Figure 3.

Double-labeling of brain sections detects cells coexpressing the microglial marker F4/80 and the neo^R retroviral tag. The F4/80 monocyte/macrophage antigen was detected by indirect immunofluorescent antibody labeling; ³⁵S-radiolabeled probes were used to hybridize to neo^R mRNA. The photomicrograph is of a representative field from an animal sacrificed 35 days after bone marrow transplantation. A cell in the center stains positive for the F4/80 antigen (red) and exhibits labeling with radioactive probe to neo^R transcripts. The dark field image was photographed using a green filter so that autoradiographic grains would appear green (yellow where they overlap red immunostaining). (Bar = 10 μm.)