Time course and reversibility of epithelial stratification by the hydrostatic pressure.

<p>(A) A vertical section of MDCK I cell sheets. Hydrostatic pressure from basal to apical side was applied to the MDCK I cell sheets at two days after seeding on filters, and the vertical section of cell sheets was observed at Day 2 and 1–12 days after application of the hydrostatic pressure (Days 3–14). MDCK I cells showed gradual development of epithelial stratification with time. (B) The reversibility of epithelial stratification by the hydrostatic pressure. Hydrostatic pressure from basal to apical side was applied to the MDCK I cell sheets for four days, and the hydrostatic pressure gradient was then eliminated by the increase of the culture medium in the apical side. (C) Stratification index under the conditions in (A) and (B). The upper side is apical side and the lower side is basal side. Scale bars = 20 μm.