Effects of a mesoderm-inducing factor on early chick embryos

During recent years Tiedemann and his co-workers have developed methods for extracting and purifying neural and mesoderm-inducing factors from homogenates of 9-day-old chick embryos (see Tiedemann, 1966). One type of extract, obtained initially by phenol treatment of material precipitated with ammonium sulphate from a pyrophosphate extract of chick embryos (Tiedemann, 1959) appeared to induce mesoderm in a high proportion of cases, when implanted into Triturus gastrulae. It has been purified by chromatography on CM-cellulose (Tiedemann, 1959; Tiedemann, Kesselring, Becker & Tiedemann, 1961) and by electrophoresis on Dextran gel (Kocher-Becker, Tiedemann & Tiedemann, 1965). Triturus larvae which have received implants of mesoderm-inducing factor at the gastrula stage show extra notochord, muscle and kidney within their ventrolateral mesoderm. From the illustrations in these authors' papers, there can be no doubt at all as to the identity of these induced tissues.