Culture dishes were systematically scanned at 32x and the diameter of each dark neuron measured, along an annotation of its morphology.
For each neuron from which a recording was made, the data was annotated as coming from a clear or dark neuron.
Under bright field illumination, we found dark and clear DRG neurons are distinctly different, with dark neurons composed of four subpopulations, each with unique numbers and distribution of bright rusty-colored cytoplasmic granules, and statistically significant difference in the soma diameter distribution.
However, the membrane properties of the dark neurons showed significant variability (15).
Under bright-field illumination these differences are seen to result from the presence of cytoplasmic granules in the dark neurons, and the absence of granules in the clear neurons.
Based on the granule morphology the dark neurons were divided into subpopulations called: (1) sparse, (2) small loose cluster, (3) large loose cluster, (4) chunky, (5) dense cluster, and (6) clear.
Under bright field illumination, the difference between dark and clear neurons can be seen to result from cytoplasmic granules in the dark neurons, which are absent from the clear neurons.
Recordings from the dark neurons yielded widely different properties, suggesting that the dark neurons are composed of a number of different neuron subpopulations.
Each brain was sectioned coronally in 1-2-mm-thick slices, which all were embedded in paraffin, cut in 5-[micro]m sections, and stained for RNA/DNA with cresyl violet to show dark neurons.
In one control animal we observed a moderate number of dark neurons, but no such change was observed in all the other controls.
Some of these dark neurons were also albumin positive or showed cytoplasmic microvacuoles indicating an active pathologic process.
The number of dark neurons
discovered was significantly and positively associated with the RF EMF dose received by the animals.