Objective: To investigate material basis of Channel and acupoints.

Methods: (1) Needle retention in vivo for CT Scanning and photograph, and in human corpse for locating its position; (2) Proton impel1ing X-ray ejection (PIXE) onto the interosseous membrane and periosteum of leg specimen; (3) Dissection after red latex vessel perfusion of leg specimen; (4) H.E staining and sectioning transparent treatment and light microscopic observation of the interosseous membrane after Chinese ink vessel perfusion; and (5) Immunohistochemical stain of the anterior tibial artery of rats after loca1 Ca2+ incubation for positive nerve fibers (CGRP,NPY) and light microscopic observation.

Result: (1) The "earth" (middle layer) of acupoints of GB,ST and LU Channels below the neck is closely related to connective tissue structures; (2) Calcium is abundant at the acupoints of the interosseous membrane and periosteum of the leg; (3) The "earth" layer of acupoints on interosseous membrane of leg has direct and indirect segmental periosteum-interosseous membrane branches from both sides of the anterior tibial artery; (4) Vessels (14-84um) in interosseous membrane located superficially and its density are higher in acupoints than these between acupoints. Distribution of the high density of vessels and of rich calcium is identical; (5) Ca2+ of high concentration maybe promote release of CGRP and NPY from the perivascular nerve fibers.

Conclusion: Blood vessels and its perivascular nerve fibers, and calcium in the "earth" layer of the acupoints are possibly the material basis of acupoints.

By Chen Eryu, Dang Ruishan, Cheng Huansheng & Liu Fang