A cell fate map of mammalian embryogenesis

A comprehensive cell fate map of mammalian embryogenesis has long been out of reach because of the scale, cellular diversity, and non-deterministic nature of development in utero. Using PEtracer to continuously install heritable genetic marks as cells divide, we reconstruct lineage trees that resolve roughly 75% of cell divisions.

Pairing these trees with deep transcriptional profiling, we quantify fate biases, restriction timing, progenitor pool sizes, and lineage relationships across the embryo — revealing strikingly reproducible lineage architecture across replicate embryos despite the regulative flexibility of mammalian development. The result is a lineage-resolved reference for generating and contextualizing developmental hypotheses at organismal scale.