Embryonic pattern specification during development in some cases requires maternally contributed ‘determinants’, and in others is regulated by signaling between cells. For each of the following developmental events, indicate whether it is primarily maternally contributed determinants or instead local interactions between cells that is most important. In addition, name one important gene involved in each process.

• (a) Germ cell specification in Drosophila

• (b) Neural Crest Cell specification in vertebrates

• (c) Anterior/Posterior border specification in Drosophila wing imaginal disk