The pathway followed by macromolecules across the wall of visceral capillaries has been studied by using a set of tracers of graded sizes, ranging in diameter from 100 A (ferritin) to 300 A (glycogen). Polysaccharide particles, i.e. dextran 75 (mol wt approximately 75,000; diam approximately 125 A), dextran 250 (mol wt 250,000; diam approximately 225 A), shellfish glycogen (diam approximately 2...

The number of perfused capillaries in skeletal muscle varies with muscle activation. With increasing activation, muscle fibers are recruited as motor units consisting of widely dispersed fibers, whereas capillaries are recruited as groups called microvascular units (MVUs) that supply several adjacent fibers. In this study, a theoretical model was used to examine the consequences of this spatial...

A new velocimeter for measurements in microscopic regions is presented. A common charge coupled device (CCD) has been used as spatial filter for one-component velocity measurements. The characteristics of this sensor are investigated and first application results presented.

A major obstacle toward creating human-scale artificial tissue models is supplying encapsulated cells with oxygen and other nutrients throughout the construct. In particular, channels in hydrogels that match resolution density of smallest blood capillaries (≤10 µm) remains highly challenging. Here, a novel method demonstrated where polycaprolactone fibers printed using melt-electrowriting are c...

Adaptive Optics Scanning Laser Ophthalmoscopy was used to noninvasively acquire videos of single-file flow through live human retinal parafoveal capillaries. Videos were analyzed offline to investigate capillary flow dynamics. Certain capillaries accounted for a clear majority of leukocyte traffic (Leukocyte-Preferred-Paths, LPPs), while other capillaries primarily featured plasma gap flow (Pla...

The hyaloid vessels form a capillary network on the inner surface of the retina. These capillaries are embedded in the vitreous humor, and they lack a glial investment. The intercellular spaces of the retina communicate with the ocular cavity, as can be evidenced by following the penetration of tracer substances. Hence, there is an extracellular diffusion pathway between hyaloid capillaries and...

In this work, we present observations about the transport of 15.2 keV electrons with a beam current 21 μA through macroscopic dielectric capillaries. These capillaries are made borosilicate glass an inner diameter 6 mm, and samples bending angle 90° 360° were investigated. The electron gun was adjusted, injected into capillary had divergence half 0.75°. A retarding field analyzer (RFA) installe...

The literature dealing with the permeability of blood capillaries is voluminous. Nothing appears to have been published, however, concerning the permeability of blood capillary sprouts and newly formed blood capillaries as compared to that of older capillaries. Yet this would seem to be a matter of some importance, since there now appears to be a general agreement (1) that the growth of the ent...

The ultrastructural features that are critical to the efficient functioning of the blood-brain barrier (b-bb) were quantified in typical barrier vessels, i.e., cerebral gray and white matter capillaries, and compared with the same parameters in cerebral nonbarrier capillaries (area postrema), and in somatic capillaries, (muscle) of the mouse. The image analysis was done with the help of a simpl...

The mechanism of cancer cell deformation and migration in narrow vessels is incompletely understood. In order to visualize the cytoplasmic and nuclear dynamics of cells migrating in capillaries, red fluorescent protein was expressed in the cytoplasm, and green fluorescent protein, linked to histone H2B, was expressed in the nucleus of cancer cells. Immediately after the cells were injected in t...