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

Figure 4

The structure of the Bonghan duct and corpuscle. (A) The structure of a Bonghan duct determined by the Bonghan research team. Diagram and photos showing the structure of the Bonghan duct and corpuscle. The Bonghan duct (a) consists of several subducts (Bonghan ductules) and three layers, and each layer has peculiar nuclei. Under a phase-contrast microscope, subducts and rod-shaped nuclei of endothelial cells (b) are observed. An electron micrograph of the internal BD (c) through a cross section (×42,000). BL = Bonghan liquor; BD = Bonghan ductule; IS = interstitial substance; WBD = wall of Bonghan ductule; ENBD = endothelial nucleus of Bonghan ductule; CEC = cytoplasm of endothelial cell. Photo image showing the rod-shaped nuclei of endothelial cells (d) from the intraexternal Bonghan duct stained using Feulgen reaction under a stereomicroscope (×400). Photo image (e) of the internal Bonghan duct and corpuscle (×63) [5]. (B) The Bonghan duct and corpuscle stained using acridine orange. The Bonghan duct (PV) and corpuscle (PV, dotted circle) inside the bovine heart stained by acridine orange under a confocal laser scanning microscope. The rod-shaped nuclei (arrows) are aligned longitudinally to the bundle of the Bonghan duct. Round nuclei (arrowheads, e) also exist. All scale bars are 20 μm [20]. (C) The structure of the Bonghan duct. Histological observation of the Bonghan duct, whole specimen and cross-sectioned. Photomicrograph (a) of merged phase-contrast and fluorescent image of a Bonghan duct, which shows the bundle of several ductules (arrows) with characteristic rod-shaped nuclei stained with DAPI (bright blue) and immune cells (arrowheads) on duct surface. The scale bar is 50 μm. Cross-sectioned Bonghan duct (b) also presents several ductules (arrows). The scale bar is 10 μm [22].