Background: Astrocytes within the hypothalamic arcuate nucleus contain Gomori-positive inclusions that exhibit a nonenzymatic peroxidase activity. The source and composition of these Gomori-positive inclusions are currently unknown. Recent evidence, derived from cultured astrocytes, suggests that Gomori-positive inclusions may consist of autophagocytized accumulations of altered mitochondria and that the peroxidase activity is generated by iron or other metals which accumulate in these mitochondria.

Methods: The present study applies electron microscopy, energy dispersive X-ray microanalysis, and immunocytochemistry in conjunction with confocal microscopy to determine the structure and composition of Gomori-positive inclusions in vivo.

Results: The results indicate that Gomori-positive inclusions are heterogeneous structures often associated with microtubules and that they contain conspicuous mitochondrial components. Gomori-positive inclusions exhibit X-ray emission peaks for copper and, less often, chromium, either of which could account for the peroxidase activity.

Conclusions: These results support the hypothesis that Gomori-positive inclusions are autophagosomes in which mitochondria are prominent.