Let's pool what we know about CNS capillaries. (CNS meaning central nervous system meaning brain and spine, although I am specifically thinking about the brain.) http://books.google.com/books?id=ElwTtS ... &q&f=false
The endothelial cells are bonded by tight junctions that bar the passage of high molecular weight substances. This is what is generally meant by the blood brain barrier. Unlike capillaries of the general circulation, choroid plexus cells have no intercelluar pores and no fenestrations.
The brain capillary bed is enormous, and has been estimated to cover the area of a tennis court.
Considering the earliest legion of MS is microvascular and considering the ease with which microvessels may be isolated from MS human autopsy brain plaque tissue (Pardridge et al, 1987; Washington et al, 1994), it is somewhat surprising that there are so few studies on the immunology and biochemistry of capillaries isolated from MS plaque tissue.http://www.jneurovirol.com/pdf/5%286%29/556-569.pdf
Somewhat surprising! As if an entire area of possible research, from which possible treatment could arise, had been neglected.
Ok, some interesting things found, but still no clarity on whether or not brain capillaries lack smooth muscle cells. 1eye, I am trying.
Once inside the capillary endothelial cell, the virus may enhance the progression of disease by causing BBB disruption which then facilitates the entry into brain of circulating plasma proteins, which are toxic to astrocytes (Nadal et al, 1995), and circulating immune cells (Soilu-Hanninen et al, 1994).
Similar to a virus disruption, CCSVI disrupts the flow which disrupts the microvasculature in this way. 'Circulating plasma proteins' leak across the BBB and are toxic to astrocytes. Circulating immune cells get across in the same way. But once CCSVI is treated and healthy blood flow is restored, this may heal, and we may in time be well.
Pre-capillary arteriolar smooth muscle cells and capillary pericytes express DR-antigen, indicating antigen presentation in the brain occurs distal to the capillary endothelium.
In the not-as-small-as-a-capillary arterioles, there are smooth muscle cells; but in the capillaries, is it that there are no smooth muscle cells but there are pericytes instead? What is a pericyte?