Inducing activity of fractionated microsomal material from theXenopus laevis gastrula stage.

The postmitochondrial supernatant fromXenopus gastrulae has been fractionated on sucrose gradients. Part of the microsomal material was treated with EDTA, which dissociates most of the polysomal and monosomal material into ribosomal subunits. In addition, a series of pooled fractions from the EDTA treated gradients has been applied to discontinuous gradients in more concentrated sucrose to separate membranous material from the remaining microsomal components.

[Inducing capacity of subcellular fractions from the gastrula ofXenopus laevis].

Isolated yolk platelets, nuclei and pigment granules, ribosomes and the ribosome-free supernatant of homogenates from whole gastrulae ofXenopus laevis were tested for their inducing properties.The subcellular fractions were obtained by differential centrifugation in sucrose media and their purity was checked by electronmicroscopy.The microsomal fraction shows archencephalic and deuterencephalic inducing capacity which is enhanced after extraction with pyrophosphate and with phenol.

[The induction capacity of dorsal lips tested by xenoplastic operations].

Xenoplastic implantation of dorsal lips according to the insertion and sandwich technique shows the following results using the two speciesXenopus laevis andAmbystoma mexicanum: 1. The percentage frequency of fore head and hind head inductions is in general higher than that of mesodermal inductions. 2.