The Influence of Brain-Skull Interactions on the Development of the Amphibian Skull

The tetrapod skull has evolved in response to various pressures over its long evolutionary history - one pressure being the expansion of the cerebral hemispheres. The molecular basis of these brain-skull interactions remains incompletely understood, though studies indicate that key to this relationship is the biochemical signaling sources within the forebrain. One method of eliminating local signals is tissue removal/ablation. To better understand these brain-skull interactions, forebrain removal experiments were conducted in Xenopus laevis, a representative of the poorly studied amphibians, to study the resulting skull morphology. To facilitate these comparisons, a detailed internal staging guide for X. laevis was developed. It was found that removal of forebrain tissue in early tailbud embryos resulted in craniofacial deformities, as well as a disruption to sensory development. These findings indicate that the role of the forebrain in craniofacial development seen in amniotes is likely conserved in X. laevis.