Cultured isolated mature gerbil Beta cells fire in synchrony, indicating that they reestablish gap junctions as they form cell clusters and monolayers. Islets of Langerhans from gerbils were enzymaticaly disaggregated into individual cells and thereafter cultured on a multi-electrode array (MEA). Simultaneous recording the electric activity from 60 external electrodes demonstrated that the cells generate wavelike electrical activity with amplitudes in the range of 20-300 mV and frequency of 0.3-2 Hz.   The time of appearance of activity in electrodes, which were connected by confluent monolayers, was studied using cross-correlation methods. The activity at the different electrodes could be correlated. A stable phase delay in time, that was consistent with propagation of activity across the monolayer, was demonstrated. Propagation velocity varied significantly in the range of 0.03 - 3.50 cm/sec, with an average of 0.27 cm/sec. The propagated activity was shown to originate from a consistent location, indicating the existence of a pace-maker.  Lowering glucose levels often resulted in migration of the pace-maker.  Propagation velocity as well as the firing frequency was found to be an inverse function of glucose concentration. The described method, that enables pinpointing the pace-maker location, may be used to characterize of the cells’ excitability attributes that make them potential pace-makers.