Insect Ultrastructure

Cell biology is moving at breakneck speed, and many of the results from studies on insects have helped in understanding some of the central problems of biology. The time is therefore ripe to provide the scientific community with a series of up-to-date, well illustrated reviews of selected aspects of the sub­ microscopic cytology of insects. The topics we have included fall into four general groups: seven chapters deal with gametogenesis, four concern develop­ ing somatic cells, seventeen chapters describe specialized tissues and organs, and three chapters cover cells in pathological states. These accounts are illustrated with over 600 electron micrographs. The more than 1100 pages in the two volumes of Insect Ultrastructure combined labors of 49 dedicated contributors from II countries. represent the These authors have digested and critically summarized a very large body of information, and some measure of this effort can be gained from consulting the bibliographies that close each of the 31 chapters. These contain 2400 publica­ tions authored by 1500 different scientists. However, before we congratulate ourselves on the advanced state of our knowledge, it is worth remembering that representatives of less than 0.01 % of the known species of insects have been examined with the electron microscope.

I. The Ultrastructure of Developing Cells.- 1 The Ultrastructure and Development of the Telotrophic Ovary.- 1. Introduction.- 1.1. Groups Having Telotrophic Ovaries.- 2. Adult Ovary—General Aspects.- 3. Ovarian and Ovariole Sheaths, Tunica Propria, and Terminal Filaments.- 4. Inner Sheath or Interstitial Cells.- 5. Tropharium—General Features and Nurse Cell Functions.- 5.1. Nurse Cell Nuclear Morphology.- 5.2. Nurse Cell Cytoplasm.- 6. Tropharium—Arrangement of Nurse Cell Compartments.- 7. Trophic Cords or Trophic Tubes.- 8. Nurse Cell-Oocyte Interaction: Transport Regulation and Mechanisms.- 9. Oocytes: General Features, Nuclear Morphology, Cortex Morphology.- 10. Follicle Cells.- 11. Adult Ovary Summary.- 12. Ovarian Development: General Aspects.- 13. Postembryonic Early or Larval Ovary Stages: Mitotic Growth and Establishment of Somatic Tissue-Germ Cell Interaction.- 14. Postembryonic Late Ovary Stages: Larval-Adult Transformation, Nurse Cell, and Oocyte Differentiation.- 15. Summary.- References.- 2 Early Embryogenesis of Bombyx mori.- 1. Introduction.- 2. The Structure of Mature Eggs from the Oviduct.- 2.1. The Micropylar Region.- 2.2 Other Egg Regions.- 3. Maturation and Fertilization.- 3.1. Structure of Sperm in the Spermatheca.- 3.2. Changes of the Vitelline Membrane and Periplasm Accompanying the Entry of Sperm.- 3.3. The Sperm and Egg Nuclei.- 4. Cleavage and Blastoderm Formation.- 4.1. The Cleavage Stage.- 4.2. The Formation of Blastoderm Cells.- 4.3. The Vitellophages.- 5. Formation of the Germband and the Embryonic Envelopes.- 5.1. TheGermband.- 5.2. The Serosa and the Amnion.- 6. Summary.- References.- 3 Electron Microscopic Mapping and Ultrastructure of Drosophila Polytene Chromosomes.- 1. Introduction.- 2. Light Microscopic Maps of the Salivary Gland Chromosomes of Drosophila melanogaster.- 3. Electron Microscopic Methods for the Mapping of Polytene Chromosomes.- 3.1. Thin-Sectioning of Squashed Chromosomes.- 3.2. Electron Microscopy of Whole-Mounted Polytene Chromosomes.- 4. Electron Microscopic Maps of the Salivary Gland Chromosomes of Drosophila melanogaster.- 5. Ultrastructural Studies on Drosophila Polytene Chromosomes.- 5.1. Ultrastructure of Interbands.- 5.2. Ultrastructure of Bands.- 5.3. Functional Organization of Polytene Chromosomes.- 6. Local Variation of the Degree of Polyteny.- 7. Summary.- References.- II. The Ultrastructure of the Development, Differentiation, and Functioning of Specialized Tissues and Organs.- 4 The Structure of Insect Muscles.- 1. Introduction.- 2. Contractile System.- 2.1. Myofilament Organization and Disposition.- 2.2. Z-Band Structure and Supercontraction.- 2.3. Paramyosin and Connecting Protein.- 3. Muscle Insertions.- 4. Membrane Systems.- 4.1. General Features.- 4.2. Synchronous Muscles.- 4.3. Asynchronous Muscles.- 5. Tracheation.- 6. Summary.- References.- 5 The Structure and Development of the Vacuolar System in the Fat Body of Insects.- 1. Introduction.- 1.1. The Fat Body.- 1.2. The Ultrastructure of Fat Body Cells.- 1.3. The Fat Body Vacuolar System.- 1.4. Kinds of Fat Body Vacuole.- 2. Posttransition Compartments.- 2.1. Tyrosine Storage Vacuoles and Provacuoles.- 2.2. Urate Storage Vacuoles.- 2.3. Urate Granules.- 2.4. Protein Storage Granules.- 2.5. Secretory Vesicles.- 2.6. Vacuoles Containing Symbionts.- 2.7. Vacuoles Associated with Glycogen.- 2.8. Autophagic Vacuoles.- 2.9. Multivesicular Bodies.- 2.10. Lamellar Bodies.- 2.11. Basal Lamina Phagocytic Vacuoles.- 3. Pretransition Compartments.- 3.1. Distensions of the RER.- 3.2. Peroxisomes.- 3.3. Concretions in the RER.- 4. Discussion.- 5. Summary and Conclusions.- References.- 6 The Ultrastructure of the Digestive and Excretory Organs.- 1. Introduction.- 2. The Midgut: General Organization.- 2.1. Structure of the Wall.- 2.2. Striated Border.- 2.3. Basement Membrane (Basal Lamina) and Related Structures.- 3. Types of Epithelial Cells in the Midgut.- 3.1. Columnar Cells.- 3.2. Goblet Cells.- 3.3. Peculiar Secretory Cell Types: The Goblet Cells of Thysanura and the Bottle-Shaped Cells of Odonata.- 3.4. Endocrine Cells.- 3.5. Storage Products of the Columnar Cells.- 3.6. Secretion of the Peritrophic Membrane.- 4. Changes in Fine Structure.- 4.1. Functional Subdivisions of the Gut and Cellular Cycles.- 4.2. Effects of Unsuitable Diets and Starvation.- 4.3. Blood-Sucking Insects.- 5. Cell Degeneration and Renewal.- 5.1. Cell Degeneration.- 5.2. Cell Differentiation.- 5.3. Differentiation of Microvilli in Embryonic Cells.- 5.4. Peculiar Aspects of Metamorphosis in Some Holometabola.- 6. The Proctodeal Fermentation Chambers.- 7. Filter Chambers and Related Organs.- 7.1. Midgut Filter Chambers.- 7.2. The Composite Segment of Termite Intestines.- 8. The Salivary Glands.- 8.1. The Tubular Glands of Adult Flies.- 8.2. The Tubular Salivary Glands of Adult Lepidoptera.- 8.3. The Tubular Salivary Glands of Mosquitos.- 8.4. The Acinar Glands of Dictyoptera and Orthoptera.- 8.5. The Sac-Shaped and Tubular Salivary Glands of Lower Diptera.- 9. The Malpighian Tubules.- 9.1. The General Organization of the Malpighian Tubules.- 9.2. Types of Cells.- 9.3. Compounds Deposited in the Lumen of the Tubules.- 10. The Proctodeum.- 10.1. General Organization of the Epithelium.- 10.2. Types of Epithelial Cells.- 11. The Pericardial Cells.- 12. The Other Excretory Organs.- 13. Concluding Remarks.- References.- 7 The Ultrastructure of Interacting Endocrine and Target Cells.- 1. Introduction.- 2. The Insect Endocrine System.- 3. The Ultrastructure of the Endocrine Glands of Manduca.- 4. The Corpora Allata.- 4.1. Synthesis of Juvenile Hormone.- 4.2. Secretion of Juvenile Hormone.- 4.3. Axons of PTTH Release.- 4.4. Degradation of Juvenile Hormone.- 5. Prothoracic Glands.- 5.1. Synthesis of Ecdysone.- 5.2. Secretion of Ecdysone.- 5.3. Stimulation of Prothoracic Glands by PTTH.- 5.4. Stimulation of Prothoracic Glands by 20HE.- 6. Summary of Gland Cell Structure.- 7. Target Tissue: Epidermal Cells and Cuticle Secretion.- 7.1. Hormonal Influences on the Epidermis.- 7.2. Effects of Ecdysteroids on the Epidermis.- 7.3. Effects of Juvenile Hormone on the Epidermis.- 8. Summary of Target Tissue Responses to Hormones.- 9. Conclusions.- References.- 8 The Fine Structure of Insect Glands Secreting Waxy Substances.- 1. The Waxy Secretions of Insects.- 1.1. Chemical Properties.- 1.2. Site of Synthesis of Waxy Secretions.- 1.3. The Function of Insect Waxes.- 1.4. The Economical Importance of Insect Waxes.- 2. Classification of Wax Glands.- 2.1. Classification of Epidermal Glands.- 2.2. Simple Wax Glands.- 2.3. Complex Wax Glands.- 2.4. The Mechanism of Pattern Formation by the Products of Wax Glands.- 3. Development of Wax Glands.- 4. Taxonomic Importance of Wax Glands.- References.- 9 The Ultrastructure and Functions of the Silk Gland Cells of Bombyx mori.- 1. Introduction.- 2. The General Cytology of the Silk Gland.- 3. The Ultrastructure and Functioning of the Silk Gland Cells.- 3.1. Posterior Silk Gland.- 3.2. Middle Silk Gland.- 3.3. Anterior Silk Gland.- 3.4. Filippi’s Gland.- 3.5. Liquid Silk and the Cocoon Filament.- 4. The Hormonal Control of Silk Gland Development.- 5. Mutations Influencing Silk Production.- 6. Summary.- References.- 10 Structure and Development of Male Accessory Glands in Insects.- 1. Introduction.- 2. Accessory Glands and Their Secretions.- 3. Muscular Coats and Basement Membranes.- 4. The Secretory Epithelia.- 4.1. Intercellular Junctions.- 4.2. Absorption of Precursors.- 4.3. Biosynthetic Machinery.- 4.4. Export of Product.- 5. Semisolid Secretory Products.- 5.1. Organized Secretion Masses.- 5.2. Secretion into Separate Compartments Arranged in Series.- 5.3. Secretion in Parallel to a Common Lumen.- 6. Formation of the Spermatophore.- 7. Evacuation of the Spermatophore.- 8. Development of Accessory Glands.- 9. Endocrine Control of Accessory Gland Development.- 10. Summary and Prospects.- References.- 11 The Photoreceptor Cells.- 1. Introduction.- 2. Historical Record.- 3. Ommatidial Morphology.- 4. Photoreceptor Fine Structure.- 5. Ultrastructure of the Cell Soma.- 5.1. Rhabdom.- 5.2. Nucleus.- 5.3. Endoplasmic Reticulum.- 5.4. Screening Pigment Granules.- 5.5. Mitochondria.- 5.6. Golgi Material.- 5.7. Ciliary Structures.- 5.8. Other Intracellular Structures.- 6. Cells Associated with Photoreceptor Cells.- 7. The Axon.- 8. The Synapse.- 8.1. Chemical Synapses.- 8.2. Electrical Synapses.- 9. Concluding Remarks.- References.- 12 The Glial Cells of Insects.- 1. Introduction.- 1.1. Historical Concepts of Neuroglia.- 1.2. Insect Neuroglia: General Concepts.- 1.3. The Insect Eye.- 2. Ultrastructure of Insect Neuroglia.- 2.1. The Nucleus.- 2.2. Cytoplasmic Organelles.- 2.3. Elaborations of the Plasma Membrane.- 2.4. Interglial Junctions.- 3. Specialized Supporting Cells of the Insect Eye.- 3.1. Pigmented Glia.- 3.2. Tracheal Cells.- 4. Neuro-glial Junctions.- 4.1. Desmosomes.- 4.2. Septate Junctions.- 4.3. Scalariform Junctions.- 4.4. Tight Junctions.- 4.5. Gap Junctions.- 5. Structure-Function Relationships.- 5.1. Structural Support.- 5.2. The Blood-Brain Barrier and Ionic Homeostasis.- 5.3. Metabolic Commerce.- 5.4. Phagocytosis.- 5.5. Glia in Neurogenesis.- 5.6. Compartmentalization of Neuropil.- 6. Concluding Remarks.- References.- 13 Mechanosensitive and Olfactory Sensilla of Insects.- 1. Introduction.- 2. General Organization and Morphogenesis of Sensilla.- 3. Fine Structure of the Cellular Components of Sensilla.- 3.1. The Sensory Neurons.- 3.2. The Auxiliary Cells.- 3.3. Membrane Contact Structures.- 3.4. The Receptorlymph Spaces.- 3.5. Glia Cells and Neuron-Glia Interrelations.- 4. Fine Structure of Mechanosensitive Sensilla.- 4.1. General Remarks.- 4.2. Cuticular Parts.- 4.3. Cellular Parts.- 4.4. Stimulus Uptake and Transmission.- 4.5. The Macrochaetae of Calliphora.- 4.6. Filiform and Clavate Hairs on the Cerci of Acheta.- 5. Fine Structure of Olfactory Sensilla.- 5.1. General Remarks.- 5.2. Single-Walled Olfactory Sensilla with Pore Tubules.- 5.3. Double-Walled Olfactory Sensilla with Spoke Channels.- 6. Final Remarks.- References.- 14 The Cytopathology of Baculovirus Infections in Insects.- 1. Introduction.- 2. Mode of Virus Infection.- 3. Gross Pathology of Nuclear Polyhedroses of Lepidoptera.- 4. Gross Pathology of Nuclear Polyhedroses of Hymenoptera.- 5. Gross Pathology of Nuclear Polyhedroses of Diptera.- 6. Gross Pathology of Granuloses.- 7. Gross Pathology of Baculovirus of Oryctes.- 8. Gross Pathology of Parasitoid Baculovirus.- 9. Cytopathology of Occluded NPV in Lepidoptera.- 10. Cytopathology of Occluded NPV in Hymenoptera.- 11. Cytopathology of Occluded NPV in Diptera.- 12. Cytopathology of Granuloses.- 13. Cytopathology of Nonoccluded NPV in Oryctes rhinoceros.- 14. Cytopathology of Nonoccluded NPV in Gyrinus natator.- 15. Cytopathology of Nonoccluded NPV of Parasitoids.- 16. Summary.- References.- III. The Ultrastructure of Cells in Pathological States.- 15 Comparative Ultrastructure of Wild-Type and Tumorous Cells of Drosophila.- 1. Introduction.- 2. Comparative Ultrastructure of Wild-Type and Tumorous Imaginal Discs.- 3. Comparative Ultrastructure of Wild-Type and Malignant Optic Neuroblasts and Ganglion Mother Cells.- 3.1. Ultrastructure of the Neuroblasts and Ganglion Mother Cells in the Mature Wild-Type Larval Brain.- 3.2. Ultrastructure of the Neuroblasts and Ganglion Mother Cells in the Mature l(2)gl4 Larval Brain.- 4. Comparative Ultrastructure of Wild-Type and Tumorous Blood Cells.- 4.1. Ultrastructure of Blood Cell Precursors in the Hematopoietic Organs and of the Free Blood Cells in the Hemolymph of Wild-Type Larvae.- 4.2. Ultrastructure of Tumorous Blood Cells.- 5. Discussion.- References.- 16 The Cellular Defense System of Drosophila melanogaster.- 1. Introduction.- 2. Distribution of Hemocytes in the Larva.- 3. Classification of the Larval Hemocytes.- 3.1. The Plasmatocyte and Its Variants.- 3.2. The Crystal Cell.- 4. Crystal Cells in Other Drosophila Species.- 5. Phagocytosis.- 5.1. Cell Disruption as a Source of Humoral Factors.- 5.2. Absence of Opsonization in Phagocytosis.- 5.3. A Mutation Affecting Phagocytosis.- 6. Encapsulation.- 6.1. Capsule Formation in Melanotic Tumor Mutants.- 6.2. Basement Membrane as a Factor for Recognition of Self.- 6.3. Ultrastructural Examination of Basement Membrane.- 7. Differentiation of Competent Lamellocytes.- 8. Contribution of Crystal Cells to Melanization Reactions.- 9. Wound Healing.- 10. Genetic Dissection of the Cellular Defense System.- 11. Summary and Concluding Remarks.- References.- Author Index.