Tsukuba, Japan—In the late 19th century, German embryologist Hans Driesch showed that when fertilized sea urchin eggs were separated at the two-cell stage, each cell could still develop into a complete organism. Yet, for more than a century, the developmental process and molecular mechanisms that allow the embryo to re-establish its body axes (anterior-posterior, dorsal-ventral, and left-right) and resume normal development have remained largely unclear.
In this study, researchers combined advanced microscopy with molecular biology to uncover how each embryo fragment is able to reset its developmental blueprint and grow into a full individual. They also succeeded in visualizing axis reconstruction by tracking the cellular movements and activation of gene that drives this remarkable self-organizing ability.
This discovery offers fresh insight into a long-standing question in life sciences: how two complete individuals can emerge from one fertilized egg. Using sea urchins as a model, it may also provide valuable insights for future developmental studies, including the origins of monozygotic twinning in humans.
