We also observed an increased cell density in Pkd1-/- tubes compared to Pkd1+/-, respectively, 94 ± 7 cells/10 000 μm2 (n = 10), vs. 53 ± 3 cells/10 000 μm2 (n = 22; p < 10–5), in line with the increased proliferation for the ADPKD model already reported in 2D. This evidence concerns the gene PKD1 and autosomal dominant polycystic kidney disease.