Visualization of acupuncture meridians in the hypodermis of rat using Trypan blue

Bonghan Kim claimed that the primo-vessel (Bonghan duct) and the primo-node (Bonghan corpuscle) are anatomical structures corresponding to acupuncture meridians and acupoints, respectively, but this claim has not been confirmed. Recently we found that Trypan blue preferentially stained primo-vessels and primo-nodes on the surfaces of internal organs, not staining other structures like blood or lymph vessels or nerves. In this work, we applied Trypan blue to visualize the putative acupuncture meridian along skin skeletal muscles in the hypodermal layer of a rat. The Trypan blue stained-structures are morphologically similar to the meridian primo-vessels, as claimed by Bonghan Kim. Further study is needed to investigate the network of these Trypan blue-stained structures in order to establish them as acupuncture meridians.