Mechanisms of target and spiral wave propagation in single cells.

Target and spiral wave propagation have been observed in single cells such as myocites. Moreover, in the same cells, transition from target waves to planar waves or from the latter to spiral waves was also observed. Considering an oscillatory medium described by the Ginzburg-Landau equation we suggest that such phenomena could be explained if cell nuclei and cell organelles are considered as obstacles in a small bounded medium. We discuss the role of cell geometry as well as the phenomenon of reentry at the cellular level.