ERICSSON, R; FALCK, P; JOSS, J; OLSSON, L: Development of the Larval Head in Australian Lungfish and Mexican Axolotl

Development of the larval head in Australian lungfish and Mexican axolotl. Lungfishes are the extant sister group to tetrapods, so a comparison of lungfishes and salamanders span the transition from a totally aquatic to a biphasic life-history mode. This was one of the major steps in vertebrate evolution and affected the development and morphology of many organ systems. Very little is known about head development in the Australian lungfish. We have falsified the notion that migrating cranial neural crest cells are completely missing in the Australian lungfish. Instead, the number and identity of cranial neural crest streams are very conserved features between Australian lungfish and amphibians. We now work on elucidating the migration and fate of cranial neural crest and head paraxial mesoderm cells in Australian lungfish and Mexican axolotl, using fluorescent dyes, gene expression patterns, extirpation experiments, confocal microscopy and 3D- reconstruction. This will shed light on the developmental processes underlying differences in larval head anatomy between lungfish and axolotl and lead to a better understanding of the development and evolution of vertebrate head segmentation.