All illustrations are taken from Henry Moon's classic 1957 paper.
This is a normal coronary artery. It has been stained to emphasise elastic tissue. Note the continuous folded band of elastin with nothing visible between the elastic layer and the artery lumen (there is actually a single layer of epithelial cells here).
The thicker layer outside the thin black elastic layer is media and is made of muscle. The more granular layer outside the muscle layer is the adventitia. The slide comes from a 5 months gestation human foetus who died, without being born, in a tragic accident. Accidental death autopsies are where all of the pictures in this post come from. Non are cardiac patients.
Next is this picture of the coronary artery of an infant who was 4 days old. Note that most of the intima (dark red wavy layer) is normal and that all of the media is normal. But look at the lower right, there is an abnormal area of the elastic layer. It is shredded and there is fuzziness over the surface. This is the earliest stage of arteriosclerosis noted in this series.
If we next go on to look (slide below) at the coronary arteries from an infant of four months of age we can see a small section of normal intima, with intact elastic layer, on the upper left of the section of artery with normal muscle in the media outside it. Over the rest of the artery the elastic layer is grossly disrupted or absent, the intima is grossly thickened and the muscular media is still relatively normal, though it is a bit thickened at the lower area of the section:
And then we have this superb section actually through a branch of the coronary artery of a child of three years of age. There are some areas of elastic tissue intact but much of it is damaged and the intima has generally thickened wherever the elastic tissue is disrupted. The effect is most marked by the mouth of the branch. The smooth muscle layer (media) is still quite normal but somewhat thickened at the mouth of the branch too.
These last two high magnification images in one picture are stained to show the material of which the thickened intima is composed. In the lower image the changes extend in to the muscular media too.
Do you think it might be cholesterol?
You know, LDL-C, the stick-and-die stuff? Oddly enough if you do frozen sections and stain them with sudan red there are very occasional macrophages with a little lipid in their cytoplasm scattered thinly through this gunk.
But no, the wall to wall stuff stained with Prussian Blue is mucopolysaccharide, I think nowadays it's called glycosaminoglycans or GAG.
To me it's really weird how a cardiologist can think that LDL causes this, and that statins might stop it.
But then the world is a weird place!
Peter
It's Friday and we're heading south for the weekend so the blog will be quiet for a few days.
