Figure 2.

Fluorescence micrographs of hand-cut longitudinal fresh sections through the crease tissues after 2-h injections of 3-kD dextrans (R_s = approximately 1.2 nm). A, Distribution of 3-kD F-dextran. Unloading is fairly even along the phloem, and F-dextran has moved into the nucellus (nu). Except for some autofluorescence in the chalaza (ch), F-dextran accounts for virtually all of the fluorescence. B, Distribution of 3-kD R-dextran. Intercellular mobility is similar to that of 3-kD F-dextran; however, in contrast to the uniform within-cell fluorescence of 3-kD F-dextran, R-dextran is localized in globules, suggesting that it has been sequestered into a subcellular compartment, presumably the vacuole.