Morphological appearance of P
EBEC liquid-liquid interface cultures before ALI creation. [a-b] Light microscopy of epithelial cell layers generated by freshly isolated cells (P0 insert cultures) (a) and by cells recovered from sub-confluent P0 cultures previously grown on solid supports in serum-containing medium (P1 insert cultures) (b) (objective magnification: ×4). [c-d] Representative scanning electron micrographs of P0 (c) and P1 (d) EBEC insert cultures: in P0 cultures (c) few ciliated cells, small amount of mucus and short microvilli can be observed; in P1 cultures (d) cells show poorly defined boundaries and many short microvilli. Scale bars = 2 μm. [e] Representative H&E staining of sections of epithelial layers grown on membrane inserts (objective magnification: ×20), showing that in both P0 and P1 cultures epithelial cells form a flat monolayer. Asterisk indicates the porous membrane support.