Essential Experimental Methods for Identifying Bonghan Systems as a Basis for Korean Medicine: Focusing on Visual Materials from Original Papers and Modern Outcomes

In the 1960s, through studies on Korean Medicine, Bonghan Kim proposed the Bonghan systems (BS) as the anatomical reality of the acupuncture meridians based on various experimental data. Since 2002, several groups, mainly led by a team at Seoul National University, who renamed the BS as the primo vascular system (PVS), have published around 70 papers showing biological structures corresponding to the BS. However, it is still difficult for other researchers to find them, especially under the skin, which Bonghan Kim first reported as acupuncture points, due to similar-looking biological tissues, for example, the lymphatic vessels, and such artifacts as blood clots or fascia debris. To solve these drawbacks, we examined the main methods for identifying the BS by comparing the original papers with the modern outcomes in terms of the common physical/chemical characteristics of the BS. In addition, effective methods of staining and microscopic observations discovered by modern teams are synthetically explained using visual materials such as diagrams and photos. Through the essentially organized methods in this review paper, we suggest that one can find the BS under the skin as putative acupuncture points by tracing the intraexternal BS, from which a new Korean Medicine will be born.