When blood remains static, erythrocytes and plasma tend to aggregate, forming a static fibrous network gel structure. When flowing, erythrocytes and plasma can act as a mobile fibrous network complex that is dispersed in blood. Plasma and mature erythrocytes can be viewed as a special type of interstitium in blood. Mature erythrocytes do not contain a nucleus and are rich in proteins. Blood is a type of general connective tissue made up mostly of erythrocytes. This system is the interstitial structure, and the liquid in the interstitial structure is termed interstitial fluid. Collagen, elastin, and mucopolysaccharides connect to form a non-liquid system consisting of a fibrous network filled with hydrophilic, porous media. The interstitium, which is present between parenchyma, is ubiquitous in complex living things. 2 Interstitial Structure and Interstitial Fluid 2.1 Definition of Interstitial Structure and Interstitial Fluid Hence, multiscale fluid behavior in interstitial structures is key for examining and understanding behavioral activities in living things. The substance transports of the interstitial stream, including material transfer, energy transduction, and information transmission, probably serve to enable flat connections between functional structures in living things and form a horizontal bridge between various parts of a living thing to integrate function and behavior. to outline this horizontal fluid connection pathway based on the interstitial structure between various organs and tissues. The concept of interstitial stream was proposed by Han et al. Various levels of interstitial structure, which are distributed between tissues, constitute a path for fluid connections between these tissues. There is reason to believe that different fluid connections are present at all scales between millimeters and nanometers. In the circulatory system, the heart pumps blood to various organs and tissues in the human body, constituting vertical connections between organs and tissues. These fluids comprise vertical connections in various parts of a living thing. In biological systems, an orderly fluid flow is present in blood vessels and the urinary tract at the millimeter scale and in proton channels at the nanometer scale. Among these types of matter, multiphasic fluids in living things show an orderly multiscale spatial flow that determines biological activities. From the material perspective, living things can be described as being composed of soft matter, such as intracellular stress fibers filled with intracellular fluid at the molecule level, a fibrous network filled with tissue gel in the extracellular matrix at the cellular level, capillaries at the tissue level, multi-tissue organs and multiphasic media in these tissues at the organ level, and cavities and tissues at the organism level. Complex living things show a hierarchical organization from molecules, cells, tissues, organs, and systems to an organism. De Gennes, proposed the concept of soft matter and started promoting the interdisciplinary development of a subject that encompasses physics, chemistry, and biology. In 1991, the Nobel laureate and French physicist, P. This will provide a foundation for the development of medicine of soft matter. By starting from the perspective of soft matter, a new understanding can be gained of health and disease and quantitative physical markers for research, clinical diagnosis, and treatment can be provided, as well as prognosis evaluation in complex diseases such as cancer and Alzheimer's disease. Interstitial stream transport can be used as a basis to fully mine hierarchal behavior in images to expand imaging behavior into an omics field. In this review, recent advances in physical and chemical properties, the substance transport model, and the characterization methods of interstitial streams at the mesoscopic scale, as well as the relationships between interstitial streams and disease are summarized. Accordingly, the evaluation of interstitial stream transport behavior at the mesoscopic scale is essential. The substance transport of interstitial streams follows mesoscopic fluid behavior dynamics, which is intimately associated with material transfer in nanoconfined spaces and a unique signal transmission. The recent discovery of the efficient transport mechanisms of interstitial streams has provided a new understanding of these complex activities.
Living things comprise a typical hierarchical and porous medium, and their most fundamental logical architectures are interstitial structures encapsulating parenchymal structures.