Insights into how complex tissues self-organise
Even the most complex organs begin as clumps of cells. Developing their shapes requires careful organisation. Researchers now investigate by growing organ-like tissues (organoids) from mouse embryonic stem cells and using quantitative microscopy (pictured) to image their cell surfaces (white) and cell-cell boundaries (green). The organoids formed tissues called neuroepithelia using two mechanisms: fusing together two separate masses of epithelia (trans fusion) and fusing together two ends of the same epithelium (cis fusion). Organoid shape was determined by these rates of fusion. The team were able to control these rates by adding the chemical retinoic acid (RA). Over several days without RA (top), cis fusion dominated, resulting in each organoid forming one large fluid-filled cavity with multiple passages leading into the cavity from the outer surface. With RA, trans fusion dominated, leading to organoids with multiple cavities (bottom). Together, this model provides insights into how complex tissues self-organise.
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