Figure 4
An example result based on a model of synaptic competition among axons, tSCs, and vacancies with random transition probabilities. (a) Initially, 9 different axons, tSCs and vacancies form their contact sites randomly in an endplate on a muscle fiber. The initial ratio of their total contact areas (axons:tSCs:vacancies) is about 30:16:54, which was determined from a previous serial electron microscopy study on developing muscle fibers of mouse during synapse elimination (See Methods). (b–h) The competition among axons, tSCs, and vacancies with their random transition probabilities shows elimination of multiple contact sites formed by different axons, tSCs, and vacancies at different iterations of the simulation (400, 500, 600, 700, 800, 1700, and 7600 iterations, respectively). (i) When the simulation reached 36500, synapse elimination is complete. However, only one type of axonal sites remains with no tSC and vacant sites that are present during and after synapse elimination of developing neuromuscular junctions. (j) The number of different types of contact sites in the endplate reduces sharply down to one as the iteration proceeds. (k) Change in the ratios of the contact areas formed by tSCs (green), vacancies (black), and 9 different axons (colors different from green and black) as the simulation based on a model of synaptic competition among axons, tSCs, and vacancies with random transition probabilities proceeds.
