Figure 3

Schematic diagram of competing tSCs, vacancies, and axons. (a) An endplate covered with four different types of axon terminals (light blue, purple, cyan, and dark blue) and a tSC (green) transitions into an endplate covered with three of the axon terminals after removal of one axon terminal from the four and a vacancy (black) that takes the  place of the removed axon. (b) Competition of tSCs, vacancies, and axons. A blue circle represents a synaptic site formed on a muscle fiber by an axon. A green circle represents a synaptic site formed on a muscle fiber by a terminal Schwann cell (tSC). A black circle represents a vacancy having no axon or tSC on a muscle fiber. All the three different synaptic sites can transition from one kind of synaptic sites to another. A contact site formed by an axon has three different transition probabilities: a probability of transitioning into a vacancy (P_AV), a probability of transitioning into a tSC (P_AS), and a probability of no transition (P_AA = 1-P_AV-P_AS). Similarly, a contact site formed by a tSC has three different transition probabilities: a probability of transitioning into a vacancy (P_SV), a probability of transitioning into an axon (P_SA), and a probability of no transition (P_SS = 1−P_SA−P_SV). A vacant site also has three different transition probabilities: a probability of transitioning into a tSC (P_VS), a probability of transitioning into an axon (P_VA), and a probability of no transition (P_VV = 1−P_VS−P_VA).