Acupuncture Muscle Channel in the Subcutaneous Layer of Rat Skin

(A) Dorsal skin of a rat. The midline and the transverse line near the lumber sacro point were incised, and the right hand skin was turned over to expose the subcutaneous side into which the staining dye was injected in situ. The dotted lines correspond to the left and the right bladder meridians. Each meridian has two lines. (B) Magnified view of the subcutaneous side corresponding to the boxed area in (A). The two straight lines (arrows) are the acuchannels that were visualized by the flow of chrome-hematoxylin and Dil (1:1 by volume) into the skeletal muscles in the hypodermis. Scale bar, 0.5 mm.

Light microscopic image (A) showing the flow of chrome-hematoxylin and fluorescence light microscopic image (B) displaying the fluorescence from Dil in the acuchannels taken from the visualized straight lines by injection of chrome-hematoxylin and Dil [1:1 (v/v)]. There were two parallel channels in the acupuncture muscle group corresponding to the bladder line. The channels were not uniform in thickness (thick part, Δ; thin part, arrow).

Stereoscopic images of two deep blue colored acuchannels (arrowheads) after injection of Pelikan ink and fluorescent nanoparticles [1:1 (v/v)]. The inset shows a specimen of whole skin around the bladder meridian line. The hair and the epidermis are on the upper side. The anatomical positions of the two acuchannels in the skin are indicated by two arrows and are in the skin skeletal muscle layer just below the hypodermis.

A merged phase contrast and fluorescence light microscope image of a cross-sectioned acuchannel, which was visualized by injection fluorescent nanoparticles (v/v, 1:1). The bright red color is due to the fluorescence of magnetic nanoparticles inside the lumen of an acuchannel. The acuchannel (arrowhead) was a novel kind of muscle fiber and was located among other similar looking muscle fibers (arrows).

Transmission electron microscope images of a rat acuchannel. (A) Low-magnification view of a transverse section of a rat acuchannel (AC) and skeletal muscle fiber (SM). The rectangular area shows the lumen with flowing nanoparticles. (1) – A-band (dark band), (2) – I-band (light band), (3) – Z-line. Magnification × 4000. (B) Magnified image of the rectangular part in Figure 5A showing the distribution of scattered nanoparticles (black dots). The lumen was collapsed. A- and I-bands are denoted by 1 and 2, respectively. Magnification × 25,000. (C) Electron micrograph illustrating a nucleus of rat acuchannel at final stage of mitosis, telophase. At this stage the nucleus was composed of a newly assembled nuclear envelope (1) and decondensing chromosomes (2) with uncoiling chromatin (3). Rat acuchannel is surrounded by a layer of collagen fibers (4). Magnification × 50,000. (D) Highly magnified image of the rat acuchannel showing the I-band with numerous fusiform densities (FD) surrounded by thin filaments. The cytoplasm of acuchannel contains a well developed sacroplasmic reticulum (SR). Magnification × 50,000.