  In the development of oligodendrocytes in the central nervous systems, the
inner and outer tongue of the myelin sheath tend to be located within the same
quadrant, which was named as Peters quadrant mystery. In this study, we conduct
in silico investigations to explore the possible mechanisms underlying the
Peters quadrant mystery. A biophysically detailed model of oligodendrocytes was
used to simulate the effect of the actional potential-induced electric field
across the myelin sheath. Our simulation suggests that the paranodal channel
connecting the inner and outer tongue forms a low impedance route, inducing two
high-current zones at the area around the inner and outer tongue. When the
inner tongue and outer tongue are located within the same quadrant, the
interaction of these two high-current-zones will induce a maximum amplitude and
a polarity reverse of the voltage upon the inner tongue, resulting in the same
quadrant phenomenon. This model indicates that the growth of myelin follows a
simple principle: an external negative or positive E-field can promote or
inhibit the growth of the inner tongue, respectively.
