Introduction to Molecular Embryology

Nearly 10 years have elapsed since I finished writing the first edition of Intro­ duction to Molecular Embryology. During this period, molecular embryology has made great strides forward, but without undergoing a major revolution; there­ fore, the general philosophy and outline of the book have remained almost un­ changed. However, all the chapters had to be almost completely rewritten in or­ der to introduce new facts and to eliminate findings which have lost interest or have been disproved. There was a major gap in the first edition of this book: very little was said about mammalian eggs despite their obvious interest for mankind. Research on mammalian eggs and embryos is so active today that this important topic deserves a full chapter in a book concerned with molecular embryology. Therefore, I am very thankful to my colleague Dr. Henri Alexandre, who has written a chapter on mammalian embryology (Chap. 9) and has prepared all the illustrations for this book.

I From Descriptive to Molecular Embryology.- II How Genes Direct the Synthesis of Specific Proteins in Living Cells.- III How Eggs and Embryos Are Made.- 1 Theories of Embryonic Differentiation.- 1.1 Summary of Descriptive Observations.- 1.2 A Few Important Experimental Facts.- 1.3 Genetic Theories of Morphogenesis.- IV Gametogenesis and Maturation: The Formation of Eggs and Spermatozoa.- 1 Oogenesis.- 1.1 Cytoplasm.- 1.2 The Nucleus (Germinal Vesicle: GV).- 1.2.1 The Nuclear Membrane.- 1.2.2 Chromosomes.- 1.2.3 Nucleoli.- 1.2.4 Nuclear Sap (Nucleoplasm).- 1.2.5 Xenopus Oocytes as Test-Tubes.- 2 Maturation of Xenopus Oocytes.- 3 Spermatogenesis.- V Fertilization: How the Sleeping Egg Awakes.- 1 General Outlook.- 2 The Fertilizin Problem.- 3 Physical and Chemical Changes at Fertilization.- 3.1 Early Changes.- 3.2 Later Biochemical Changes.- 3.2.1 Oxygen Consumption.- 3.2.2 Carbohydrate Metabolism.- 3.2.3 Protein Metabolism.- 3.2.4 Lipid Metabolism.- 4 Nucleic Acid and Protein Synthesis.- 4.1 DNA Synthesis.- 4.2 RNA Synthesis.- 4.3 Protein Synthesis.- 5 Parthenogenetic Activation.- 6 Molecular Embryology and Classical Theories of Fertilization.- VI Egg Cleavage: A Story of Cell Division.- 1 General Outlook.- 2 The Biochemistry of Cleavage.- 2.1 Energy Production.- 2.2 Chemical Nature of the Mitotic Apparatus.- 2.3 DNA Replication During Cleavage.- 2.4 RNA Synthesis During Cleavage.- 2.5 Protein Synthesis During Cleavage.- 2.6 Furrow Formation.- VII Molecular Embryology of Invertebrate Eggs.- 1 Chaetopterus Eggs.- 2 Mollusk Eggs.- 3 Tunicate (Ascidian) Eggs.- 4 Insect Eggs.- 5 Sea Urchins.- VIII Molecular Embryology of Amphibian Eggs.- 1 Respiration of the Amphibian Gastrula and Neurula.- 2 The Nature of the Inducing Substance.- 3 RNA Localization and Synthesis.- 4 The Links Between RNA Synthesis and Morphogenesis.- 5 Size and Mode of Action of the Inducing Agent.- 6 Molecular Basis of Cell Movements.- IX Molecular Embryology of Mammals.- 1 The Biology of Mammalian Sperm.- 1.1 Male Sex Determination in Mammals.- 1.2 Mammalian Spermatozoa from Testis to Fertilization.- 2 Molecular Embryology of Mammalian Eggs.- 2.1 Oogenesis.- 2.2 Maturation (Resumption of Meiosis).- 2.3 Preimplantation Period.- 3 Experimental Embryology of the Preimplantation Stages.- 4 Early Postimplantation Stages.- 4.1 Trophectoderm Differentiation.- 4.2 ICM Development.- 4.3 X Chromosome Inactivation.- 5 Interspecific Hybrids and Chimaeras.- X Biochemical Interactions Between the Nucleus and the Cytoplasm During Morphogenesis.- 1 Biology and Biochemistry of the Alga Acetabularia.- 1.1 Biological Cycle. Regeneration.- 1.2 Morphology of the Cytoplasm and the Nucleus.- 1.3 Biochemical Studies.- 1.3.1 Morphogenetic Substances and mRNAs: Experiments with Inhibitors.- 1.3.2 Energy Production.- 1.3.3 Protein Synthesis.- 1.3.4 RNA Synthesis.- 1.3.5 DNA Synthesis. Relative Autonomy of the Chloroplasts.- 1.3.6 Complexity of Nucleocytoplasmic Interactions.- 2 Biochemistry of Anucleate Fragments of Eggs.- 2.1 Amphibian Eggs.- 2.2 Sea Urchin Eggs.- 2.2.1 Biological Observations.- 2.2.2 Biochemical Studies.- 3 The Importance of the Nucleus for Embryonic Development.- 3.1 General Background.- 3.2 Lethal Hybrids.- 3.2.1 Biological Observations.- 3.2.2 Biochemical Studies on Lethal Hybrids.- 3.2.2.1 Respiration.- 3.2.2.2 Nucleic Acid and Protein Synthesis.- 4 Biochemistry of Early Developmental Mutants.- 5 “Transgenic” Mice and Teratocarcinoma.- 6 Conclusions.- XI How Cells Differentiate.- 1 General Introduction.- 2 Specific Properties of Cell Membranes.- 3 Effects of Tissue Extracts on Cell Differentiation.- 4 Immunological Studies on Embryonic Differentiation.- 5 Enzyme Synthesis and Embryonic Differentiation.- 6 Differentiation of Cultured Embryonic Cells.- 6.1 A Brief Description of a Few Biological Systems.- 6.2 Experimental Analysis of Cell Differentiation in Culture.- 6.2.1 Cell Fusion.- 6.2.2 Effects of Bromodeoxyuridine (BrdUr) on Cell Differentiation.- 6.2.3 Effects of Phorbol Esters and Retinoids.- 6.2.4 Other Inducers and Inhibitors of Cell Differentiation.- 7 Embryonic Differentiation and Cancer.- 8 The Future of Molecular Embryology.- References.- Further Reading.- Author and Subject Index.