Neural crest cells (NCCs) give rise to various tissues, including pigment cells and certain neurons. They arise from the embryonic dorsal neural tube(NT) through a so-called epithelial-mesenchymal transition (EMT), during which polarised neuroepithelial cells turn into mesenchymal cells that emigrate from the NT. NCC EMT is generally thought to occur via a linear cascade of events,but on ,Ahlstrom and Erickson report findings that challenge this assumption. The authors tracked chick NCCs undergoing EMT through confocal time-lapse imaging and observed that although most NCCs detach from the NT lumen, retract their tail and translocate their cell body out of the neuroepithelium, this is not what happens in all cells. The order of events might vary, the tail might be ruptured instead of retracted, or cell body translocation might occur when the cell is morphologically rounded up during cell division. Based on these and other findings, the authors propose that EMT-associated events are mainly independently regulated and only cooperate loosely to allow NCC emigration from the NT.
