Visualization of the network of primo vessels and primo nodes above the pia mater of the brain and spine of rats by using Alcian blue.

By spraying and injecting Alcian blue into the lateral ventricle, we were able to visualize the network of the nerve primo vascular system above the pia mater of the brain and spine of rats. Staining these novel structures above the pia mater with 4',6-diamidino-2-phenylindole demonstrated that they coexisted in cellular and extracellular DNA forms. The cellular primo node consisted of many cells surrounded by rod-shaped nuclei while the extracellular primo node had a different morphology from that of a general cell in terms of DNA signals, showing granular DNA in a threadlike network of extracellular DNA. Also, differently from F-actin in general cells, the F-actin in the primo vessel was short and rod-shaped. Light and transmission electron microscopic images of the PN showed that the nerve primo vascular system above the pia mater of the brain and spine was a novel dynamic network, suggesting the coexistence of DNA and extracellular DNA. Based on these data, we suggest that a novel dynamic system with a certain function exists above the pia mater of the central nerve system. We also discuss the potential of this novel network system in the brain and spine as related to acupuncture meridians and neural regeneration.