Visualizing the Network of Bonghan Ducts in the Omentum and Peritoneum by Using Trypan Blue

Comparison of a Bonghan duct (BHD) before and after Trypan blue visualization. (A) Adipose tissue around the small intestine. A Bonghan corpuscle (BHC, arrow) was detected, but its BHD was barely observable. (B) After staining with Trypan blue, the BHD (thick arrow) on the adipose tissue was clearly visualized. Blood vessels and adipose tissues were not stained.

Weblike network of BHDs revealed by using Trypan blue. (A) The web of BHDs on the visceral peritoneum around the stomach near the spleen of a rat. There were several small BHCs at crossing points, as indicated by the arrows. The blood capillaries were not stained. (B) The network of BHDs on the omentum below the stomach and over the small intestine. Three small corpuscles at the crossing points of BHDs are indicated by the arrows. (C) In the inset another part of the same omentum as in (A) is shown. Here, the floating BHD (open arrow) was connected to the BHDs (arrows) in the omentum. This figure shows that BHDs on the omentum was a part of the larger network of freely movable BHDs on the surfaces of internal organs which were previously reported [].

A phase-contrast image of a BHD merged with an image of nuclei stained by using DAPI (blue color). The figure shows the characteristic features of a BHD, rod-shaped nuclei, and a bundle structure, which provide simple criteria to identify a BHD from among similar looking structures. Some of the rod-shaped nuclei are indicated by arrows.