Unambiguous observation of vesicle fusion in the interior of a cone

When a vesicle was put onto the inner surface of a cone, it would spontaneously move to the bottom of the cone. The mechanism was explained elsewhere. In this work, we showed that when we put two vesicles onto the inner surface of a cone, both of them would spontaneously climb to the bottom of the cone. What’s following is the unambiguous fusion of these two vesicles. The probability of fusion was greatly enhanced by the confined space and close contact between these two vesicles. Our result may shed new insights on the fusions of vesicles in complex environments in biological systems, especially in the axonal and nerve growth processes.