Figure 9.

Results of phenotypic plasticity experiment (Fig. 2). Changes in mRNA levels of ventral root grafts that were transected after 30 d of forced reinnervation by sensory axons and allowed to degenerate for 7 d. Growth factors are identified as cutaneous predominant or ventral root (VR) predominant based on their upregulation after denervation of normal nerve (see Figs. 5–7). All changes were significantly different from baseline (p < 0.005). After prolonged sensory reinnervation, motor Schwann cells continue to produce PTN but also generate excessive levels of mRNA for BDNF and GDNF. Motor Schwann cells reinnervated by sensory axons thus retain a partial memory of their previous phenotype.