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

Figure 2

The neural Bonghan systems. (A) The neural Bonghan systems determined by the Bonghan research team. Diagrams and a photo of the neural Bonghan systems. In the central nervous systems, the Bonghan ducts (a, b) are distributed in the brain and spinal cord in a free state through the cerebral ventricles, the central canal, and the subarachnoid space along the circulating route of the cerebrospinal liquor. In addition, they enter under the perineurium and between the nerve fibers in the peripheral nervous systems. The Bonghan duct in the central canal of the spinal cord (c) is surrounded by unknown tissues [5]. (B) The Bonghan ducts and corpuscles on the surfaces of the brain stained by Alcian blue. Illustration of a network of the Bonghan ducts (PV) and corpuscles (PN) above the pia mater of the brain and the spine of rats stained by Alcian blue under a stereomicroscope. Stereoscopic images are visualized by spraying Alcian blue into the pia mater of the brain (a, b) and by injecting it into the lateral ventricles (c, d, e). The red-colored blood vessels are not stained (a, b, c). All scale bars are 500 μm [18]. (C) The Bonghan duct in the brain ventricles stained by hematoxylin. The Bonghan duct in the brain ventricles of rabbits under a stereomicroscope. Image (a) at the bottom of the fourth ventricle beneath the cerebellum of a rabbit did not show any threadlike structures. However, after applying hematoxylin in the same region (b), the Bonghan duct (arrows) emerged near the sulcus. In addition, the Bonghan duct is stained by hematoxylin in the aqueduct and the third ventricle (c) and lifted using a needle to show that it was floating in the cerebrospinal fluid. The inset shows a wound state of the Bonghan duct specimen demonstrating its elastic nature and two Bonghan corpuscles (arrowheads). The scale bar of the inset is 60 μm. Image (d) shows a Bonghan duct (arrows) with a corpuscle (thick arrow) and a node (arrowhead). One end of the structure was cut at the front part of the third ventricle [19]. (D) The Bonghan duct in the central canal of the spinal cord. The Bonghan duct (arrows, a) and its magnified view (b) inside an opened central canal of the spinal cord of a rabbit without dye treatment under a stereomicroscope [19].