This communication describes the formation of tubular structures with a circular cross-section by growing epithelial cells in a microfluidic (MF) device. Here we show for the first time that it is possible to form a monolayer of polarized cells, embedded within the MF device which can function as an in vivo epithelia. We showed: i) the overexpression of specific protein(s) of interest (i.e., ion channel and transport proteins) is feasible inside tubular structures in MFs; ii) the functional kinetic information of Ca(2+) in cells can be measured by microflurometry using cell permeable Ca(2+) probe under confocal microscope; and iii) calcium phosphate stones can be produced in real time in MFs with Ca(2+) transporting epithelia. These data suggest that tubular structures inside this MF platform can be used as a suitable model to understand the molecular and pharmacological basis of calcium phosphate stone formation in the epithelial or other similar cellular micro environments.