Fig. 14. FM4-64 staining pattern of a L. longiflorum pollen tube grown under restrictive growth conditions. Confocal images of FM4-64 fluorescence are shown with corresponding bright-field images. (A) 15% sucrose medium (growth 8.7 µm/minute). (B) 25 mM calcium medium (growth <1 µm/minute), note the thickened apical cell wall. (C) Growth on 15 mM calcium medium (4.6 µm/minute). Bars, 15 µm.