ELECTRON MICROSCOPIC STUDY OF SPINAL CORD OF MICE INFECTED WITH YELLOW FEVER VIRUS.

The ventral horn portion of the lumbar region of the spinal cord of mice infected with yellow fever virs was studied with the electron microscope. The virus was identified in the cytoplasm of the motor neurons and in microglia. In the neurons, the virus was observed free in the cytoplasmic matrix, within the cisterns of the endoplasmic reticulum, and in close association with “Golgi-like organelles.” These organelles, which appeared to be specific to the presence of the virus, consisted of an osmiophilic core showing a crystalloid configuration and emitting thin filaments which connected to a system of numerous vesicles. Other alterations included dilation of the endoplasmic reticulum, clearing of the cytoplasm, and swelling of mitochondria. The virus particles were also found free in the cytoplasmic matrix of the microglia, inside their characteristic vacuoles, and in relation to “Golgi-like organelles” such as described. No alterations or particles were observed in the astrocytes or endothelial cells. These findings are compared with those previously described in the brain.