title: Perivascular space: possible anatomical substrate for the meridian.
abstract: BACKGROUND
  Despite the meridian system being an important concept in Traditional Chinese Medicine (TCM), modern biology and Western medical systems have failed to find an anatomic substrate. Since the 1960s, a variety of phenomena along meridians have been reported, among which quite a few suggest that along meridians there is a fluid pathway (but not blood vessels or lymphatics). On the other hand, perivascular space (PVS) has been demonstrated to be a body fluid pathway in addition to blood vessels and lymphatics in some mammalian tissues, such as brain, thymus, and lung.
  
  
  OBJECTIVE
  The present study was designed to examine the relationship between PVS and the meridian. We studied characteristics of the tissues around the blood vessels along the Stomach Meridian of Foot-Yangming and the Gallbladder Meridian of Foot-shaoyang, with the goal of identifying anatomical structure corresponding to the meridian described in TCM.
  
  
  RESULTS
  Through perivascular dye injection and frozen section histology, we found that there is PVS around the blood vessels along the meridians, and it is a fluid pathway. Subsequent physiologic studies revealed that the PVS shows significantly greater electrical conductivity and significantly higher partial oxygen pressure (pO(2)) compared to medial and lateral tissues.
  
  
  CONCLUSIONS
  The PVS along the meridians has properties offering good explanation for the meridian phenomena. The work sheds new light on the studies of meridians and may contribute to research on the mechanism of Chinese acupuncture.
authors.affiliation: Department of Analysis-Measurement Science, School of Life Sciences, Wuhan University, Wuhan 430-072, People's Republic of China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Ma
authors.forename: Hua
authors.initials: H
authors.lastname: Tong
authors.forename: Weiya
authors.initials: W
authors.lastname: Xu
authors.forename: Jiming
authors.initials: J
authors.lastname: Hu
authors.forename: Nai
authors.initials: N
authors.lastname: Liu
authors.forename: Hongyi
authors.initials: H
authors.lastname: Li
authors.forename: Lianxin
authors.initials: L
authors.lastname: Cao
mesh_terms: D000818:Animals; D003238:Connective Tissue / Q000033:anatomy & histology; D003287:Contrast Media / Q000008:administration & dosage; D004553:Electric Conductivity; D045604:Extracellular Fluid; D005260:Female; D042601:Lymphatic Vessels / Q000033:anatomy & histology; D008297:Male; D016740:Meridians; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D011817:Rabbits
chemical_list: D003287:Contrast Media