All assays were performed on live cultures. The intact kidney rudiments were cultured at air liquid interface for 4 days following dissection. The organoids were cultured under medium immersion for six days following dissection. The samples cultured at air liquid interface were gently removed from the membranes before starting the assay. The samples were incubated for one hour at 25ºC with PBS containing 1uM 5(6)-Carboxyfluorescein (6-CF) and 20 ug/ml of PNA (Vector Laboratories). For the...