Metamorphosis

1 Metamorphosis: An Overview.- 1. Introduction.- 2. Primacy of the Spawning Environment.- 3. Internal or External Salinity—Which Determines the Visual Pattern?.- 4. Euryhaline Fishes and Amphibians.- 5. Biochemistry of Metamorphosis.- 6. Second Metamorphosis.- 7. Deep-Sea Fishes; Eels.- 8. Land Vertebrates.- 9. Conclusion.- 10. Epilogue.- References.- I: Insects.- 2 A Survey of Invertebrate Metamorphosis.- 1. Introduction.- 2. Invertebrate Metamorphoses.- 2.1. Porifera.- 2.2. Cnidaria.- 2.3. Ctenophora.- 2.4. Platyhelminthes.- 2.5. Nemertinea.- 2.6. Acanthocephala.- 2.7. Aschelminthes.- 2.8. Rotifera.- 2.9. Kinorhyncha.- 2.10. Priapulida.- 2.11. Entoprocta.- 2.12. Polyzoa.- 2.13. Brachiopoda.- 2.14. Annelida.- 2.15. Sipunculida.- 2.16. Echiurida.- 2.17. Arthropoda.- 2.18. Mollusca.- 2.19. Echinodermata.- 2.20. Phoronidea.- 2.21. Chaetognatha.- 2.22. Hemichordata.- 3. Comparison of Insect Metamorphosis with That of Other Invertebrates.- 3.1. Ametabolous Development.- 3.2. Hemimetabolous Development.- 3.3. Holometabolous Development.- 3.4. Hypermetamorphosis.- 4. Control of Metamorphosis.- 4.1. Larval Settlement and Metamorphosis.- 4.2. The Timing of Metamorphosis.- 5. Conclusions.- References.- 3 Cell Structure during Insect Metamorphosis.- 1. Introduction.- 1.1. The Nature of Metamorphosis.- 1.2. Definition of Terms.- 2. Tissue Reorganization.- 2.1. Metamorphic Changes in the Arrangement of Cells in Lepidopteran Fat Body.- 2.2. Changes in the Location of Cells—Epidermal and Muscle Rearrangement.- 2.3. Changes in Composition and the Distribution of Reserves.- 3. Cell Remodeling.- 3.1. The General Mechanism of Autophagy.- 3.2. Repopulation with New Organelles.- 3.3. Membrane Changes and Membrane Turnover.- 3.4. The Cytoskelton and Changes in Shape and Organelle Distribution.- 3.5. Cell Coupling and Junctions.- 3.6. The Control of Remodeling.- 4. Changes in the Numbers and Kinds of Cells in Remodeling to Make New Tissues.- 4.1. Cell Division.- 4.2. Cell Death.- 4.3. Polyploidy and Polyteny.- 5. The Morphology Needed to Explain Some Aspects of Metamorphosis.- 5.1. Hormonal Signals and the Response of the Nucleus.- 5.2. Positional Signals and the Kind and Amount of Growth.- 5.3. The Reception and Use of Nutritional and Precursor Molecules: Pinocytosis and Transepithelial Transport.- 6. Discussion.- 6.1. The Onset of Metamorphosis.- 6.2. Comparisons between Insects and Vertebrates.- References.- 4 Hormonal Control of Insect Metamorphosis.- 1. Introduction.- 2. Classical Methods for the Study of the Endocrinology of Insect Metamorphosis.- 3. The Insect Endocrine System: Structural Components of the Classical Scheme.- 3.1. The Brain—Neurosecretory Cells.- 3.2. Neurohemal Organs.- 3.3. Prothoracic Glands.- 3.4. Corpora Allata.- 4. Studies Leading to the Elaboration of the Classical Scheme.- 5. Chemistry and Endocrinology of the Metamorphic Hormones.- 5.1. Brain Hormone.- 5.2. Molting Hormones (Ecdysteroids).- 5.3. Juvenile Hormones.- 6. Control of Endocrine Glands.- 6.1. Cerebral NSC.- 6.2. The PG.- 6.3. The CA.- 7. Summary.- References.- 5 Chemistry, Metabolism, and Transport of Hormones Controlling Insect Metamorphosis.- 1. Introduction.- 2. Prothoracicotropic Hormone.- 3. Molting Hormone.- 3.1. Ecdysteroids—Chemistry and Occurrence.- 3.2. Biosynthesis of Ecdysone and 20-Hydroxyecdysone.- 3.3. Ecdysteroid Transport.- 3.4. Ecdysteroid Degradation.- 4. Juvenile Hormones.- 4.1. Chemistry and Occurrence.- 4.2. Structure-Activity Relationships.- 4.3. Transport.- 4.4. Biosynthesis.- 4.5. Degradation.- References.- 6 Macromolecular Changes during Insect Metamorphosis.- 1. Introduction.- 2. Changes in Protein and RNA during Larval-Pupal-Adult Metamorphosis.- 2.1. Breakdown of Macromolecular Components.- 2.2. Synthesis of Macromolecular Components.- 2.3. Cuticular Proteins.- 3. Pupal-Adult Metamorphosis: Wing Development.- 4. Larval-Pupal Metamorphosis.- 4.1. Epidermis.- 4.2. Fat Body.- Conclusions.- References.- 7 Drosophila Imaginal Discs as a Model System for the Study of Metamorphosis.- 1. Introduction and Background.- 1.1 General Characteristics of Mass-Isolated Imaginal Discs.- 2. Characteristics of Disc Metamorphosis.- 2.1. Late-Larval and Prepupal Development.- 2.2. Specificity of Ecdysteroid Induction of Disc Metamorphosis.- 2.3. Ecdysteroid Receptors in Imaginal Discs.- 2.4. Effects of Ecdysteroids on Discs.- 3. Discussion.- 3.1. Direct Nuclear Action of Hormones.- 3.2. Instability of Hormone-Receptor Complex.- 3.3. Multiplicity of Target Tissues.- 3.4. Evolutionary Origin of Metamorphic Hormone Responsiveness.- References.- 8 Cell Lines as a Model for the Study of Metamorphosis.- 1. Introduction.- 1.1. Advantages of Cell Lines.- 1.2. Cell Types Present in Established Cell Lines.- 2. Responses of Established Cell Lines to Ecdysteroids.- 2.1. Morphological Alterations.- 2.2. Enzyme Induction.- 2.3. Cell-Surface Changes.- 2.4. Cell-Cycle Changes.- 2.5. Ecdysteroid Receptors.- 3. Responses of Established Cell Lines to Juvenile Hormones.- 3.1. Proliferation and Morphological Effects.- 3.2. Macromolecular Synthesis.- 3.3. Juvenile Hormone Metabolism.- 3.4. Juvenile Hormone Receptors.- 4. Conclusions.- References.- II: Vertebrates.- 9 Survey of Chordate Metamorphosis.- 1. Introduction.- 2. Urochordates.- 2.1. Appendicularia.- 2.2. Thaliacea.- 2.3. Ascidians.- 2.4. Triggers of Metamorphic Climax.- 2.5. Unresolved Questions in Urochordate Metamorphosis.- 3. Cephalochordates.- 3.1. Cephalochordate Feeding Behavior.- 3.2. Triggers for Metamorphosis.- 3.3. Unresolved Questions in Cephalochordate Metamorphosis.- 4. Fish.- 4.1 Agnatha.- 4.2. Chondrichthyes.- 4.3. Osteichthyes.- 5. Amphibians.- 5.1. Parental Care.- 5.2. Larval Morphology and Staging.- 5.3. Larval Life Span and Survival Rates.- 5.4. Amphibian Larval Behavior.- 5.5. Triggers for Amphibian Metamorphosis.- 5.6. Problem Areas in Amphibian Metamorphosis.- 6. Future Work in Chordate Metamorphosis.- References.- 10 Cytological and Morphological Changes during Amphibian Metamorphosis.- 1. Introduction.- 2. The Thyroid.- 3. The Central Nervous System and Associated Notochord.- 3.1. General Development of the CNS.- 3.2. The Mauthner Cells.- 3.3. Lateral Motor Column Cells.- 3.4. Fine Structure of LMC Cells and Their Degeneration.- 3.5. Tail Nerve Cord.- 3.6. General Structure and Development of the Notochord.- 3.7. Notochordal Fine Structure and Its Degeneration.- 4. The Alimentary Canal.- 5. The Pancreas.- 6. The Liver.- 7. The Pronephros.- 7.1. Structure and Development.- 7.2. Fine Structure.- 7.3. Degeneration.- 8. The Skin.- 8.1. Early Epidermal Cellular Differentiation.- 8.2. General Structure of Larval Skin.- 8.3. Degeneration of Larval Tail and Body Skin.- 8.4. Thyroid Hormones and Larval Skin.- References.- 11 Hormonal Control of Amphibian Metamorphosis.- 1. Introduction.- 2. The Thyroid.- 2.1. Thyroid Function during Premetamorphosis.- 2.2. Thyroid Function during Prometamorphosis and Climax.- 2.3. Thyroid Function in Larval Urodeles.- 2.4. Metabolism of Thyroid Hormones.- 2.5. Tissue Sensitivity to T3 and T4.- 2.6. Pituitary Regulation of Thyroid Function.- 2.7. Control of Thyrotropic Function by Thyroid Hormonesm.- 2.8. Control of Thyrotropic Function by the Brain.- 2.9. Effects of Thyroid Hormones on Hypothalamo- Hypophysial Development and Function.- 3. Prolactin.- 3.1. PRL, GH, and Growth.- 3.2. Antimetamorphic Actions of PRL.- 3.3. PRL-Thyroid Interactions in “Second Metamorphosis”.- 3.4. Control of PRL Secretion and PRL Levels during Metamorphosis.- 4. Adrenocortical Hormones.- 5. Osmoregulation and Metamorphosis.- 6. Control of Anuran Development and Activation of Metamorphic Climax.- 7. Conclusions.- References.- 12 Biological Basis of Tissue Regression and Synthesis.- 1. Introduction.- 2. Spontaneous and Thyroid-Hormone-Induced Differentiation and Development of Anuran Tadpole Limbs and Lungs.- 2.1. Introduction.- 2.2. Tadpole Limbs.- 2.3. Tadpole Lungs.- 2.4. Conclusion.- 3. Spontaneous and Thyroid-Hormone-Induced Degeneration of Anuran Tadpole Tail and Gills.- 3.1. Introduction.- 3.2. Tadpole Tail.- 3.3. Tadpole Gills.- 3.4. Conclusion: Model for Hormone-Modulated Degeneration.- References.- 13 Transitions in the Nervous System during Amphibian Metamorphosis.- 1. Introduction.- 2. Gross Changes.- 3. Mesencephalic Fifth Nucleus.- 4. Mauthner’s Neuron.- 5. Lateral Motor Column.- 6. Dorsal Root Ganglia.- 7. Rohon-Beard Cells.- 8. Cerebellum.- 9. Sense Organs.- 10. Mitotic Activity.- 11. Behavioral Changes.- 12. Median Eminence.- 13. Conclusion.- References.- 14 Changes in the Blood during Amphibian Metamorphosis.- 1. Introduction.- 2. An Overview of Changes in Serum Proteins and Iron Metabolism.- 2.1. Changes in Blood Osmolarity, Serum Protein Concentration, and Serum Albumin.- 2.2. Changes in the Circulating Levels of Thyroid Hormones and Binding Proteins.- 2.3. Changes in Iron Transport, Metabolism, and Storage.- 3. Changes in the Hemoglobins and Red Blood Cells.- 3.1. Changes in Hb Structure and Function.- 3.2. Developmental Timing of the Hb Transition in Various Amphibians.- 3.3. Changes in Morphology and in Other Properties of the RBCs.- 4. Central Questions Pertaining to the RBC-Hb Transition in Bullfrogs.- 4.1. Do Adult and Larval Hbs Share Any Globin Chains?.- 4.2. Are Adult and Larval Hbs Contained in the Same RBCs during Metamorphosis?.- 4.3. Is the RBC-Hb Transition Mediated by a Change in Erythropoietic Sites?.- 4.4. Does the Life Span of RBCs Change during Metamorphosis?.- 4.5. Do Thyroid Hormones Have a Direct Effect on the Switch from Larval to Adult Globin Gene Expression?.- 4.6. What Is the Origin of the Stem Cells That Give Rise to Larval and Adult RBCs?.- 5. Summary.- References.- 15 Biochemical Characterization of Organ Differentiation and Maturation.- 1. Introduction.- 2. The Liver.- 2.1. DNA Synthesis, Cell Division, and Nuclear Morphology.- 2.2. Protein Synthesis, RNA Metabolism, and Cytoplasmic Morphology during Metamorphosis.- 2.3. Liver Glycogen.- 2.4. Mitochondrial Structure and Function during Metamorphosis.- 2.5. Temperature Effects on Liver Metamorphosis.- 2.6. Summary.- 3. The Kidney.- 4. The Intestine.- 4.1. Loss of Primary Epithelium and Shortening of the Gut.- 4.2. Proliferation of Secondary Epithelium and Development of Extraepithelial Tissues.- 4.3. Summary.- 5. The Integument.- 5.1. The Pigmentary System.- 5.2. Nonpigmentary Changes.- 6. The Eye.- 6.1. The Lens.- 6.2. The Retina.- 7. Summary and Conclusions.- References.- 16 The Dual Role of Thyroid Hormones in Vertebrate Development and Calorigenesis.- 1. Introduction.- 2. The Role of Iodine in Invertebrates.- 2.1. The Mystique of Iodine.- 3. Thyroid Hormone Dose-Response Relationships.- 4. Thyroid Hormone Receptors.- 5. Thyroid Hormone Effects in Poilcilothermic Vertebrates.- 6. Metamorphic Hormones in Amphibians.- 7. Thyroid Hormone Action in Birds.- 8. Metabolism and Calorigenesis.- 8.1. Hypo- and Hyperthyroidism.- 9. Thyroid Hormones and Differentiation.- 10. Mechanism of Action of Thyroid Hormones.- 10.1. Control of Nuclear Transcription and Protein Synthesis.- 10.2. Alternative Mechanisms of Thyroid Hormone Action.- References.