In this study, we have mapped the onset of hematopoietic development in the mouse embryo using colony-forming progenitor assays and PCR-based gene expression analysis. With this approach, we demonstrate that commitment of embryonic cells to hematopoietic fates begins in proximal regions of the egg cylinder at the mid-primitive streak stage (E7.0) with the simultaneous appearance of primitive erythroid and macrophage progenitors. Development of these progenitors was associated with the expression of SCL/tal-1 and GATA-1, genes known to be involved in the development and maturation of the hematopoietic system. Kinetic analysis revealed the transient nature of the primitive erythroid lineage, as progenitors increased in number in the developing yolk sac until early somite-pair stages of development (E8.25) and then declined sharply to undetectable levels by 20 somite pairs (E9.0). Primitive erythroid progenitors were not detected in any other tissue at any stage of embryonic development. The early wave of primitive erythropoiesis was followed by the appearance of definitive erythroid progenitors (BFU-E) that were first detectable at 1–7 somite pairs (E8.25) exclusively within the yolk sac. The appearance of BFU-E was followed by the development of later stage definitive erythroid (CFU-E), mast cell and bipotential granulocyte/macrophage progenitors in the yolk sac. C-myb, a gene essential for definitive hematopoiesis, was expressed at low levels in the yolk sac just prior to and during the early development of these definitive erythroid progenitors. All hematopoietic activity was localized to the yolk sac until circulation was established (E8.5) at which time progenitors from all lineages were detected in the bloodstream and subsequently in the fetal liver following its development. This pattern of development suggests that definitive hematopoietic progenitors arise in the yolk sac, migrate through the bloodstream and seed the fetal liver to rapidly initiate the first phase of intraembryonic hematopoiesis. Together, these findings demonstrate that commitment to hematopoietic fates begins in early gastrulation, that the yolk sac is the only site of primitive erythropoiesis and that the yolk sac serves as the first source of definitive hematopoietic progenitors during embryonic development.

Barker
J. E.
(
1968
)
Development of the mouse hematopoietic system: I. Types of hemoglobin produced in embryonic yolk sac and liver.
Dev. Biol
18
,
14
29
Beaupain
D.
,
Martin
C.
,
Dieterlen-Lievre
F.
(
1979
)
Are developmental hemoglobin changes related to the origin of stem cells and site of hematopoiesis?.
Blood
53
,
212
225
Begley
C. G.
,
Green
A. R.
(
1999
)
The SCL gene: from case report to critical hematopoietic regulator.
Blood
93
,
2760
2770
Belaousoff
M.
,
Farrington
S. M.
,
Baron
M. H.
(
1999
)
Hematopoietic induction and respecification of A-P identity by visceral endoderm signaling in the mouse embryo.
Development
125
,
5009
5018
Brotherton
T.W.
,
Chui
D.H.K.
,
Gauldie
J.
,
Patterson
M.
(
1979
)
Hemoglobin ontogeny during normal mouse fetal development.
Proc. Natl. Acad. Sci. USA
76
,
2853
2857
Caprioli
A.
,
Jaffredo
T.
,
Gautier
R.
,
Dubourg
C.
,
Dieterlen-Lievre
F.
(
1998
)
Blood-bourne seeding by hematopoietic and endothelial precursors from the allantois.
Proc. Natl. Acad Sci. USA
95
,
1641
1646
Choi
K.
,
Kennedy
M.
,
Kazarov
A.
,
Papadimitriou
J.C.
,
Keller
G.
(
1998
)
A common precursor for hematopoietic and endothelial cells.
Development
125
,
725
732
Copp
A.J.
(
1995
)
Death before birth: clues from gene knockouts and mutations.
Trends Genet
11
,
87
93
Cormier
F.
,
Dieterlen-Lievre
F.
(
1988
)
The wall of the chick embryo aorta harbours M-CFC, G-CFC, GM-CFC and BFU-E.
Development
102
,
279
285
Cudennec
C. A.
,
Thiery
J.-P.
,
Le Douarin
N. M.
(
1981
)
In vitro induction of adult erythropoiesis in early mouse yolk sac.
Proc. Natl. Acad. Sci. USA
78
,
2412
2416
Cumano
A.
,
Dieterlen-Lievre
F.
,
Godin
I.
(
1996
)
Lymphoid potential, probed before circulation in mouse, is restricted to caudal intraembryonic splanchnopleura.
Cell
86
,
907
916
Dieterlen-Lievre
F.
(
1975
)
On the origin of hematopoietic stem cells in theavian embryo: an experimental approach.
J. Embryol. Exp. Morph
33
,
607
619
Downs
K. M.
,
Davies
T.
(
1993
)
Staging of gastrulating mouse embryos by morphological landmarks in the dissecting microscope.
Development
118
,
1255
1266
Dzierzak
E.
,
Medvinsky
A.
,
de Bruijn
M.
(
1998
)
Qualitative and quantitative aspects of haemopoietic cell development in the mammalian embryo.
Immunology Today
19
,
228
236
Haar
J. L.
,
Ackerman
G. A.
(
1971
)
A phase and electron microscopic study of vasculogenesis and erythropoiesis in the yolk sac of the mouse.
Anat. Rec
170
,
199
224
Hagopian
H. K.
,
Ingram
V. M.
(
1971
)
Developmental changes of erythropoiesis in cultured chick blastoderms.
J. Cell Biol
51
,
440
449
Houssaint
E.
(
1981
)
Differentiation of the mouse hepatic primordium. II. Extrinsic origin of the haemopoietic cell line.
Cell Differentiation
10
,
243
252
Johnson
G. R.
,
Barker
D. C.
(
1985
)
Erythroid progenitor cells and stimulating factors during murine embryonic and fetal development.
Exp. Hematol
13
,
200
208
Karasuyama
H.
,
Melchers
F.
(
1988
)
Establishment of mouse cell lines which constitutively secrete large quantities of interleukin 2, 3, 4 or 5, using modified cDNA expression vectors.
Eur. J. Immunol
18
,
97
104
Keller
G.
,
Kennedy
M.
,
Papayannopoulou
T.
,
Wiles
M. V.
(
1993
)
Hematopoietic commitment during embryonic stem cell differentiation in culture.
Mol. Cell. Biol
13
,
473
486
Kennedy
M.
,
Firpo
M.
,
Choi
K.
,
Wall
C.
,
Robertson
S.
,
Kabrun
N.
,
Keller
G.
(
1997
)
Identification of a common precursor for primitive and definitive hematopoiesis.
Nature
386
,
488
493
Lassila
O.
,
Martin
C.
,
Toivanen
P.
,
Dieterlen-Lievre
F.
(
1982
)
Erythropoiesis and lymphopoiesis in the chick yolk-sac-embryo chimeras: contribution of yolk sac and intraembryonic stem cells.
Blood
59
,
377
381
Medvinsky
A. L.
,
Gan
O. I.
,
Semenova
M. L.
,
Samoylina
N. L.
(
1996
)
Development of day-8 colony-forming unit-spleen hematopoietic progenitors during early murine embryogenesis: Spatial and temporal mapping.
Blood
87
,
557
566
Millauer
B.
,
Wizigmann-Voos
S.
,
Schnurch
H.
,
Martinez
R.
,
Moller
N. P. H.
,
Risau
W.
,
Ullrich
A.
(
1993
)
High affinity VEGF binding and developmental expression suggest flk-1 as a major regulator of vasculogenesis and angiogenesis.
Cell
72
,
835
846
Moore
M. A. S.
,
Metcalf
D.
(
1970
)
Ontogeny of the haemopoietic system: yolk sac origin in vivo and in vitro colony forming cells in the developing mouse embryo.
Br. J. Haem
18
,
279
296
Moore
M. A. S.
,
Owen
J. J. T.
(
1967
)
Chromosome marker studies inthe irradiated chick embryo.
Nature
215
,
1081
1082
Mucenski
M. L.
,
McLain
K.
,
Kier
A. B.
,
Swerdlow
S. H.
,
Schreiner
M. C.
,
Miller
T. A.
,
Pietryga
D. W.
,
Scott
W. J.
,
Potter
S. S.
(
1991
)
A functional c-myb gene is required for normal murine fetal hepatic hematopoiesis.
Cell
65
,
677
689
Muller
A. M.
,
Medvinsky
A.
,
Strouboulis
J.
,
Grosveld
F.
,
Dzierzak
E.
(
1994
)
Development of hematopoietic stem cell activity in the mouse embryo.
Immunity
1
,
291
301
Rich
I. N.
(
1992
)
The developmental biology of hemopoiesis: effect of growth factors on the colony formation of embryonic cells.
Exp. Hematol
20
,
368
370
Schuh
A. C.
,
Faloon
P.
,
Hu
Q. L.
,
Bhimani
M.
,
Choi
K.
(
1999
)
In vitro hematopoietic and endothelial potential of flk-1(−/−) embryonic stem cells and embryos.
Proc. Natl. Acad. Sci. USA
96
,
2159
2164
Shalaby
F.
,
Rossant
J.
,
Yamaguchi
T. P.
,
Gertsenstein
M.
,
Wu
X.-F.
,
Breitman
M. L.
,
Schuh
A. C.
(
1995
)
Failure of blood-island formation and vasculogenesis in Flk-1-deficient mice.
Nature
376
,
62
66
Shalaby
F.
,
Schuh
A. C.
,
Rossant
J.
(
1997
)
A requirement for Flk-1 in primitive and definitive hematopoiesis and vasculogenesis.
Cell
89
,
981
990
Silver
L.
,
Palis
J.
(
1997
)
Initiation of murine embryonic erythropoiesis: a spatial analysis.
Blood
89
,
1154
1164
Sonoda
T.
,
Hayashi
C.
,
Kitamura
Y.
(
1983
)
Presence of mast cell precursors in the yolk sac of mice.
Dev. Biol
97
,
89
94
Steiner
R.
,
Vogel
H.
(
1973
)
On the kinetics of erythroid cell differentiation in fetal mice: I. Microspectrophotometric determination of the hemoglobin content in erythroid cells during gestation.
J. Cell. Physiol
81
,
323
338
Turpen
J. B.
,
Knudson
C. M.
,
Hoefen
P. S.
(
1981
)
The early ontogeny of hematopoietic cells studied by grafting cytogenetically labeled tissue anlagen: localization of a prospective stem cell compartment.
Dev. Biol
85
,
99
112
Turpen
J. B.
,
Kelley
C. M.
,
Mead
P. E.
,
Zon
L. I.
(
1997
)
Bipotential primitive-definitive hematopoietic progenitors in the vertebrate embryo.
Immunity
7
,
325
334
Vandenbunder
B.
,
Pardenaud
L.
,
Jaffredo
T.
,
Mirabel
M. A.
,
Stehelin
D.
(
1989
)
Complementary patterns of expression of c-ets 1, c-myb and c-myc in the blood forming system of the chick embryo.
Development
106
,
265
274
Weiss
M. J.
,
Keller
G.
,
Orkin
S. H.
(
1994
)
Novel insights into erythroid development revealed through in vitro differentiation of GATA-1embryonic stem cells.
Genes Dev
8
,
1184
1197
Wilkinson
D. G.
,
Bhatt
S.
,
Herrmann
B. G.
(
1990
)
Expression pattern of the mouse embryo and its role in mesoderm formation.
Nature
343
,
657
659
Wong
P. M. C.
,
Chung
S.-W.
,
Chui
D. H. K.
,
Eaves
C. J.
(
1986
)
Properties of the earliest clonogenic hematopoietic precursors to appear in the developing murine yolk sac.
Proc. Natl. Acad. Sci. U.S.A
83
,
3851
3854
Wong
P. M. C.
,
Chung
S.-W.
,
Reicheld
S. M.
,
Chui
D. H. K.
(
1986
)
Hemoglobin switching during murine embryonic development: evidence for two populations of embryonic erythropoietic progenitor cells.
Blood
67
,
716
721
Yamaguchi
T. P.
,
Dumont
D. J.
,
Conion
R. A.
,
Breitman
M. L.
,
Rossant
J.
(
1993
)
flk-1, an flt-related tyrosine kinase is an early marker for endothelial cell precursors.
Development
118
,
489
498
Yoder
M. C.
,
Hiatt
K.
,
Dutt
P.
,
Mukherjee
P.
,
Bodine
D. M.
,
Orlic
D.
(
1997
)
Characterization of definitive lymphohematopoietic stem cells in the day 9 murine yolk sac.
Immunity
7
,
335
344
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