Novel Anatomic Structures in the Brain and Spinal Cord of Rabbit That May Belong to the Bonghan System of Potential Acupuncture Meridians

Identification of novel threadlike structures in the brain ventricles of rabbits. Stereomicroscopic images at the bottom of the fourth ventricle beneath the cerebellum of the same rabbit before (A) and after (B) hematoxylin application. No threadlike structure is visible in the panel A, but after hematoxylin administration and washing, the threadlike structure (arrows) emerged near the sulcus, as shown in panel B. (C) Stereomicroscopic image of a threadlike structure (arrow) in the aqueduct and the third ventricle of a rabbit brain after hematoxylin was applied and washed. It was lifted by using a needle to show that it was a floating tissue in the cerebrospinal fluid. The inset shows a wound state of the threadlike structure specimen, demonstrating its elastic nature. The overlapped regions show its optical transparency. There are two nodes (arrowheads). The scale bar is 60 μm. (D) Stereomicroscopic image of a threadlike structure (arrow) with a corpuscle (thick arrow) and a node (arrowhead). One end of the structure was cut at the front part of the third ventricle.

Detection of nuclei in a threadlike structure. Phase-contrast microscopic image of a threadlike structure specimen. The three circled bar-like objects coincide with the nuclei shown in (B). Fluorescence microscopic image of the same threadlike structure stained with 4′,6′-diamidino-2-phenylindole. Three nuclei (arrows) are shown.

The visualization of nuclei of the threadlike structure. (A) Combined differential interference contrast and fluorescence microscopic image of a threadlike structure stained with propidium iodide. The nucleus is shown by an arrow. (B) Optically-sectioned images of the same threadlike structure at different depths. These four panels show successive 10 μm in depths from the lower surface of the threadlike structure. The signal increased as the section entered the threadlike structure and then became weaker at the upper surface, which implies that the nucleus was located inside the threadlike structure.

Confocal Laser Scanning Microscopic Image of Yoyo-1 stained threadlike structures. (A) Confocal Laser Scanning Microscopic Image of a threadlike structure (TS) stained by yoyo-1, a DNA-specific dye. Note that there is a clear node-like structure indicated by an arrowhead as shown in Figure 1C. (B) Confocal Laser Scanning Microscopic images of three cross-sectioned threadlike structures after cutting the folded specimen taken in the same site shown in Figure 1. Yoyo-1-stained DNA signal is shown in the center of one of three sectioned specimens.

Threadlike structure surrounded by outer membrane. Confocal Laser Scanning Microscopic image of a threadlike structure stained with Dil, which stains phospholipids and reveals membrane structure. The outer surrounding membrane (arrow) of the threadlike structure is revealed.

The threadlike structure in the central canal of the spinal cord. (A) Threadlike structure (arrow) inside an opened central canal of the spinal cord of a rabbit was lifted by using a needle. (B) The boxed area in the stereomicroscopic image in (A) was magnified to show the transparency of the threadlike structure (arrow). The black and gray horizontal bar is the needle. (C) The threadlike structure had branches (arrowheads) and rod-shaped nuclei (arrows) stained with 4′,6′-diamidino-2-phenylindole. These two features are consistent with those of Bonghan ducts. (D) A magnified view of the threadlike structure around a nucleus (arrow) shown in the panel (C).