Culture single cell, polarity

Epithelial cells are cells covering the body surface and bounding cavities, e.g. the gut or kidney tubules. They are bound together laterally by tight junctions to form sheets of cells and their apical and basolateral surfaces differ in composition and are kept apart by the tight junctions. They have the ability to transport solutes across the cell sheet from the apical surface. Of course, in culture a single epithelial cell cannot exhibit these properties but as the cells divide they form stable clusters of tightly associated cells and monolayers of such cells do show polarity. This is most easily achieved in serum-free, hormonally defined medium ( 5.8) when differentiated... 

Ordinary monolayer cultures may provide quite misleading information about these processes, because, in some types of polarized epithelial cells, the microtubules do not radiate from a single nucleating center, but run vertically... 

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