The Substrate and Properties of Meridians: A Review of Modern Research

Meridians are regarded as the base upon which traditional acupuncture theory is built but, although much research time has been spent on their investigation, no coherent scientific theory has emerged to explain their structure or mode of action. There have been several hypotheses that offer sufficient evidence for a partial explanation for certain meridians. This paper suggests that there is indeed no single answer, but that the various hypotheses should be combined, accepting that different explanations are likely for different meridians or parts of the body. The most useful tool for investigation seems to be the phenomenon of propagated sensation along meridians. Experiments indicate that physical transmission occurs most generally through the interstitial space, specifically along the neurovascular bundles, rather than through vascular channels. The mechanism of meridian activity is likely to be via neuro-transmitters, found particularly along meridian lines, and by ionic movement. This review of research literature, much of which has emanated from China, concludes that there is a real structural basis for the meridians, but that this structure is the orderly arrangement of normal tissues along the line of meridians rather than any special histological feature.