Figure 4.

Ca²⁺ homeostasis in the cytosol of PEMs. Fura-2-loaded pro-embryogenic cells were first perfused with MS₂ (MS + 1 mg/L 2,4-D) to establish the resting [Ca²⁺]_cyt. The cells were challenged (arrow) with: A, MS₃ (MS + 2% [w/v] mannitol); and B, MS₃ + 1 mm EGTA. Confocal time-based series of images that depict time-based alterations in Ca²⁺-bound dye fluorescence and free dye fluorescence in PEMs have been used to determine changes in [Ca²⁺]_cyt by the double wave length ratiometric analysis.