Note: Cover -- Half Title -- Title Page -- Copyright Page -- Table of Contents -- Series Preface -- Preface -- Acknowledgments -- Authors -- Section I: Development and Evolutionary Origin of the Notochord -- Chapter 1 Introduction to the Notochord and to Notochord Cells -- 1.1 Introduction -- 1.2 Structure of the Notochord -- A. Notochord Cells (Chordocytes) -- B. The Notochord Sheath -- 1.3 Function of the Notochord and Notochord Cells -- A. The Primary Chordate Axial Skeleton -- B. Signals for Neural and Ectodermal Induction -- C. Signals for Somitic Mesodermal Induction -- D. Integration of Axial Structures at the Phylotypic Stage -- E. Fate in Later Ontogeny -- 1.4 Differentiation of Notochord Cells -- A. Stack of Coins -- B. Notochord Epithelium -- C. Development of the Notochord Sheath -- 1.5 Notochord as Cartilage -- 1.6 Summary -- Chapter 2 Discovery and Evolutionary Origin of the Notochord -- 2.1 Introduction -- 2.2 Chordates -- A. Cephalochordates -- B. Tunicates -- 2.3 Hemichordates: A Phylum Outside the Chordates -- 2.4 Discovery that Amphioxus and Ascidians Possess a Notochord -- A. Amphioxus -- B. Ascidians (Tunicates) -- 2.5 Annelids as Chordate Ancestors -- A. The 1870s: Midline Structures, Segmentation and an Annelid Origin for Chordates -- B. The 20th C: Dorso-Ventral Inversion -- C. The 1990s: The Stomochord, Axochord and Gene-Based Homology Hypotheses -- 2.6 Vertebrates -- A. Albert Kölliker's 1859 Paper -- B. Notochord Structure and Function in Vertebrates -- 2.7 Searching for Chordates and Early Vertebrates in the Fossil Record -- A. Cambrian Fossils: Candidate Chordates -- B. Candidate Vertebrate: Jamoytius kerwoodi, Conodonts and the "Tully Monster" -- a. Jamoytius kerwoodi -- b. Conodonts -- c. The "Tully Monster" -- 2.8 Developmental Biology and Palaeontology -- 2.9 Summary. , Chapter 3 Germ-Layer Origin of the Notochord: Endoderm or Mesoderm -- 3.1 Introduction -- 3.2 The Notochord, Vertebral Column and Neural Tube -- 3.3 Developmental Origin of the Notochord -- A. Notochord as Endodermal -- B. Notochord as Mesodermal -- C. Notochord as Ectodermal -- D. Chordamesoderm and the Organizer -- E. The Dorsal Organizer -- F. The Anterior Notochord -- 3.4 The Notochord in Human Embryos -- 3.5 The Tail Bud, Secondary Neurulation and Secondary Notochord Extension -- 3.6 External Tails in Humans -- 3.7 Summary -- Section II: Function of the Notochord and Notochord Sheath -- Chapter 4 Function of the Notochord in Early Embryonic Development -- 4.1 Introduction -- 4.2 Midline Dorso-Ventral Organization: The Floor Plate -- 4.3 Notochord-Mesoderm Signaling Segregates Myotome from Sclerotome -- 4.4 The Notochord and Chondrogenesis of Sclerotomal Mesoderm in Tetrapods -- A. Removal or Transplantation of the Notochord and/or Neural Tube -- B. Molecular Signaling Cascades and Vertebral Chondrogenesis -- a. Shh, Noggin and Gremlin1 -- b. Pax1, Pax9 and Sox9 -- 4.5 Notochord Signaling and Vertebral Morphogenesis in Tetrapods -- A. Notochord, Neural Tube and Pax1 -- B. Notochord and Spinal Ganglia -- 4.6 Segmental Hox Gene Expression in the Teleost Notochord -- 4.7 Summary -- Chapter 5 Notochord Cells and Notochord Sheath Formation -- 5.1 Introduction -- 5.2 A Stack of Coins and the First Layer of the Notochord Sheath -- 5.3 The Notochord Sheath -- A. Notochord Sheath Formation -- B. Invasion of Cells into the Notochord Sheath -- 5.4 Notochord Cells -- A. The Notochord Epithelium -- B. Vacuolated Cells and the Expansion of the Notochord -- 5.5 The Amniote Notochord is Special -- A. The Notochord and what we Consider as Cartilage Matrix Components -- B. The Notochord Makes Cartilage Collagens, or the Other Way Round? -- 5.6 Summary. , Section III: Nature and Fate of the Notochord and Vertebrae across the Vertebrates -- Chapter 6 The Role of the Notochord in Vertebral Body Development -- 6.1 Do Somites Rule Over the Notochord? -- A. Resegmentation and Leaky-Resegmentation -- B. The Notochord and Vertebral Body Development -- 6.2 The Chordacentrum -- 6.3 In Half of All Vertebrate Species, Notochord Sheath Mineralization and Not Chondrogenesis Creates the Anlage of the Vertebral Centrum -- A. Are Notochord Signals Involved? -- B. How the Notochord Generates Vertebral Body Anlagen -- C. Variations of Vertebral Body Centra Anlagen Formation -- 6.4 How Common Is Notochord Sheath Mineralization? -- 6.5 Development of Cartilaginous Vertebral Bodies from the Notochord -- 6.6 A New Start of Vertebral Column Development -- 6.7 Summary -- Chapter 7 The Notochord in Adult Vertebrates -- 7.1 Introduction -- 7.2 Non-Constricted Notochords in Adult Vertebrates -- A. The Naked Notochord of Jawless Vertebrates -- B. Notochords of Extant Sarcopterygians -- C. Non-Constricted Notochords and Vertebral Centrum Regression -- 7.3 Constricted Notochords in Adult Vertebrates -- A. Notochord Constriction in Non-Mammalian Tetrapods -- B. Notochord Expansion Forms the Actinopterygian Intervertebral Disk -- C. A Neopterygian Notochord that Follows the Tetrapod Scheme -- D. Constricted and Non-Constricted Chondrichthyan Notochords -- 7.4 The Discontinuous Mammalian Notochord -- 7.5 Discontinuous Notochords in Non-Mammalian Vertebrates -- 7.6 Summary -- Section IV: Relationships: Notochord-Cartilage, Notochord-Vertebrae, Notochord-Vertebral Column -- Chapter 8 Relationships between Notochord and Chondrogenic Cells and Tissues: Transformational Series -- 8.1 Introduction -- 8.2 Shared Morphological Features of Notochord and Chondrogenic Cells. , 8.3 Similar Glycosaminoglycans in the Notochord Sheath and Cartilage Extracellular Matrix -- A. Notochord Secretes the Glycosaminoglycans of the Notochord Sheath -- B. Aggrecan -- C. Chondromodulin-1 -- 8.4 Similar Collagens in the Notochord Sheath and Cartilage Extracellular Matrix -- A. Collagen Type II -- B. Other Fibrillar Collagens -- C. Secretion of Type X Collagen -- 8.5 Shared Genes and Transcription Factors -- A. Brachyury -- B. Sox5 and Sox6 -- C. Sox9 -- 8.6 Transformations between Notochord and Chondrogenic Cells -- A. Chordoid and Chondroid -- B. Chordomas and Chondromas -- C. The Origins of Intervertebral and Intravertebral Cartilages -- a. Intervertebral Cartilage -- b. Intravertebral Cartilage -- D. Terminal Cartilaginous Notochord Extension -- 8.7 Notochord as a Type of Cartilage -- 8.8 Summary -- Chapter 9 The Notochord and Hypotheses about the Evolution of the Vertebral Column -- 9.1 The Notochord as Viewed in Life Science Disciplines -- 9.2 The Notochord's Struggle with the Arcualia Hypothesis -- 9.3 The Notochord and Autocentra -- 9.4 Centra from Notochord, Arches from Somites -- 9.5 The Fusion of Chordacentra and Autocentra -- 9.6 Joint Formation, a Key for Vertebral Column Homology -- 9.7 Summary -- References -- Index -- Series Page.