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Table 1 Types of blood vessels in various organs with different permeability

From: Regulation of blood vascular permeability in the skin

A. Charge barrier [17,18,19,20,21,22,23]
Glycocalyx layer Anionic mesh-like layer with regular spacing of <20 nm for continuous and fenestrated vessels (irregularly found on sinusoidal vessels), on both the surface of IEJ clefts and endothelial cells.
B. Size barrier (reviewed in [2])
Types of blood vessels Types of endothelial cells Interendothelial junctions (IEJs) Representative organs Estimated upper limit for paracellular transportation [4]
Continuous(non-fenestrated) Continuous basement membrane No fenestrae Tight junctions and adherens junctions Retina [2] brain, spinal cord [66] thymus [67] Determined by IEJs (TJs) <1 nm
Adherens junctions with limited contribution of tight junctions skin [12, 13] muscle, heart [68, 69] adipose tissue [70] lung [71, 72] Determined by IEJs (AJs) <5 nm
Fenestrated Fenestrated (with diaphragm) skin [12, 13] exocrine glands [73] kidney (peritubular) [74] endocrine glands [73, 75, 76] intestinal mucosa [77, 78] lymph node [79, 80] Determined by diaphragm <6–12 nm [81]
Fenestrated (open pores without diaphragm) Kidney (glomerulus) [82, 83] Determined by glycocalyx <15 nm [2, 19]
Sinusoidal (discontinuous) Discontinuous basement membrane Fenestrated (with and/or without diaphragm) Liver [84,85,86] spleen [87] <50–280 nm, largely differ among species <3–5 μm