Beschreibung:
<jats:sec><jats:label /><jats:p>The extent to which tadpole cells contribute to adult tissues and organs is a long‐standing question in amphibian metamorphosis. These contributions are particularly interesting in skeletal metamorphosis, where the cartilaginous tadpole skeleton is largely replaced by <jats:italic>de novo</jats:italic> cartilage and bone formation in the adult. Three basic pathways of cellular differentiation are possible. First, larval cells may persist in a single differentiated state to give rise to an adult structure of the same tissue type (e.g. cartilage). Second, larval cells may transdifferentiate from one differentiated state to another during metamorphosis (e.g. cartilage to bone). Third, cellular progenitors to adult structures may persist as mesenchyme in the tadpole, and only achieve terminal differentiation during metamorphosis (e.g. mesenchyme to cartilage and/or bone). This project explores all three of these differentiation pathways during skeletal metamorphosis through novel transgenic labeling of cell populations and cellular lineages in <jats:italic>Xenopus laevis. Wnt1</jats:italic>, <jats:italic>sox10, col2a1</jats:italic> and <jats:italic>osterix</jats:italic> reporter constructs were used to drive green fluorescent protein (GFP) expression in the neural tube, neural crest, chondrocytes, and osteoblasts respectively. These live labels allow the visualization of skeletogenesis <jats:italic>in vivo</jats:italic>. In conjunction with cre‐recombinase‐dependent lineage labeling, these reporters reveal both the extent to which differentiated larval chondrocytes contribute to the adult skeleton, and the location of putative skeletogenic precursors that are developmentally quiescent during tadpole stages. These pathways of cellular differentiation have implications for both the mechanisms of skeletal development and the evolution of anuran metamorphosis.</jats:p><jats:p><jats:bold><jats:italic>Grant Funding Source:</jats:italic></jats:bold> <jats:italic>NSERC</jats:italic></jats:p></jats:sec>