the complexity resulting from the three-dimensional adhesions and signaling may recapitulate more native tissue structures, it also creates challenges for understanding the relative contributions of mechanical, chemical, and physical signals to the resulting cell phenotypes and morphogenesis. See also Brain organoid Gastruloid Induced stem cells Pluripotency References Stem cells Articles containing video clips