Reversal of epithelial polarity in piglet colon organoid. After 7 days of culture in Matrigel™ (A), piglet colon organoids were cultured in suspension for 24 h (B). Organoids were observed by confocal laser scanning microscopy to visualize horizontal (xy, A1 and B1) and vertical (xz, A2 and B2) sections. Phalloidin staining (red) shows actin and DAPI staining (blue) shows nuclei. Arrows indicate the apical side of epithelial cells. L Lumen.