title: Tracing the first waves of lymphopoiesis in mice.
abstract: RAG1/GFP knock-in mice were used to precisely chart the emergence and expansion of cells that give rise to the immune system. Lymphopoietic cells detectable in stromal co-cultures arose as early as E8.5, i.e. prior to establishment of the circulation within the paraaortic splanchnopleura (P-Sp). These cells were Tie2+ RAG1- CD34(Lo/-) Kit+ CD41-. While yolk sac (YS) also contained lymphopoietic cells after E9.5, CD41+ YS cells from < or =25-somite embryos produced myelo-erythroid cells but no lymphocytes. Notch receptor signaling directed P-Sp cells to T lymphocytes but did not confer lymphopoietic potential on YS cells. Thus, definitive hematopoiesis arises in at least two independent sites that differ in lymphopoietic potential. Expression of RAG1, the earliest known lymphoid event, first occurred around E10.5 within the embryos. RAG1/GFP+ cells appeared in the liver at E11.0 and progenitors with B and/or T lineage potential were enumerated at subsequent developmental stages.
authors.affiliation: Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yokota
authors.forename: Jiaxue
authors.initials: J
authors.lastname: Huang
authors.forename: Manuela
authors.initials: M
authors.lastname: Tavian
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nagai
authors.forename: Jun
authors.initials: J
authors.lastname: Hirose
authors.forename: Juan-Carlos
authors.initials: JC
authors.lastname: Zúñiga-Pflücker
authors.forename: Bruno
authors.initials: B
authors.lastname: Péault
authors.forename: Paul W
authors.initials: PW
authors.lastname: Kincade
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D019070:Cell Lineage; D018920:Coculture Techniques; D004622:Embryo, Mammalian / Q000098:blood supply / Q000166:cytology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D008099:Liver / Q000196:embryology / Q000378:metabolism; D038041:Lymphopoiesis; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D040201:Platelet Membrane Glycoprotein IIb / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D042787:Receptor, TIE-2 / Q000378:metabolism; D013152:Splanchnic Circulation; D013234:Stem Cells / Q000166:cytology*; D017154:Stromal Cells / Q000166:cytology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology; D013950:Thymus Gland / Q000196:embryology / Q000378:metabolism; D015017:Yolk Sac / Q000166:cytology / Q000196:embryology / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D018398:Homeodomain Proteins; D040201:Platelet Membrane Glycoprotein IIb; C064658:RAG-1 protein; D049452:Green Fluorescent Proteins; D019009:Proto-Oncogene Proteins c-kit; D042787:Receptor, TIE-2