Visualization of Acupuncture Meridians in the Hypodermis of Rat Using Trypan Blue

(A) Light microscopic image of a meridian primo-vessel (superficial Bonghan duct) reported by Bonghan Kim [1]. (B) Magnified view of (A). The slits indicated by arrows are a noticeable feature. A primo-vessel is composed of many channels like a vascular bundle. This original picture had no information on the scale bar and staining name.

Stereoscopic images of skin that is (A) without staining, (B) with Trypan blue (TB)-staining and (C) magnified view of (B). TB-stained subcutaneous skin (B) reveals a blue-colored threadlike structure, part of which is magnified in (C). Notice that the skin skeletal muscle (SSM) just near the blue line was not stained by TB. H = hypodermis; D = dermis.

A piece of skin tissue in Figure 2 taken and observed with a light microscope. (A) Microscopic image of a Trypan blue-stained structure (TBS) and nearby skin skeletal muscle (SSM) unstained by Trypan blue. The TBS has noticeable slits, which are indicated by arrows. (B) The dotted rectangle in (A) is magnified. Nuclei are shown blue by DAPI. The SSM has distinctive striated lines on its surfaces whereas the TBS does not. The slit in the TBS is indicated by an arrow. Also, a noticeable difference between the circle (tip of the TBS) and the dotted circle (tip of the skin skeletal muscle) is apparent. After simultaneous cutting of the TBS and the SSM had occurred, the tip of the TBS (the lined circle) was a little shrunken and slightly rounded in shape, but the tip of the SSM (the dotted circle) was cut sharply.

Hematoxylin and eosin staining of the cross sections of skin skeletal muscle (SSM) and Trypan blue-stained structures (TBS). (A) Cross section of skin containing the SSM and the TBS. (B) Magnified view of the TBS from the dotted rectangle of Figure 4A in which there are small sinuses (dotted arrows) and large sinuses (solid arrows).