The most striking fact revealed by investigations of insect neurohormones is that insects are as well supplied with neurohormones as mammals, since neurohor­ mones regulate not only the functioning of the endocrine glands, prothoracic gland, and corpora allata, but also most physiological processes. Our knowledge of neurohormones developed originally from anat­ omocytological investigations and experimental studies. Today, accurate bio­ assays have been devised for studying both in vivo and in vitro physiological processes, and RIA determination has yielded knowledge of titer modifications of humoral factors. Much is also known about neurohormone purification, and several neurohormones have even been identified in different species. Immunocytochemistry has made it possible to demonstrate in their origin and release sites the presence of insect neurohormones whose structure has been elucidated. Moreover, the presence of vertebrate and invertebrate neuropeptides has been demonstrated in insects. As regards biogenic amines, methods of detection have been greatly refined and it is now possible to identify the cell bodies and axons of the main biogenic amines. Other new methods, such as cobalt chloride impregnation or Lucifer yellow staining, have revealed the axonal pathways and the location of particular neurons. The mechanisms of action of neurohormones have been investigated in several cases and the results of these investigations will be related in the chapters which follow.

1 Synthesis and Release Sites of Neurohormones.- 1.1. From the Original Concept of Neurosecretion to Contemporary Views.- 1.1.1. The Concept of Neurosecretion.- 1.1.2. The Blood Pathway -Neurohemal Organs.- 1.1.3. Developmental Phase of the Investigations.- 1.1.4. New Problems.- 1.1.5. The Neuroeffector Junctions.- 1.1.6. Nonconventional Neurosecretory Cells.- 1.1.7. Aminergic Neurosecretory Cells.- 1.1.8. Endorphins.- 1.1.9. Characterization of Peptidergic Neurohormones.- 1.1.10. Extensive Localization of Neuropeptides.- 1.1.11. Colocalization.- 1.1.12. Neuromodulation.- 1.1.13. Regulation of Peptidergic Neuron Activity.- 1.1.14. Conclusion.- 1.2. Classical Insect Neurosecretory Cells.- 1.2.1. General Features 1.- 1.2.2. Neurosecretory Cell Diversity.- 1.2.3. Anatomy of the Neurosecretory System.- 1.3. Neurosecretory Pathways.- 1.3.1. Neuropil Arborization of Brain Neurosecretory Cells.- 1.3.2. Pathways to the Corpora Cardiaca and Corpora Allata.- 1.3.3. Pathways to the Prothoracic Gland.- 1.3.4. Pathways in the Central Nervous System.- 1. 4. Release Sites.- 1.4.1. The Corpora Cardiaca.- 1.4.2. Perisympathetic Organs.- 1.4.3. Neurohemal Areas.- 1.4.4. Neuroeffector Junctions.- 1.4.5. Embryonic Formation of Perisympathetic Neurohemal Areas.- 1.4.6. Discussion.- 1.5. Regulation of Neurohormone Production and Release.- 1.5.1. Environmental Factors.- 1.5.2. Internal Factors.- 1.5.3. Circadian Activity-Autoregulation.- 1.5.4. Neurosecretory Cell Interrelationships.- 1.5.5. Substances Involved.- 1.5.6. Control of the Release of Neurosecretory Products.- 1.5.7. Hormonal Feedback.- 1.6. Aminergic Neurons.- 1.6.1. Methods.- 1.6.2. Occurrence in the Central Nervous System.- 1.6.3. Quantitative Determinations.- 1.6.4. Distribution in Central Nervous System.- 1.6.5. Sympathetic Nervous System.- 1.6.6. Corpora Cardiaca.- 1.6.7. Perisympathetic Organs.- 1.6.8. Serotonergic Networks.- 1.6.9. Mode of Action.- 1.6.10. Conclusion.- 1.7. Concluding Remarks.- 2 Vertebrate and Invertebrate Neuropeptides in Insects.- 2.1. Insect Neurons Immunoreactive to Vertebrate Peptide Antisera.- 2.1.1. Neurophysins-Vasopressin-Oxytocin.- 2.1.2. Opioids and Related Molecules.- 2.1.3. Gastroenteropancreatic Peptides.- 2.1.4. Miscellaneous.- 2.2. Insect Neurons Immunoreactive to Invertebrate Neurohormones.- 2.3. Insect Neurons Immunoreactive to Insect Neurohormones.- 2.3.1. Proctolin.- 2.3.2. Adipokinetic Hormone.- 2.3.3. Eclosion Hormone.- 2.3.4. Neuroparsins A and B.- 2.4. Distribution of Immunoreactive Products.- 2.4.1. Nervous and Neuroendocrine System.- 2.4.2. Midgut.- 2.5. Immunoreactive Neurons and Neurosecretory Cells.- 2.6. Cross-Reactions-Colocation of Immunoreactive Peptides.- 2.7. Concluding Remarks.- 3 Control of Prothoracic Gland Activity.- 3.1. Prothoracic Gland Innervation and Ultrastructure.- 3.1.1. Prothoracic Gland Innervation.- 3.1.2. Perisympathetic Organs.- 3.1.3. Origin Cells.- 3.1.4. Prothoracic Gland Structure-Variations.- 3.1.5. Ultrastructural Data.- 3.1.6. Ultrastructural and Immunocytochemical Data.- 3.2. Prothoracic Gland Degeneration.- 3.3. PTTH Assays.- 3.3.1. In Vivo Assays.- 3.3.2. In Vitro Assays.- 3.4. Timing of PTTH Release.- 3.4.1. Hyalophora.- 3.4.2. Manduca.- 3.4.3. Bombyx.- 3.4.4. Galleria and Ephestia.- 3.4.5. Rhodnius.- 3.4.6. Concluding Remarks.- 3.5. PTTH Production and Release Sites.- 3.5.1. Production Sites.- 3.5.2. Release Sites.- 3.6. Purification of PTTH.- 3.6.1. Bombyx PTTH.- 3.6.2. Manduca PTTH.- 3.6.3. Embryonic PTTH.- 3.6.4. EDNH versus PTTH.- 3.6.5. Interspecific Activity of PTTH.- 3.7. PTTH Action Mechanism.- 3.8. Is PG Regulated by Factors Other Than PTTH?.- 3.8.1. Ventral Nerve Cord.- 3.8.2. Nerve Connections.- 3.8.3. Ecdysone and 20-HE feedback.- 3.8.4. Juvenile Hormone Feedback.- 3.8.5. Hemolymph Stimulatory Factor.- 3.8.6. Prothoracic Gland Activation in Debrained Insects.- 3.9. Conclusion.- 4 Regulation of Corpora Allata Activity and Juvenile Hormone Titer.- 4.1. Juvenile Hormones, Their Esterases and Binding Proteins.- 4.1.1. Juvenile Hormone Molecular Structure.- 4.1.2. Juvenile Hormone Titer.- 4.1.3. Juvenile Hormone Esterases.- 4.1.4. Juvenile Hormone-Binding Proteins.- 4.1.5. Juvenile Hormone Analogs.- 4.1.6. Precocene-Azadirachtin-Antibodies.- 4.2. Juvenile Hormone Assays.- 4.2.1. Physicochemical Determination.- 4.2.2. Radioimmunoassay.- 4.2.3. Short-term Radiochemical in Vitro Assay.- 4.3. Corpora Allata Innervation and Structure.- 4.3.1. Corpora Allata Innervation.- 4.3.2. Structure and Ultrastructure.- 4.4. Neurohormonal versus Nervous Regulation.- 4.4.1. Cockroaches.- 4.4.2. Locusts and Other Orthopterans.- 4.4.3. Anisolabis and Labidura.- 4.4.4. Leptinotarsa.- 4.4.5. Moths.- 4.4.6. Bugs.- 4.5. Purification of Allatotropins.- 4.6. Recapitulation.- 4.6.1. Nervous Regulation.- 4.6.2. Allatotropins and Allatostatins.- 4.6.3. Role of the Ovary.- 4.6.4. Ecdysone and 20-HE.- 4.6.5. Juvenile Hormone.- 4.6.6. Esterase Regulation.- 4.7. Conclusions.- 5 Diapause.- 5.1. Imaginal Diapause.- 5.2. Pupal Diapause.- 5.3. Larval Diapause.- 5.4. Embryonic Diapause.- 5.5. Purification of the Embryonic Diapause Factor.- 5.6. Conclusions.- 6 Reproduction.- 6.1. Sex Determination.- 6.1.1. Lampyris.- 6.1.2. Leptinotarsa.- 6.2. Oogenesis.- 6.2.1. Oogenesis: First Steps.- 6.2.2. Ovariole Differentiation.- 6.2.3. Previtellogenesis.- 6.2.4. Vitellogenesis.- 6.2.5. Chorionization.- 6.2.6. Vitellogenesis and Vitellogenin Synthesis in the Male.- 6.2.7. Concluding Remarks.- 6.3. Spermatogenesis.- 6.3.1. Ecdysone.- 6.3.2. Macromolecular Factor.- 6.3.3. Juvenile Hormone.- 6.3.4. Neurohormones.- 6.3.5. Concluding Remarks.- 6.4. Accessory Glands.- 6.4. l. Morphogenesis of Accessory Glands and Ducts.- 6.4.2. Physiological Role of Accessory Glands.- 6.4.3. Accessory Gland Regulation.- 6.5. Mating.- 6.5.1. Cockroaches.- 6.5.2. Locusts and Crickets.- 6.5.3. Beetles.- 6.5.4. Lepidopterans.- 6.5.5. Dipterans.- 6.5.6. Bugs.- 6.5.7. Conclusion.- 6.6. Ovulation-Oviposition-Parturition.- 6.6.1. Overall Cephalic Control.- 6.6.2. Role of the Last Abdominal Ganglion.- 6.6.3. Neurohormones.- 6.6.4. Production Sites of the Neurohormones.- 6.6.5. Neurohormone Release Sites.- 6.6.6. Interspecificity of the Neurohormonal Factors.- 6.6.7. Proctolin and Other Myotropic Peptides.- 6.6.8. Biogenic Amines.- 6.6.9. Juvenile Hormone and Ecdysone.- 6.6.10. Mode of Action of the Neurohormones.- 6.7. Particular Modes of Reproduction.- 6.7.1. Social insects.- 6.7.2. …