I have decided to investigate the question of weather or not there is a chemoattractive signal derived from the mesoderm that is able to induce overlying neural tissue to converge and extend using monopolar protrusive activity. I am working on the models of guidance in which axons are initially attracted toward a signal as they approach the midline. The attraction of the axons is later turned to repulsion as the axons get near to the midline. My question is, are these same systems at work in patterning of the neural deep cells. If so, convergence and extension is a mechanical process that is driven my diffusable molecules but such studies will be very dependent upon cloned molecules that are available to us.