We propose self-organizing transmission scheduling mechanisms for periodically gathering sensor data at a base station in wireless sensor networks. In our proposed mechanisms, sensor nodes self-organize message transmission and sleep timings. To propagate sensor data from the edge of the network to the base station in order of hop counts from the base station, we use a conventional self-organizing communication mechanism based on phase-locking in a pulse-coupled oscillator model. We propose two mechanisms to avoid collisions among sensor nodes with the same hop count, a randomization-based mechanism and a desynchronization-based mechanism based on anti-phase synchronization in the pulse-coupled oscillator model. Simulation experiments confirm that our mechanism significantly improves the data gathering ratio in comparison with the conventional mechanism.