--- title: "HHMI Researchers Map Cellular Lineage of Developing Mice" url: https://newscentral.site/hhmi-researchers-map-cellular-lineage-of-developing-mice/ language: en publisher: "News Central Site" section: "Science" published: 2026-10-08T18:00:16.000Z updated: 2026-10-11T17:40:03.927Z id: e18c5e7d-99ef-47ea-91fd-c333c021dd47 source: "Phys.org https://phys.org/news/2026-10-cell-entire-mouse.html" attribution: "Link to https://newscentral.site/hhmi-researchers-map-cellular-lineage-of-developing-mice/ and name News Central Site when you quote or summarize this story." --- # HHMI Researchers Map Cellular Lineage of Developing Mice A team of researchers at HHMI has successfully created detailed cell fate maps for developing mice, providing valuable insights into how cells commit to their fates as the animal develops. A groundbreaking achievement in cell biology has been made by researchers at HHMI, who have successfully mapped the cellular lineage of developing mice. This milestone marks a significant step forward in understanding how a single fertilized egg gives rise to hundreds of millions of cells within just a few weeks. The complexity of this process is daunting, especially when considering that mammalian development differs greatly from simpler organisms like roundworms. While family trees have been constructed for these more transparent animals, creating a comprehensive cell fate map for a mammal has proven elusive, until now. Using innovative tools developed by Jonathan Weissman and Jay Shendure's teams, the researchers have managed to reconstruct cellular lineage maps spanning millions of cells in developing mice. This achievement represents the most complete lineage maps yet made for a mammal, providing valuable insights into how cells commit to their fates as the animal develops. The development of these new tools has enabled the creation of detailed family trees showing the relationships between individual cells and tracing their fate as the mouse grows inside its mother. The technique of tracking a cell's history through its genetic makeup has been adapted for use in mammals, allowing researchers to study complex developmental processes that were previously inaccessible. Weissman and his team have built upon earlier work done on roundworms, where the transparent nature of the embryo made it possible to observe every cell division under a microscope. However, mammalian embryos develop inside their mothers, rendering real-time observation impossible. To overcome this limitation, researchers engineered cells that can record their own history by adding permanent marks to their DNA each time they divide. These marks are then inherited by subsequent generations of cells, providing a record of ancestry that can be deciphered later on. The newly developed technique, PEtracer, was unveiled in 2025 and uses prime editing to install these marks at over 100 sites within the genome. This allows for a more comprehensive understanding of cellular relationships and developmental processes. By examining the accumulated marks in the DNA, researchers can reconstruct the complex family trees of individual cells as they divide and give rise to new cell types during embryonic development. The researchers used PEtracer to study mouse development by injecting engineered stem cells into an embryo. As the embryo developed, the heritable genetic marks were incorporated into nearly every cell it produced, providing a record of their lineage. This allowed the team to create massive cellular family trees that showed the different types of cells and their relationships to each other. The technology enables researchers to track how individual cells give rise to new cell types during embryonic development, revealing both where they came from and what they have become. In related research, a similar approach called DNA Typewriter was developed by Shendure's team at the University of Washington in 2022. The development of mammalian cells into complex tissues is a highly intricate process that has long fascinated scientists. Researchers now have access to advanced tools and maps that will allow them to better understand this process, including how cells differentiate to form various tissues. These new resources will enable researchers to study developmental diseases more effectively, pinpointing where and when an embryo is most susceptible to environmental or genetic stressors. This knowledge can be used to identify potential vulnerabilities in the development of tumors as well. The ability to record and infer information from DNA data also allows scientists to recreate the process of tumor initiation, growth, and spread. By doing so, researchers may gain valuable insights into how these processes occur and develop effective treatments. Researchers aim to use this data to train artificial intelligence models that can predict developmental outcomes, effectively creating a "virtual embryo" capable of simulating various scenarios. This virtual model could be used to identify potential risks and optimize treatment strategies. The development of these tools has also sparked excitement about the possibility of uncovering new biological discoveries. Weissman notes that such advances often lead to unforeseen breakthroughs, much like the mapping of the roundworm in the 1980s. The breakthroughs achieved by mapping the cell lineage of a mouse have been made possible by understanding the underlying molecular mechanisms that drive this process. A DNA Typewriter has successfully recorded the cell lineage history of a mouse from its zygote stage to late organogenesis, providing valuable insights into how a single cell can give rise to an entire organism. This achievement is documented in a recent study published under the title A DNA Typewriter records the cell lineage history of a mouse, with a DOI: 10.1126/science.ael0508 and also available on bioRxiv as DOI: 10.64898/2026.07.29.741625. --- Source: [Phys.org](https://phys.org/news/2026-10-cell-entire-mouse.html) Published by News Central Site: https://newscentral.site/hhmi-researchers-map-cellular-lineage-of-developing-mice/