Morphological features of a novel tissue, primo-vascular system

Abstract

The primo-vascular system (PVS) is a newly identified vascular network that was first reported in the 1960s by Bong-Han Kim, who claimed that the PVS corresponds to classical acupuncture meridians. The PVS has been observed in various tissues mainly in laboratory animals

however, its detailed structures, functions, and relations to the acupuncture meridians are not yet well understood. In this study, I have investigated the gross morphological and cytological properties of the organ surface PVS (osPVS) and subcutaneous PVS (scPVS) of rat abdomen by staining the PVS with various dyes including Hemacolor, trypan blue, toluidine blue, and acridine orange. The major findings of this study are as follows: (1) osPVS, which consists of primo-node (PN) and primo-vessel (PV), has an inner space ductule (20-50 µm) and a unique cellular composition (90.3%, white blood cells

5.9%, red blood cells

3.8%, mast cells)

(2) scPVS is present in the abdominal subcutaneous tissue, as revealed by Hemacolor staining, and has major characteristics in common with the osPVS in terms of morphology and cellular/structural feature

(3) The distribution and the high density of mast cells in scPVS are closely related with acupuncture meridian and its acupoints (i.e., conception vessel meridian)

(4) the extracellular matrix of os- and scPVS revealed extensive fibers and microparticles (0.5-2 µm) covered with nanoparticles (10-100 nm) in a markedly different manner from those of the lymphatic vessels

(5) osPVS had increased size (2.1-times), number per rat (2.2-times), and ratio of immature red blood cells (2.1-times) in heart failure rats compared to Sham rats, indicating the occurrence of erythropoiesis in the osPVS tissue. Taken together, the results showed the usefulness of Hemacolor staining on the PVS study, the identification of scPVS and its relation with the acupuncture meridians, the ultrastructural properties of os- and scPVS different from lymphatic vessels, and its potential function as a hematopoietic organ of osPVS. These new findings will help to identify various PVS types in the body and further elucidate their pathophysiological roles in healthy and diseased states.