An extravascular fluid transport system based on structural framework of fibrous connective tissues in human body

Abstract

Objective: Interstitial fluid in extracellular matrices may not be totally fixed but partially flow through long-distance oriented fibrous connective tissues via physical mechanisms. We hypothesized there is a long-distance interstitial fluid transport network beyond vascular circulations. Materials and methods:We first used 20 volunteers to determine hypodermic entrant points to visualize long-distance extravascular pathway by MRI. We then investigated the extravascular pathways initiating from the point of thumb in cadavers by chest compressor. The distributions and structures of long-distance pathways from extremity ending to associated visceral structures were identified.Results: Using fluorescent tracer, the pathways from right thumb to right atrium wall near chest were visualized in seven of 10 subjects. The cutaneous pathways were found in dermic, hypodermic and fascial tissues of hand and forearm. The perivascular pathways were along the veins of arm, axillary sheath, superior vena cava and into the superficial tissues on right atrium. Histological and micro-CT data showed these pathways were neither blood nor lymphatic vessels but long-distance oriented fibrous matrices, which contained the longitudinally assembled micro-scale fibres consistently from thumb to superficial tissues on right atrium.

Active interfacial dynamic transport of fluid in a network of fibrous connective tissues throughout the whole body

“…To further confirm the universal existence of the above discoveries in the whole body, the human cadavers were used to testify the extravascular pathways by the simulated heart pulsation using a mechanical chest compressor. 14 The perivascular pathways from the thumb were observed along the veins of the arm, axillary sheath, superior vena cava and in the superficial tissues on the right atrium. Histological and micro-CT (a higher resolution) data showed that these long-distance pathways were neither blood nor lymphatic vessels but the fibrous connective tissues, in which the micron-sized fibres were longitudinally assembled from the thumb to the superficial tissues on the right atrium and appendage.…”

“…15 The ITZ is not an interface of a few molecular layers but contains a thin, probably a nanometre-thickness space paved on a solid surface. 14…”

“…One of the driving sources in an IDT system has been proposed to be the dynamic to and fro "gel pump." 14 The detailed kinetic and dynamic mechanisms to modulate fluid in an IDT system are waiting-to-be-explored in an alive biological system and especially humans. (g) Beyond cardiovascular circulation, a F I G U R E 2 A diagram of an adventitial ISF/IDT system that illustrates a part of the hypothesized interstitial fluid circulatory system.…”

“…The pore sizes or compartment sizes of the ITZs might be variable in physiological or pathophysiological conditions, which may be a nano‐scale space paved on a fibre or even a micron‐scale space paved on a layer of cells. Both of an ITZ and its contacting gel play as a basic unit of kinetic and dynamic transport processes for fluid flow . Indeed, the detailed microscopic structures of the ITZ and the interactions between the ITZ and the gel matrix need further studies.…”

Integrating complementary medicine in the perioperative period: a simple, opioid-sparing addition to your multimodal analgesia strategy?

“…For example, in acupuncture, functional magnetic resonance imaging studies are increasingly being conducted to delineate areas of brain activation with needle placement and have revealed several differences between true and sham acupuncture 42. Investigations using cadavers and animal models have also helped explain how distal acupoints may modulate pain responses 43 44. Despite this increasing evidence, concerns that acupuncture may simply be a placebo continue to dominate the conversation 45…”