BIO361 Somite Formation and Mesoderm Differentiation PDF

Figure 17.9 Neural tube and somites seen by scanning electron microscopy Paraxial Notochord Mesenchymal to epithelial Figure 17.3 Somites (Part 1) Paraxis (paraxial mesoderm) Pax2 (intermediate mesoderm) Chordin...

Figure 17.9 Neural tube and somites seen by scanning electron microscopy Paraxial Notochord Mesenchymal to epithelial Figure 17.3 Somites (Part 1) Paraxis (paraxial mesoderm) Pax2 (intermediate mesoderm) Chordin (notochord) BMP Figure 17.1 Major lineages of the mesoderm are shown in this schematic of the mesodermal compartments of the amniote embryo Figure 17.1 Major lineages of the mesoderm are shown in this schematic of the mesodermal compartments of the amniote embryo Figure 17.1 Major lineages of the mesoderm are shown in this schematic of the mesodermal compartments of the amniote embryo Figure 17.1 Major lineages of the mesoderm are shown in this schematic of the mesodermal compartments of the amniote embryo Figure 17.1 Major lineages of the mesoderm are shown in this schematic of the mesodermal compartments of the amniote embryo Figure 17.3 Somites (Part 2) Noggin/Chordin- expressing cells transplanted into lateral plate mesoderm Lateral plate mesoderm re- specified into paraxial/intermediate mesoderm Paraxial mesoderm patterns into somites! Figure 17.6 Antagonistic signals along the anterior-posterior axis pattern neuromesodermal progenitors (NMP) during paraxial mesoderm development (Part 2) Metameric NMPs NMP: Neuromesodermal progenitors; cells that contribute to neural tube formation and paraxial mesoderm Figure 17.11 Eph-Ephrin signaling regulates epithelialization during somite boundary formation A4 B2 Rostral Caudal Mesp: mesodermal posterior; initiates MET. Figure 17.12 Ephrin and its receptor constitute a possible fissure site for somite formation Time Figure 17.13 Somites form at the junction of retinoic acid (anterior) and FGF (posterior) domains Figure 17.13 Somites form at the junction of retinoic acid (anterior) and FGF (posterior) domains Fgf8 mRNA is located only in cells that transcribed the Fgf8 gene (bottom left). Class Question: Is Fgf8 protein cell autonomous or not? Figure 17.13 Somites form at the junction of retinoic acid (anterior) and FGF (posterior) domains Raldh2 mRNA is located only in cells that transcribed the Raldh2 gene (top left). Class Question: Is Raldh2 protein cell autonomous or not? Raldh2 Figure 17.13 Somites form at the junction of retinoic acid (anterior) and FGF (posterior) domains Mesp mRNA is located only in cells that transcribed the Mesp gene (top left). Class Question: Is the Mesp transcription factor cell autonomous or not? Somitogenesis in Zebrafish  Somite Clock Genetic Oscillations Oscillating waves of gene expression as seen in zebrafish One oscillation corresponds to the formation of one somite. In this case, one somite every 2.2 hours. Figure 17.15 Somite formation correlates with wavelike expression of the Hairy1 gene in the chick Hairy is a target of the Delta-Notch Pathway e.g., Hairy A proposed model for how the “Clock-Wavefront” phenomenon might work Growing posterior Fgf pERK Notch Mesp (one of several genes required for somite formation) Hes7 Model of the regulatory mechanisms governing somitogenesis Figure 17.20 Transverse section through the trunk of a chick embryo on days 2–4 (Part 1) Figure 17.20 Transverse section through the trunk of a chick embryo on days 2–4 (Part 2) Figure 17.20 Transverse section through the trunk of a chick embryo on days 2–4 (Part 4) Figure 17.21 Model of major postulated interactions in the patterning of the somite Figure 17.25 Induction of scleraxis in the chick sclerotome by Fgf8 from the myotome (Part 1) Notochord Figure 17.2 Gastrulation and neurulation in the chick embryo, focusing on the mesodermal component (Part 5) Tp= transverse process Pe= pedicle Figure 17.20 Transverse section through the trunk of a chick embryo on days 2–4 (Part 3) Figure 17.26 Primaxial and abaxial domains of vertebrate mesoderm (Part 3) Primaxial-derived Abaxial-derived