Fig. 1. scRNA-seq reveals shared cell types present across postembryonic stages.

a Schematic phylogeny of bilaterians with a cnidarian outgroup based on published literature¹¹² highlighting the presence of adult pluripotent stem cells (aPSCs) across multiple metazoan lineages as well as the origin of bilateria ~550 million years ago (mya). Silhouettes of animals were modified from phylopic. Credit to B. Duygu Özpolot (tunicate and annelid) and Markus A. Grohme (planarian). b Life cycle schematic of Hofstenia miamia. Hofstenia embryogenesis takes about 8–9 days, and postembryonic development until sexual maturity (animals are hermaphroditic) takes about 6 weeks. The postembryonic stages are divided into 4 distinct stages: hatchling juvenile, late juvenile, early adult, and late adult. c Venn diagram of Hofstenia cell types detected across different postembryonic stages. There are 11 cell types that are consistent across postembryonic development. d Uniform Manifold Approximation and Projection (UMAP) representation of the hatchling juvenile scRNA-seq data set with the 11 cell types that were found consistent across stages. Gray clusters represent cell types that were not consistent across stages. e Fluorescent in situ hybridization of selected markers corresponding to each of the 11 shared identified cell types. Scale bars 100 µm.