Development of a laparoscopic system for in vivo observation of the Bonghan structure.

Bonghan structures composed of corpuscles and ducts have been observed in numerous animal experiments. The structure has been suggested to be the physical substrate for acupuncture points and meridians used in traditional Chinese medicine. The corpuscle-duct structure on the organ surface has been extensively studied. However, it was only observed after the abdomen of a rat was fully exposed. It may be desirable to observe these structures under minimally invasive conditions. Our laparoscope is specifically designed for in situ, in vivo observation of the Bonghan structure on the surface of internal organs in rats. We made a laparoscope consisting of a borescope combined with an illumination module and an imaging data acquisition part. The Bonghan structure is transparent and is hard to see, even with the borescope. Spraying a specific dye, trypan blue and washing with saline is a necessary process to visualize the structure. For this reason, we devised a staining and washing system attached in parallel with the borescope in the laparoscopic system. The system operated successfully to reveal a Bonghan structure without surgery. This tool opens a host of possible applications such as observation of flow of stained liquid or drug in the Bonghan duct flowing from the skin to internal organs, and long-term observation of the physiological changes in Bonghan corpuscles.