During third week of development, pre-notochordal cells invaginating inside the primitive pit move forward and cephalad upto prechordal
We made the observation that early cell populations extrinsic to the heart fields arising during gastrulation, specifically the prechordal
plate cells [61-64], were susceptible to environmental lithium exposure and failed to contribute in normal numbers to a cell population that localizes to the ventral floor of the foregut and that contributes to the dorsal mesenchymal protrusion (DMP) region .
Finally, the scientists determined that a nearby piece of the embryo, the prechordal
mesoderm, induces the single region to split.
For instance, in vertebrates the formation of epidermal or neural ectoderm depends upon the presence of the prechordal
and chordal mesoderm (Nieuwkoop 1952).