Insights into the regulatory architecture of the Trunk-to-Tail transition and mechanisms constraining vertebral number in mouse

The vertebral column of individual mammalian species often exhibits remarkable robustness in the number and identity of vertebral elements that form (known as axial formulae). Between mammalian species however, great diversity in axial formulae has arisen due to natural selection. This thesis investigates the underlying gene-regulatory mechanisms that unfold during mouse embryonic development to produce a robust axial formula. Specifically, the genetic manipulation of Gdf11, Retinoic acid and microRNA-196 activity, individually and cumulatively, led to the formation of additional vertebral elements. Moreover, this work revealed a highly unexpected role for posterior Hox genes in supporting the growth of tail structures.