Abstract

Body segments are formed during axial elongation in most bilaterian animals (i.e. in annelids, arthropods and vertebrates). Understanding the dynamic coordination between the different cell behaviors and the apparently conserved molecular mechanisms involved in both simultaneous processes (segmentation and elongation) has demonstrated not to be trivial. Within the last decades, diverse microscopy and embryonic techniques, as well as genetic and molecular tools have been developed, giving the possibility to show us segmentation and axial elongation in motion, that has allowed researchers to demonstrate processes hardly proved without live imaging, to match cell behaviors with molecular mechanisms and to put experimental results into a developmental context. When many hours of development are compressed into a few seconds, dynamic phenomena are manifested. This chapter highlights the contributions of the relatively new incorporation of live imaging microscopy into this topic.