The transmission problem in primary embryonic induction

Abstract

Earlier experimental results with radioactive tracers have indicated an incorporation of labeled material from the inductor tissue in the reacting gastrula ectoderm during induction. To test the possible specificity of this transfer of material, an inductor mixture was used in which the “mesodermalizing” principle was either not labeled or was assumed to be labeled. Differential counts of the induced mesodermal structures in the various experimental series did not show any differences, and the conclusion was drawn that an unspecific “diffusion” of labeled material occurs, at least during prolonged contact between the reactive and the active tissues. Difficulties might therefore be encountered in the employment of radioactive materials in studies related to the transfer of material during primary induction. In the other part of the present study, use was made of fluorescent antisera against a heterogenous inductor tissue to detect and localize transferred antigenic material in the ectoderm. After 3 to 6 hr of contact between the tissues, antigenic granules were obtained in abundance inside the ectodermal cells. The results demonstrate a transfer of large-molecular, antigenic material during the induction process, and show that the inductive information could be transmitted through a similar mechanism. Whether this is in fact the case cannot yet be concluded.