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Updated: Oct 28, 2026

Identification Of Erythromyeloid Progenitors And Their Progeny In The Mouse Embryo By Flow Cytometry
Published on: July 17, 2017
The maternal-fetal interface is an early hematopoietic niche enriched in distinct erythro-myeloid progenitors
Rohit Jain1,2,3, Shweta Tikoo4,5,6, Carlos Márquez-Burgoa7
1Department of Dermatology, Medical University of Vienna, Vienna, Austria. rohit.jain@meduniwien.ac.at.
Abstract:
Embryonic hematopoiesis is thought to occur exclusively in the extraembryonic yolk sac before hematopoietic stem cells (HSCs) arise in the aorta-gonad-mesonephros region. Here we identify a previously unrecognized hematopoietic site at the maternal-fetal interface in mice, termed MIXER (Maternally Interfaced eXtraEmbRyonic) tissue, which develops contemporaneously with the yolk sac and exhibits robust hematopoietic activity. MIXER contains abundant hematopoietic precursors, including classical CSF1R+ erythro-myeloid progenitors and a unique embryonic CD4+CSF1R- Erythro-Myeloid PRogenitOR (eEMPROR) population. Lineage-tracing experiments demonstrate that eEMPROR cells contribute to select macrophage subpopulations during fetal development, primarily in the perivascular space. Notably, early human placental villi, before HSC emergence, also harbor CD4+ nucleated erythrocytes, indicating a conserved hematopoietic role for the maternal-fetal interface. These findings establish MIXER as an anatomically distinct niche for embryonic hematopoiesis and expand the developmental map of blood cell emergence in mammals.
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