Key aspects of aging biology remain mysterious. Does every tissue age at the same rate and in the same way? In this work, we applied the most recent advances in single-cell RNA sequencing in combination with a dissociation protocol to isolate worm cells in suspension (Zhang, Banerjee, and Kuhn, Plos One, 2011). Our goal was to address this question analyzing changes in gene expression regulation in every tissue across adulthood. Our final dataset contains 59,376 cells quantifying 24,297 genes at 6 ages ranging from day 1 of adulthood to day 15. We identified 211 unique expression states and matched these states to the majority of known cell types using systematic annotation. The quality of our cell identity annotation was validated by comparison to existing scRNAseq data and by using transgenic reporters in vivo. In young worms, we could assign functions to a few cell types whose expression was never accessible before. For instance, we observed that
uv1 and
uv3 vulva cells as well as GLR cell transcriptomes fell into neuronal categories. Moreover, we established a complete list of marker genes and candidate promoters for every cell type. We then analyzed the activities of 212 transcription factors (TFs) in every cell type, confirming some previously known TF activities (including
elt-7,
ces-1) and uncovering new ones (such as
hlh-15,
lin-32,
klf-2,
vab-15). The comparison across aging revealed a gene expression program that changes uniformly in the vast majority of cell types. This program includes genes previously found by bulk expression profiling (mitochondrial respiration, small heat shock proteins, vitellogenin and collagen). It also includes new transcription factors that appear to be functionally relevant. Interestingly, some critical GO-term gene-sets, like translation, nucleolus and proteasome have opposite aging trajectories among different tissues, suggesting that these tissues may age in fundamentally different ways. Our analysis also suggested that some tissues age faster than others, substantiated in vivo in preliminary experiments. All our data will be made publicly accessible online in a portal released upon publication.