Development. PARallels in axis formation

Abstract

There is an intricate network of molecules called cell fate determinants that instruct the cells of the embryo to take on either an anterior or posterior fate. In a lively Perspective, Lehmann and her colleagues discuss new findings in the fruit fly that identify a key protein, PAR-1, which ensures that the cell fate determinants are themselves located in the correct region of the oocyte. In this way, the anterior-posterior axis is set up in the fruit fly egg before fertilization.