Extracellular matrix and neural determination during amphibian gastrulation.

Previous studies have shown the presence of a network of extracellular matrix on the inner surface of the ectoderm of the early gastrulae Pleurodeles waltlii. Similar dense networks have been described by other authors in another Urodele species and in Anurans. It now seems well established that this extracellular material (ECM) has important functions in the mechanisms of morphogenetic cell movements during gastrulation. The results reported here provide evidence that this ECM is not implicated in the transmission of the neuralizing signal at the gastrula stage, and therefore is not involved in the process of neural determination.