Figure 1. Calcium ion spiral waves in Xenopus oocytes.

Three frames have been chosen from a movie of an oocyte to show how the wave patterns evolve over time. These spectacularly patterned signals were first described by Lechleiter et al. (1991). Reproduced with permission of Professor James Lechleiter PhD: http://www.uthscsa.edu/csb/faculty/lechleiter.asp.