Mathematical simulation and experimental measurement of dissolved O-2 were performed for extended (up to 8 h) shear testing of Daucus carota (carrot) cell cultures in a conventional Couette viscometer (0.625 mm annulus). The results suggest O-2 depletion below critical levels for cell growth may occur. A novel design modification incorporating an O-2-permeable silicone-layer spun cast on a porous ceramic bowl was devised. It significantly improved oxygenation of the cell cultures, keeping dissolved O-2 near saturation.