Major Decisions in Building the Embryo

Binary decisions:

These decisions happen at a single developmental stage, and have irreversible fate determination.

Some examples include:

- - sex establishment

- - separation of germ line from the soma

Complex Decisions:

Almost only somatic cells are involved in these decisions.

The decisions are taken by the local population of cells

Some examples include:

-        -- positional and orientation information (anterior/posterior and dorsal/ventral)

- - the development of segments in the ant/post direction, and associated roles for each segment

- - development of germ layers in the dorsal/ventral axis and associated roles for each germ layer

- - the production of organs, tissues, systems and appendages