10 Embryonic Patterning
of Xenopus Mesoderm by Bmp-4
C. Niehrs, R. Dosch, and D. Onichtchouk
10.1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 165
10.2 An Evolutionarily Conserved System for Dorsoventral Patterning 167
10.3
Bmp-4 Acts as a Morphogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 169
10.4 Downstream of Bmp-4: Xvent Homeoproteins and Smads .. . . .. 176
10.5 Perspective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 182
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 182
10.1 Introduction
During embryogenesis three germ layers - ecto-, meso-, and endoderm
- give rise to all somatic cells of the vertebrate body. From mesoderm,
the skeleton, muscle, connective tissue, heart, endocrine and exocrine
organs, blood, and the immune system develop. Mesoderm also plays a
critical role during axis formation in the vertebrate embryo. During
gastrulation, the early dorsal mesoderm, or Spemann organizer, has a
central inductive role. The Spemann organizer transplanted to the ventral side of a host embryo induces a twin embryo containing a complete
duplicated embryonic axis including the notochord, somites, and central
and peripheral nervous system. The organizer is also present in all other
vertebrates analyzed where it elicits comparable effects. In chicken and
mice this structure is the node, in fish the embryonic shield, which when
transplanted induces ectopic axial tissue (Storey et al. 1992; Beddington
1994; Shih and Fraser 1996). The organizer dorsalizes surrounding
of Xenopus Mesoderm by Bmp-4
C. Niehrs, R. Dosch, and D. Onichtchouk
10.1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 165
10.2 An Evolutionarily Conserved System for Dorsoventral Patterning 167
10.3
Bmp-4 Acts as a Morphogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 169
10.4 Downstream of Bmp-4: Xvent Homeoproteins and Smads .. . . .. 176
10.5 Perspective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 182
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 182
10.1 Introduction
During embryogenesis three germ layers - ecto-, meso-, and endoderm
- give rise to all somatic cells of the vertebrate body. From mesoderm,
the skeleton, muscle, connective tissue, heart, endocrine and exocrine
organs, blood, and the immune system develop. Mesoderm also plays a
critical role during axis formation in the vertebrate embryo. During
gastrulation, the early dorsal mesoderm, or Spemann organizer, has a
central inductive role. The Spemann organizer transplanted to the ventral side of a host embryo induces a twin embryo containing a complete
duplicated embryonic axis including the notochord, somites, and central
and peripheral nervous system. The organizer is also present in all other
vertebrates analyzed where it elicits comparable effects. In chicken and
mice this structure is the node, in fish the embryonic shield, which when
transplanted induces ectopic axial tissue (Storey et al. 1992; Beddington
1994; Shih and Fraser 1996). The organizer dorsalizes surrounding