Dear Biology Students, Postdocs, and Faculty,
Next week for our Faculty Seminar Series at 1:00 p.m. on Monday, January 5th, we will have a talk by Dr. Ron Hadas of the Developmental and Synthetic Biology Division of Biology and Biological Engineering, Caltech, CA, USA . Dr. Ron Hadas will present a talk titled “How Do Extraembryonic Tissues Shape Development ?”.
Abstract
Mammalian embryogenesis progresses through rapid and coordinated diversification of embryonic and extraembryonic lineages, yet how progenitors emerge across time, space, and lineage remains unresolved. To address this, we built a temporal single-cell model of early development that delineates continuous differentiation trajectories in embryonic and extraembryonic compartments. Combined with targeted perturbations, this framework revealed an early bifurcation between early placental progenitors and a biphasic role for BMP4: an extraembryonic-derived signal essential for placental differentiation, mesoendoderm bifurcation, allantois formation, and germline specification, followed by an embryo-derived BMP4 signal that restricts the primordial germ cell pool.
Yet, transcriptional trajectories alone cannot reveal the actual lineage paths that cells take, or how spatial organization constrains these fate outcomes. To resolve these lineage relationships, we engineered MEMOIR, a spatial lineage-recording mouse model that integrates barcode editing, sequential imaging, and Bayesian methods for phylogenetic reconstruction. By retrospectively tracing lineage segregation events, MEMOIR charted epiblast diversification into germ layers, identified the origins of the primordial germline, and linked spatial position to fate choices in placental progenitors.
Together, these complementary approaches reveal how early development unfolds through coordinated signaling, spatial context, and lineage history. Understanding how gene programs generate distinct cell types provides a foundation for uncovering mechanisms of pregnancy failure and informing regenerative medicine strategies.
Looking forward to seeing you!
Maya
