Figure 3
Thyroid carcinoma cell lines as model systems. Fluorescence micrographs of the papillary thyroid carcinoma cell line KTC-1 (A) and the anaplastic thyroid carcinoma cell lines HTh7 and HTh74 (B and C, respectively) taken with the confocal laser scanning microscope after fixation and phalloidin staining of the F-actin cytoskeleton. KTC-1 and HTh74 cells displayed stress fibers throughout the cytosol (A and C, arrows) as well as cortical F-actin underneath the plasma membranes. In HTh7 cells stress fibers were largely lacking (B) but cortical F-actin was displayed (B, arrowheads). KTC-1 cells grew in a monolayer fashion and established only a weak barrier as estimated by determination of the trans-epithelial electrical resistance (TER), whereas HTh7 cells formed non-tight monolayers and HTh74 cells grew in multilayers. Scale bars represent 20 µm.