Primo vascular system floating in lymph ducts of rats

Primo Vessels Inside Lymphatic Vessels Are Absent in an ALS Mouse Model

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the selective death of motor neurons in the central nervous system. It is also a representative rare disease among degenerative diseases of the nervous system. Although many drugs for the treatment of degenerative brain diseases are being developed, they are not delivered correctly to the target due to the blood-brain barrier. The present study aimed to analyze changes in the primo vascular system (PVS) in ALS mice with symptoms and the partial oxygen pressure (pO2) in normal mice. In normal mice, we consistently observed primo vessels in lymphatic vessels (L-PVS). However, in ALS mice with symptoms, L-PVS were mostly lost, rendering them difficult to observe. The pO2 of the L-PVS in normal mice was significantly higher than that of normal dermis and lymph nodes.In conclusion, the relatively higher oxygen levels measured in the L-PVS than in normal dermis and lymph nodes suggest a role for the PVS in oxygen transport and enable a hypothesis that the L-PVS can function as a drug delivery pathway.

Tissue Concentration Analysis of Sulfur, Calcium and Oxygen in Novel Skin Primo Nodes After Acupuncture

Over the past 5000 years, acupuncture has been practiced in Korea, China, and Japan to relieve various diseases, and it is now widely used and accepted worldwide. Although the anatomical substance and function of meridians has been actively studied, it is still not clearly defined. One of the keys to acupuncture is determining the specific anatomical location exactly on or under the skin. We discovered that the skin primo node is a new anatomical structure in the skin of rats. The present study aimed to analyze the relationship between skin primo nodes and acupoints through changes in the expression of tissue concentrations of skin primo nodes. Analysis of this skin primo node confirmed that the skin primo node after acupuncture had a significantly higher concentration of sulfur and calcium than found in normal skin. And the significant pO2 in the skin primo node was confirmed by measuring pO2 using a needle oxygen sensor. Through sulfur, calcium, and pO2 concentration values of skin primo nodes, we confirmed whether these nodes could be related to acupoint. To understand the clear structure and function of this node, it is necessary to further study through the known properties of acupoints and the function of Primo Vascular System (PVS).

Monitoring the primo vascular system in lymphatic vessels by using window chambers

This study aims to develop a window chamber system in the skin of rats and to monitor the primo vascular system (PVS) inside the lymphatic vessels along the superficial epigastric vessels. The PVS in lymphatic vessels has been observed through many experiments under in vivo conditions, but monitoring the in vivo PVS in situ inside lymphatic vessels for a long time is difficult. To overcome the obstacles, we adapted the window chamber system for monitoring the PVS and Alcian blue (AB) staining dye solution for the contrast agent. The lymphatic vessels in the skin on the lateral side of the body, connecting the inguinal lymph nodes to the axillary lymph nodes, were the targets for setting the window system. After AB had been injected into the inguinal lymph nodes with a glass capillary, the morphological changes of the stained PVS were monitored through the window system for up to twenty hours, and the changes in the AB intensity in the PVS were quantified by using image processing. The results and histological images are presented in this study.

Exploration of differentiation standard for primo through the histological common point of threadlike structure found in rats and swine

BACKGROUND

The novel threadlike structure is called the primo structure, and studies are conducted through many different approaches. Although various ways of differentiation are currently used, a standard for differentiation is deemed necessary in order to identify the primo structure based on the overall form of the structure. This study aims to explore the differentiation standard through the histological common point of the threadlike structure of rat and swine by using the hematoxylin and eosin (H&E) staining method commonly used for histological research in various structures.

METHODS

An 8-week old Sprague-Dawley rat and a Yorkshire pig weighing 30-40 kg were used. A total of 65 pieces of rat threadlike structure and 100 pieces of swine threadlike structure were collected after the abdomen was cut and opened. The following three different characteristics were confirmed using the H&E staining method for the collected structures: (1) bright cell availability; (2) cavity availability; and (3) nuclei density.

RESULTS

For the rat threadlike structure, the bright cell (70.5%) and nuclei density (92.6%) were mainly observed; in the swine threadlike structure, however, the bright cell (60.6%) and cavity (67.2%) were mainly observed. The bright cell was confirmed to have been observed in the threadlike structures of both rat and swine.

CONCLUSION

The bright cell is determined to be the common point in the primo structure. However, further research is deemed necessary in the future as to the functions performed by the characteristic shown by the Primo structure.

Protocol for Detecting the Primo Vascular System in the Lymph Ducts of Mice

The primo vascular system (PVS), which is the proposed conduit for the acupuncture Qi, is a complex network distributed throughout an animal's body. However, even with a microscope, it is not easily detectable because of its transparency. Thus, its existence is largely unknown in current anatomy. A convincing demonstration of its existence is needed. The lymph-primo vessel (PV), which is a subsystem of the PVS, is a very effective visual demonstration of the PVS. The lymph-PVS is a mobile threadlike structure floating in lymph ducts that has been observed in rabbits, rats, and mice by several independent teams. The involved techniques are novel and rather complicated; therefore, we have already provided detailed protocols for the surgery; for the injection of the staining dye; and for the detection, extraction, and identification of the PVS in rabbits and rats. However, the mouse is one of the most important laboratory animals used for various biomedical research purposes. For the convenience of researchers who wish to initiate the PVS experiments in mice, we provide a shortened version of the protocol, despite many similarities with previously published protocols. Thus, researcher can easily obtain the samples of the lymph-PVS of mice.

A Novel Technique for Visualizing the Intralymphatic Primo Vascular System by Using Hollow Gold Nanospheres

Until recently, the primo vascular system (PVS) has been unnoticed by most anatomists due to the small diameter and translucent features of the threadlike network. These properties make primo vessels (PVs) difficult to visualize for harvest and for further characterization. One particular PVS subtype that is located within the lymphatic vessels (LVs) is of strong interest because with a proper contrast, these long PVs can be visualized through the transparent LV wall and can be harvested to provide sufficient sample material for analysis. The most common method to visualize this PVS subtype utilizes Alcian blue as the contrast agent. This technique is effective, but tedious, and has relatively low repeatability. The purpose of this study was to develop a new technique that allows reliable visualization of the intralymphatic PVS (IL-PVS) in a user-friendly manner. The method was designed to provide optical contrast to the PVS by taking advantage of the porous nature of the PV's external wall and interstitial matrix. Turquoise-green-colored hollow gold nanospheres (HGNs) in the size range of 50-125 nm were found to provide excellent optical contrast for the IL-PVS in rats. The PVS was visualized within 10 minutes after HGN administration at a 95% success rate.

Temporal Change of Alcian Blue-Stained Primo Vascular System in Lymph Vessels of Rats

This study aims to investigate the temporal change of a vascular system now known as the primo vascular system (PVS). We used Alcian blue (AB) dye for imaging the distribution of the PVS in lymphatic vessels. The target lymph vessels were chosen as they are easily accessible from the skin, and long-term observation is possible with intact physiological conditions due to a minimal surgical procedure. AB solution was injected into the inguinal lymph node and the target lymph vessels were located along the superficial epigastric vessels. The imaging system allowed processing for extraction of images showing changes in the AB intensity of the visualized PVS components. This newly developed procedure can be used for further study on various dynamic processes of PVS in lymph vessels.

A Hyaluronic Acid-Rich Node and Duct System in Which Pluripotent Adult Stem Cells Circulate

Regenerative medicine is in demand of adult pluripotent stem cells (PSCs). The "Bonghan System (BHS)" was discovered and suggested to contain cells with regenerative capacity in the early 1960s. It had been ignored for a long time due to the lack of sufficient details of experiments, but about 37 years after the initial report, the BHS was rediscovered and named as the "primo vascular system." Recently, we have discovered a similar structure, which contained a high level of hyaluronic acid, and hence, named the structure as hyaluronic acid-rich node and duct system (HAR-NDS). Here we discuss the HAR-NDS concept starting from the discovery of BHS, and findings pointing to its importance in regenerative medicine. This HAR-NDS contained adult PSCs, called node and duct stem cells (NDSCs), which appeared to circulate in it. We describe the evidence that NDSCs can differentiate into hemangioblasts that further produced differentiated blood cells. The NDSCs had a potential to differentiate into neuronal cells and hepatocytes; thus, NDSCs had a capability to become cells from all three germ layers. This system appears to be a promising alternative source of adult stem cells that can be easily delivered to their target tissues and participate in tissue regeneration.

Identification of Primo-Vascular System in Abdominal Subcutaneous Tissue Layer of Rats

The primo-vascular system (PVS) is a novel network identified in various animal tissues. However, the PVS in subcutaneous tissue has not been well identified. Here, we examined the putative PVS on the surface of abdominal subcutaneous tissue in rats. Hemacolor staining revealed dark blue threadlike structures consisting of nodes and vessels, which were frequently observed bundled with blood vessels. The structure was filled with various immune cells including mast cells and WBCs. In the structure, there were inner spaces (20–60 µm) with low cellularity. Electron microscopy revealed a bundle structure and typical cytology common with the well-established organ surface PVS, which were different from those of the lymphatic vessel. Among several subcutaneous (sc) PVS tissues identified on the rat abdominal space, the most outstanding was the scPVS aligned along the ventral midline. The distribution pattern of nodes and vessels in the scPVS closely resembled that of the conception vessel meridian and its acupoints. In conclusion, our results newly revealed that the PVS is present in the abdominal subcutaneous tissue layer and indicate that the scPVS tissues are closely correlated with acupuncture meridians. Our findings will help to characterize the PVS in the other superficial tissues and its physiological roles.

Comparison of Alcian Blue, Trypan Blue, and Toluidine Blue for Visualization of the Primo Vascular System Floating in Lymph Ducts

The primo vascular system (PVS), floating in lymph ducts, was too transparent to be observed by using a stereomicroscope. It was only detectable with the aid of staining dyes, for instance, Alcian blue, which was injected into the lymph nodes. Some dyes were absorbed preferentially by the PVS than the lymph wall. It remains a standing problem to know what dyes are absorbed better by the PVS than the lymph walls. Such information would be useful to unravel the biochemical properties of the PVS that are badly in need for obtaining large amount of PVS specimens. In the current work we tried two other familiar dyes which were used in PVS research before. We found that Trypan blue and toluidine blue did not visualize the PVS. Trypan blue was cleared by the natural washing. Toluidine blue did not stain the PVS, but it did leave stained spots in the lymph wall and its surrounding tissues, and it leaked out of the lymph wall to stain surrounding connective tissues. These completely different behaviors of the three dyes were found for the first time in the current work and provide valuable information to elucidate the mechanism through which some special dyes stained the PVS preferentially compared to the lymphatic wall.