Fig. 3.

Penetration of BSA from the upper chamber of a transwell insert across the epithelium into the lower chamber. Total BSA content within the lower chamber is expressed as the percentage of the BSA in the upper chamber at various intervals from 1 to 24 h. Thus, a value of 100% represents total equilibration between the upper and lower chambers. BSA rapidly equilibrated across the Matrigel-coated membrane (No cells, n=4), slowly equilibrated across a layer of fibroblast-like non-epithelial cells (Non-epithelium, n=6) and showed negligible (<5%) penetration across the epithelial barrier (Epithelium n=6). The fibroblast-like cells were derived from cultures where the epithelium failed to attach and grow. Values fluctuated around zero, often with values less than matched control medium. Values represent the mean ± SEM