Fig. 2. High-speed confocal microscopy of dissociated rat parotid gland showing calcium signalling of acini and ducts in response to CCh. (A) Fluorescence image. (B) Merged image of transmitted light and fluorescence image shown in A. (C) Quantitative measurement of the fluorescent changes calculated from the pseudo-ratio imaging. Data were obtained from the correspondingly numbered squares shown in A. (D,E) Sequential changes of fluo-3 fluorescence following addition of CCh. Acinar response precedes the ductal response. An arrow denotes `pioneer' cells from which the ductal response is initiated. CCh was applied at time zero. Confocal images were taken every 8 milliseconds.