Claudins are the major constituents of tight junction (TJ) strands and participate in the cell-cell adhesion and permeability barrier in epithelial cell layers. To investigate the suitability of metanephroi for analysis of the function of the TJ protein claudins in renal tubular formation, mouse metanephroi from embryos at day 12 of gestation were cultured and expression of claudins was compared with that in embryonic kidneys. During in vitro culture for 8 days, the metanephroi showed expression patterns very similar to those observed in embryonic kidneys in reverse transcription-polymerase chain reaction for the claudins examined, including claudins 1-4, 8, 10, 11, and 16, and the TJ proteins occludin and ZO-1. Immunofluorescence microscopy for claudins 1-4, 8, 10, and 16 showed localization of these claudins at the TJ with occludin and ZO-1 in some restricted tubular segments. These findings indicate that the metanephroi show developmental changes in the expression of the TJ protein claudins, representing those in embryonic kidneys, and thus suggest that the mouse metanephros is suitable to examine the functions of specific claudins in the kidney.