“Where Blood Begins: Decoding Early Embryonic Hematopoiesis”

Despite the central role of bone marrow in postnatal hematopoiesis, the first blood cells in mammalian development arise in the yolk sac, and their activity is essential for successful embryonic development. Progenitors of all three hematopoietic waves coexist in overlapping temporal and spatial windows and share many molecular markers, which makes their discrimination and study challenging. As a result, key aspects of early hematopoietic development remain unresolved. This presentation will focus on early embryonic hematopoiesis, particularly yolk sac–derived waves and their contribution to the developing immune system. Using a combination of single-cell RNA sequencing, flow cytometry, and novel lineage-tracing approaches based on the Split-Cre system, we aim to identify regulatory pathways, discover new progenitor markers, and refine strategies for tracking their developmental fate.