Transepithelial transport in cell culture. A theoretical and experimental analysis of the biophysical properties of domes.

Dissociated cells of transporting epithelia, when cultured on an impermeant substratum, form polarized monolayers frequently characterized by the presence of domes. If the assumption is made that the monolayer exhibits a uniform stretch modulus of elasticity and tension of cell-dish adhesion, Ta, then biophysical properties of the epithelium can be predicted. We have shown that for such epithelia, domes should (a) have circular bases, (b) be sections of spheres with a constant height to radius, h/r, ratio, (c) have a dome-wall tension, Tw, that is constant, and (d) have a dome volume that is a function of radius alone. Additionally, a Laplace equation derived for this geometry predicted the hydrostatic pressure from within to outside domes as a decreasing function of radius alone. By microscopy, domes had predominantly circular bases and were found to be sections of spheres with a constant height, h, to radius, r, ratio of 0.684. Using the Laplace equation derived for this geometry and measurements of delta P and r, the tension of cell-dish adhesion, Ta, and dome-wall tension, Tw, were found to be constants of 6.60 and 7.08 torr, respectively. Combining the constants for Ta and h/r ratio, and the fact that domes are sections of spheres, delta P and dome volume were shown to be known functions of radius alone. In addition, the modulus of elasticity of the epithelium was calculated to be 4.82 X 10(3) dyn/cm2.