Self-Sustained Collective Oscillation Generated in an Array of   Non-Oscillatory Cells
  Oscillations represent a ubiquitous phenomenon in biological systems. The conventional models of biological periodic oscillations are usually proposed as interconnecting transcriptional feedback loops. Some specific proteins function as transcription factors, which in turn negatively regulate the expression of the genes that encode those "clock protein". These loops may lead to rhythmic changes in gene expression of a cell. In the case of multi-cellular tissue, the collective oscillation is often obtained from synchronization of these cells, which manifest themselves as autonomous oscillators. In contrast, here, we propose a different scenario for the occurrence of collective oscillation in a multi-cellular system independent of oscillation, neither intrinsically oscillatory cells nor periodic external stimulation. It is a coupling induced oscillation, with the consideration of wave propagation due to the intracellular communication. 
Yue Ma and Kenichi Yoshikawa