Figure 10: NeuN expression in oligodendrocytic nuclei. (a) In the center of the visual field, a large, dark neuronal nucleus (euchromatin) is observed. A small, bright oligodendrocytic nucleus (heterochromatin) is visible below the nucleus of the neuron (arrow). Ten oligodendrocytes can be observed in the section area, in addition to the nucleus marked with an arrow. (b) The same visual field under a green filter. Neuronal nuclei are green. All 10 extraneous oligodendrocytic nuclei are not visible (they do not contain a neuronal marker), but the oligodendrocytic nucleus under the neuron (arrow) remained visible. It is also immunoreactive to NeuN, but much less so compared to the neuron above. ((c), (d)) A later stage heterokaryon’s transformation. In the center of the visible area, a dark, round neuron’s nucleus is located near the light, similarly sized oligodendrocytic nucleus (arrow). The large size of the oligodendrocyte’s nucleus indicates a long reprogramming duration. (c) The expression level of the neuronal marker NeuN in the oligodendrocyte’s nucleus (arrow) does not differ from the neuron’s nucleus. ((a), (c)) Staining with the fluorescent dye DAPI. ((b), (d)) Immunocytochemistry with NeuN labeled with Alexa 488. The scale bar is 10 μm.