Fig. 2.

Engineered tubules display lumen formation and transport function at 2 days. (A) Z-stack images of the microtubule with a single lumen (l) in the central region. E-cadherin (red) is expressed by peripheral cells of the microtubule. (B) Three-dimensional reconstruction of z-stack images of an MDCK microtubule labeled with WGA-lectin. Two distinct z-stack series of captures from the top of the tubule to its centre and from the top to the centre of the other side were reconstructed and merged into the 3D composite image. The dashed line indicates the plane of image merging. (C) Cross-section of engineered microtubule showing the lumen (Lu) enclosed by epithelial cells with aligned nuclei and positive for WGA-lectin. (D) A branch from the macrotubular system with an extended lumen (Lu) enclosed by a monolayered epithelium positive for E-cadherin (red) and WGA-lectin (green) in the lateral and basal membranes, respectively (inset). (E–G) Microtubules showing (E) dextran (green) internalization and (F) 6CF (green) anion transport in the absence or (G) presence of the organic anion transporter inhibitor probenecid. WGA-lectin, wheat-germ agglutinin-lectin; 6CF, 6-carboxyfluorescein; DAPI, blue-stained nuclei. Scale bars: 10 μm (A, E–G insets), 100 μm (D,E), 50 μm (C,F,G), x,y, 500 μm, and z, 100 μm (B).