So far, neither has proved medically useful. In the April issue of the journal Tissue Engineering , a team from the University of Pennsylvania reported a fundamentally new approach. Douglas H. Smith, M.D., and John A. Wolf, B.S., of the Department of Neurosurgery and Whitaker Investigator David F. Meaney, Ph.D., of the Department of Bioengineering said this is the first evidence that the connecting threads between nerve cells will grow when stretched. They also found no reason why the cells would not grow longer if they kept pulling on them. Their findings appear consistent with what happens to the central nervous system in children as they mature.
Nerve cells grow and multiply and connect with one another by way of long extensions called axons.
Most of this activity occurs in the embryo. By the time a child is 2, new connections stop forming. But, of course, children continue to grow. As they get taller, their axons get longer. The researchers believe that axons grow from their midsections in response to the mechanical tension of the growing organism.