During a last decade, there have been considerable reports of novel thread-like structures (NTSs) in animals. The NTSs are thought to be a part of the Bonghan Ducts (BHD) system, which is described as a newly-discovered circulatory system. Networks of BHD system are completely different from blood vessels or lymphatic system in animal. To demonstrate intravascular NTSs, it is necessary to develop the effective method to observe the NTSs morphology. We considered several methods to study morphologically with NTSs. There are not explaining such structure in the current knowledge of anatomy and physiology. But we found very effective and easy method to study NTSs and BHD by agar-mediated embedding method.