AXONAL SPROUTING AT THE NODE OF RANVIER OF THE PERIPHERAL-NERVE DISCONNECTED WITH THE CELL BODY

In order to examine whether the axonal sprouting at the node of Ranvie r is a local event reactive to the lesion independent of influences fr om the cell body, the sciatic nerve of mouse (ddY strain) was freeze-i njured at the mid-thigh and at the same time transected at the level 2 cm proximal to the frozen site. Within 5 h after freeze-transection, sprouts were formed at some nodes of Ranvier located within 0.5 mm pro ximal to the frozen site. These sprouts had almost the same ultrastruc tural features as those found in ordinary freeze-injury, showing a ten dency to grow toward the overlying Schwann cell basal lamina. However, the sprouts thus formed ceased to grow and became atrophic within 10 h after freeze-transection. This fact indicates that the axon has a pr operty of sprouting at the node of Ranvier in the absence of the cell body. However, nutritional as well as constitutive substances from the cell body are needed to maintain the growth of the sprout.