AN ESSAY ON THE SIMILARITIES AND DIFFERENCES BETWEEN INDUCTIVE INTERACTIONS IN ANURAN AND URODELE EMBRYOS

As a first step towards providing a conceptual approach to understandi ng similarities and differences in the mechanisms which guide inductiv e interactions among related organisms (e.g. various amphibia), a set of five principles is offered here. These principles were formulated b y analyzing literature examples of classical embryological phenomena a nd by performing experiments with activin, a peptide growth factor whi ch is currently suspected to play for a role in mesoderm induction. Me chanisms which account, at least in part, for the observed differences between anuran and urodele inductive processes can be derived from th ese principles.