Fig. 3. Schematic representation of eBC formation in the MPS. (A) Schematic of the differentiation and isolation of hESCs into immature insulin producing clusters from day 0 through day 20 is shown in the upper panel. INS^GFP+ cells were isolated by FACS from day 20 clusters, and singularized INS^GFP+ cells were introduced into the microwell arrays within the MPS via the cell loading access ports. In situ reaggregation of enriched β cell clusters (eBCs) was observed within a 72-hour period (GFP marks insulin producing cells). (B) Histogram of the cluster sizes measured in the MPS microwell arrays.