Fig. 6.

A working model on the graded response to axonal injury. For axons that have multiple orders of branches, an injury to the primary, secondary, tertiary etc. branch would elicit a response of different strengths. Injury to a lower order branch would generally elicit a stronger response as compared with a higher order branch. A strong response could be a strong regenerative response or cell death, depending on other cellular context. A weak response would be self-preservation without a detectable regenerative response. A spectrum of intermediate responses are possible.