iC3b staining in substantia nigra specimens. Fig. 1A: Immunoreactive Lewy bodies in a PD substantia nigra specimen; Fig. 1B: Staining of melanized neurons (arrows) in a different PD specimen; Fig. 1C: Immunoreactive neuron with little melanin remaining, same PD specimen as Fig. 1B; Fig. 1D: iC3b staining of melanized neurons (arrows) in a young normal specimen; compare with unstained neurons in lower part of field; Fig. 1E: similar staining pattern in an AD specimen; two prominently stained melanized neurons are seen (arrows) among several unstained neurons; Fig. 1F: iC3b-stained senile plaques in a different AD substantia nigra specimen. (Figs. 1A and 1C, bar = 10 μm; Figs. 1B and 1D–F, bar = 50 μm; immunoreactive structures are dark blue or gray, in contrast to brown melanin and yellow background).