Figure 8: Changes in the structure of the chromatin and the size of the oligodendrocytic nucleus after fusion with a neuron. (a) The oligodendrocytic nucleus is indicated with an arrow. It is located in the neuron’s cytoplasm. The nucleus has not changed yet; it is still small, and the chromatin structure cannot be revealed. (b) Beginning of the reprogramming. The size of the nucleus (arrow) did not change, but the chromatin divided into dark heterochromatin and pale euchromatin in the center of the nucleus. (c) The oligodendrocyte’s nucleus (arrow) size increased significantly. The heterochromatin belt along the nuclear membrane is wider than that of the neuron’s nucleus. (d) Reprogramming completion. The heterokaryon has completely been transformed into a cell that has two identical nuclei—a dikaryon. Semi-thin sections. The scale bar is 10 μm.