 Signals sent between the follicular cells and the oocyte (such as factors similar to epidermal growth factor) cause the reorganization of the microtubules so that their (-) ends are located in the lower part of the oocyte, polarizing the structure and leading to the appearance of an anterior-posterior axis.This involvement in the body's architecture is also seen in mammals.Another area where microtubules are essential is the development of the nervous system in higher vertebrates, where tubulin's dynamics and those of the associated proteins (such as the microtubule-associated proteins) is finely controlled during the development of the nervous system.