Observation of coiled blood plexus in rat skin with diffusive light illumination.

Blood plexuses are characteristic anatomical features of acupuncture points (APs). We developed an optical technique using diffusive light illumination to increase the brightened area of skin for observation of the blood plexuses in skin. We found that the blood plexuses were coiled blood vessels which came out of the perforations in the fascia of muscle. The coiled vessels could be straightened by stretching the skin. We observed a series of blood plexuses at the putative APs along the left and right kidney meridian lines in the abdominal skin of rats. In addition, the locations of the plexuses on the muscle fascia were just above the putative acupuncture muscle channels along the kidney meridians. Furthermore, immunohistochemical analysis of the skin specimens of the plexuses revealed its neurovascular bundle nature as expected from known anatomical features of the APs.