Balancing self renewal and differentiation

How is self renewal and differentiation precisely balanced to accommodate growth?

Unlike the externally developing zebrafish embryo, amniotes such as mice and chickens undergo vast amounts of growth concomitantly with the formation of the embryonic body axis. The posterior body of the mouse embryo increases by approximately 65 times its initial volume during somitogenesis, this is much more that the 4 time increase in volume that occurs in zebrafish. What does this mean for the cell population dynamics between these experimental models? And, given the observed conservation in the requirement for signalling molecules and gene regulatory networks at the population level, how are these mechanisms interpreted differently at the single cell level to accommodate growth?

In addition to the continued production of progenitor cells from the posterior tip of the elongating body axis (posterior growth), a diverse set of cell behaviours could potentially drive axis elongation. We have shown that in the zebrafish for example, posterior growth is largely absent and that elongation is driven principally by a rearrangement of pre-existing cells. How flexible is the choice of cell behaviours driving axis elongation across chordates? And at what level is this divergence encoded within the system?

Comparative morphometric analysis of Posterior body elongation across vertebrates

(Steventon et al., Development 2016)

The European River Lamprey: Lampetra fluviatilis


The Small-Spotted Catshark (or Lesser-Spotted Dogfish): Scyliorhinus canicula


The Zebrafish: Danio rerio


The Mouse: Mus musculus