Figure 4.

FITC-dextran uptake in polarized cells. Control and JAS-pretreated cells, grown on filters, were incubated with FITC-dextran added to either the apical or basolateral chamber for 15 min. Confocal microscopy shows endocytosed label at designated levels representing apical, middle, and basal levels of the cell monolayer. Little label was endocytosed from the apical side of either control (a–c) or JAS-treated (d–f) cells. A large amount of FITC-dextran was taken up from the basal medium and it was sequestered in structures at the basal and middle planes of control (h and i) and JAS-treated (k and l) cells. There was a marked increase in the number and size of labeled endocytic compartments in both the middle (k) and basal (l) planes after JAS treatment. Bar, 10 μm.