Figure 1.

A: Growth cone is mostly made up of microtubule cytoskeleton and Filamentous actin (F-actin). The orientation of the advancing tip is guided by gradients of neurotrophic factors produced mainly by non-neuronal cells. The extracellular matrix (ECM) and cell adhesion molecules (CAMs) influence the state of the regenerating neurons and determine the response of the growth cone. B: Schwann cells (SCs) undergo dedifferentiation, proliferation, migration and remyelination after peripheral nerve injury. Differentiated Schwann cells transformed into repaired Schwann cells (rSCs). Proliferation of SCs can upregulate regeneration-associated genes, promote the aggregation of macrophages and clear myelin sheath debris. SCs form Bunger bands in the basement membrane tube and secrete a variety of neurotrophic factors. Under the support, guidance and stimulation of them, the growth cone extends from the proximal end to the distal target in the correct direction, and finally achieves nerve re-innervation.