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Evidence-Based Complementary and Alternative Medicine
Volume 2015, Article ID 751937, 13 pages
Research Article

Identification of Primo-Vascular System in Abdominal Subcutaneous Tissue Layer of Rats

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151-742, Republic of Korea

Received 3 October 2014; Revised 22 December 2014; Accepted 26 December 2014

Academic Editor: Kwang-Sup Soh

Copyright © 2015 Chae Jeong Lim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The primo-vascular system (PVS) is a novel network identified in various animal tissues. However, the PVS in subcutaneous tissue has not been well identified. Here, we examined the putative PVS on the surface of abdominal subcutaneous tissue in rats. Hemacolor staining revealed dark blue threadlike structures consisting of nodes and vessels, which were frequently observed bundled with blood vessels. The structure was filled with various immune cells including mast cells and WBCs. In the structure, there were inner spaces (20–60 µm) with low cellularity. Electron microscopy revealed a bundle structure and typical cytology common with the well-established organ surface PVS, which were different from those of the lymphatic vessel. Among several subcutaneous (sc) PVS tissues identified on the rat abdominal space, the most outstanding was the scPVS aligned along the ventral midline. The distribution pattern of nodes and vessels in the scPVS closely resembled that of the conception vessel meridian and its acupoints. In conclusion, our results newly revealed that the PVS is present in the abdominal subcutaneous tissue layer and indicate that the scPVS tissues are closely correlated with acupuncture meridians. Our findings will help to characterize the PVS in the other superficial tissues and its physiological roles.