Figure 1.

Formation of intercellular tethers in sparsely and densely plated cell cultures. 4T1 cells were sparsely (A and B) or densely plated (C and D) on tissue culture dishes, coated with 10 µg/ml fibronectin (FN), and incubated for 24 hrs. The attached cells were then fixed and observed, using Nomarsky optics (DIC) (A) or scanning electron microscopy (SEM) (B). The images show multiple membrane tethers that interconnect neighboring cells. Typical dimensions of the tethers are indicated by arrows and arrowheads in A. Inserts B’ and C’ display the marked regions in B and C, respectively, at higher magnification. It is noteworthy that in sparse cultures, cells display 1–2 unbranched tethers; in dense cultures, multiple branched tethers are seen. Scale bars: A and B = 10 µm; B’ = 2 µm; C = 5 µm; C’ = 1 µm.