It is often necessary to confirm the precise path followed by electrodes needles that have been inserted into the brain. NSA performs two stains that illustrate electrode tract paths.

In the images below, the electrode needles were inserted to create a lesion in select amygdala nuclei. The animal was sacrificed one year later and evidence of the tract insertion is still present and can be seen in two ways. The penetration nicks small blood vessels and the iron in the red blood cells remains in the tissue. The iron is revealed using the Perls reaction for ferric iron and then enhanced with diamino benzidine (DAB). Other areas stained reddish brown, the globus pallidus are naturally rich in iron. Another way to see the evidence by the presence of reactive astrocytes, which are visualized with antibody staining for a protein unique to astrocytes, GFAP (glial fibrillic acid protein). The long persistence of reactivity of the astrocytes might be due to the presence of the iron.

Above: GFAP stain indicating electrode needle tract

Above: Perls/DAB stain indicating electrode needle tract

 

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