The capillaries in acute and subacute multiple sclerosis plaques: a morphometric analysis.

Two patients, one with multiple sclerosis (MS) and the other with a glioma of the splenium of the corpus callosum, were biopsied with the aid of CAT. Light microscopy, histochemistry, electronmicroscopy and morphometric analysis of counts of mitochondria, dense bodies, and pinocytotic vesicles within the capillary endothelial cells was done. Examination of the MS plaque showed endothelial cell tight junctions to be closed, basal lamina to be thinned, but endothelial cell mitochondria to be the same as in a patient without MS. Pinocytotic vesicles were markedly increased in endothelial cells in MS. Despite intense inflammation in the surround, endothelial lysosomes were as few as in a control.