The first pure embryonic inducing factor.

Abstract

This is a personal account of the discovery of the mesoderm-inducing activity of fibroblast growth factors. The background is my work on the dorsalising signal in early amphibian embryos that was done at the imperial Cancer Research Fund in London. I became interested in mesoderm induction because of the embryologic work of Nieuwkoop and the partial purification of a "vegetalising factor" by Tiedemann. Although, initially, we expected inducing factors to be novel substances, it gradually became clear that the impure preparations we were studying had properties in common with growth factors. This opened the way to the testing of candidate factors, resulting in the conclusion that some inducing factors and growth factors,in fact, were the same molecules despite being discovered through different routes and assayed using different methods. After a slow start looking at the molecular biology of fibroblast growth factors in Xenopus, we eventually found that their most interesting functions in early development lay not at the stage of mesoderm induction but, rather, in the anteroposterior patterning of the body, which occurs during gastrulation.