Embryoid Bodies as Models of Embryogenesis

Philadelphia, Pennsylvania -

Cellular positioning during embryogenesis is a complex process involving numerous soluble and cell surface bound factors. A recent paper (Rula et al. Cell autonomous sorting and surface positioning in the formation of primitive endoderm in embryoid bodies. Genesis. 2007 May 15;45(6):327-338) using artificially generated embryoid bodies to further investigate this process.

The researchers where interested in movement of endodermal-committed cells (endoderm gives rise to stomach, colon, liver, pancreas, urinary bladder; lining of urethra, epithelial parts of trachea, lungs, pharynx, thyroid, parathyroid, and intestine) during development.

It was found that endodermal cells are first located in the middle of the embryoid body and that they eventually migrate to the surface. When embryoid bodies were dissociated and cells mixed, it was found that this migration still occurred, implying that surface positioning was intrinsically programmed in the endodermal cells. Cells in which expression of the gene Disabled-2 was knock-out did not express ability to migrate to the surface.

Another interesting finding was that the adhesion molecule E-cadherin was not essential for endodermal cell migration.

This study demonstrates the utility of the embryoid body as a model for embryogenesis.

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