Conditional Specification of Cell Fate is characteristic of all vertebrates and a few invertebrate species.
Conditional specification is a consequence of interactions between cells.
Hence position is important. Embryos that exhibit conditional specification have variable cleavage patterns. Typically, cell rearrangements and migrations precede or accompany specification. Embryos that display conditional specifation also display regulative development to some degree. Induction of the Mesoderm in Amphibians Fate map information is the starting point for any analysis of cell fate specification and determination.