PKD1 and cyst: Given the complexity and heterogeneity of Pkd1-mutant kidneys at these different stages, we next aimed to quantify the association between gene expression profiles in specific cell types and the variability in the pathological traits at each of the three stages of Pkd1 HOMO kidneys (day 7, pre-cyst; day 14, critical time point for cyst formation; day 21, aggressive cyst formation).