Aging and Cell Structure : Volume 1

Approaching any task on aging brings a flood of images that are a personal repetition of what has been one of the greatest and most persistent concerns of mankind. Even restricting time to the past decade or so and approaching only the biomedical sciences, one still encounters a flood of information in this relatively young research area. The­ ories and ideas abound as though each researcher provides one of his own. This might well be expected; aging is an exceedingly complicated series of crossroads involving trails and even superhighways. Each specialist has a peephole (society, body, organ, tissue, cell, or-especially in modern biology-cellular organelles, macromolecules, and even molecules) and the views of the crossroads are obviously different. Hence, the num­ ber of observations just about equals the number of independent ideas put forward. It is natural to seek from highly specialized knowledge a fundamental understand­ ing of aging through the modern research trends in biology that focus on events at the cellular, subcellular, macromolecular, and molecular levels. The ultimate clues must lie there-with one serious complication: There are numerous cell types in any body and each cell type is a very complex machine of its own. Additionally, there are potential repercussions in that different cells, tissues, and even molecules have effects on one another. This is indeed a confusing situation, and one for which we must seek reliable answers, provided that we can take a step back and provide a generalized view.

1. Central Nervous System.- 1. Introduction.- 2. Dendritic Changes.- 3. Loss of Neurons.- 4. Changes in Dendritic Spines.- 5. Changes in Synaptic Populations.- 6. Changes in Cell Body and Nuclear Sizes.- 7. Changes in Nucleoplasm.- 8. Changes in Neuronal Cytoplasm.- 9. Neurofibrillary Tangles.- 10. Lipofuscin.- 11. Neuroglia.- 12. Choroid Plexus.- References.- 2. The Mammalian Peripheral Nervous System in Old Age.- 1. Introduction.- 2. Age-Related Changes in Man.- 2.1. General Comments.- 2.2. The Aging Sensory Unit.- 2.3. The Aging Motor Unit.- 2.4. The Aging Peripheral Autonomic System.- 2.5. The Aging Peripheral Nerve of Man.- 3. Age-Related Changes in Animals.- 3.1. General Comments.- 3.2. The Aging Sensory Unit.- 3.3. The Aging Motor Unit.- 3.4. The Aging Peripheral Autonomic System.- 3.5. The Aging Peripheral Nerve of Laboratory Animals.- 4. Concluding Remarks.- 4.1. Lipofuscin.- 4.2. Central-Peripheral Distal Axonopathy.- 4.3. Proximal Demyelination.- 4.4. Neuronal Loss.- 4.5. Epilogue.- References.- 3. Neurofibrillary and Synaptic Pathology in the Aged Brain.- 1. Age-Associated Changes in the Human Brain.- 2. Neurofibrillary Pathology.- 2.1. Normal Fibrillar Proteins in the CNS.- 2.2. Neurofibrillary Changes.- 2.3. Experimentally Induced and Naturally Occurring Neurofibrillary Changes.- 3. Synaptic Pathology and Glial Reactions.- 3.1. Morphology of the Neuritic Plaque.- 3.2. Pathogenesis of the Neuritic Plaque.- 3.3. Morphology of the Neuritic Changes.- 3.4. Role of Microglial Cells in Amyloid Deposition.- 3.5. Relationships between Amyloid Fibrils and PHFs.- References.- 4. Cytomorphological Alterations in the Aging Animal Brain with Emphasis on Golgi Studies.- 1. Introduction.- 1.1. The Use of Animal Models in Aging Research.- 1.2. Memory Deficits in Aging Animals.- 1.3. Neuronal Loss in Aging.- 2. The Aging Brain: A Golgi Perspective.- 2.1. The Dendritic Tree and Its Spines.- 2.2. A Survey of Golgi-Impregnated Neuronal Changes in the Aging Cerebral Cortex.- 2.3. Age-Related Alterations in the Cerebellum—Purkinje Cells.- 2.4. Golgi Studies of Dendritic Plasticity in the Adult and Aged Brain.- 3. Electron Microscopy of the Aging Brain.- 3.1. Lipofuscin.- 3.2. Nuclear Membrane Infolding.- 3.3. Filamentous Accumulation.- 3.4. Corpora Amylacea.- 3.5. Synaptic Alterations.- 3.6. Tubulovesicular Profiles.- 3.7. Alterations in Myelinated Fibers.- 4. Discussion.- 4.1. Golgi Studies.- 4.2. Electron Microscopy—Structural Changes in Aging Animal Brain.- 5. Summary and Conclusions.- References.- 5. Variation: Principles and Applications in the Study of Cell Structure and Aging.- 1. Origin of Variation.- 2. Analysis of Variation.- 3. Variation and Aging.- 4. Applications.- 4.1. Variation in Mouse Liver Cellular and Fine Structure: Effects of Aging, Alcohol, and Antioxidants.- 4.2. Variation in Vitality and Mortality.- 4.3. Time-Condensing in Experimental Aging Research through the Study of Variation.- 5. Concluding Remarks.- References.- 6. Ultrastructure of the Aging Kidney.- 1. Introduction.- 2. Materials and Methods.- 2.1. Rats.- 2.2. Humans.- 2.3. Ultrastructural Studies.- 3. Results.- 3.1. Rat Ultrastructural Studies.- 3.2. Clinicopathologic Correlations.- 4. Discussion.- References.- 7. Electron Microscopy of Skeletal Aging.- 1. Introduction.- 2. Bone 252.- 2.1. Periosteum.- 2.2. Endosteum.- 2.3. Osteocytes.- 2.4. Osteoclasts.- 2.5. Bone Surfaces.- 3. Cartilage.- 3.1. General Cartilage Aging.- 3.2. Electron Microscopy of Aging Cartilage.- 4. Summary and Conclusions.- References.- 8. The Cardiovascular System.- 1. Introduction.- 2. The Effect of Age on Physiological Parameters of the Cardiovascular System.- 2.1. Heart Rate and Electrocardiogram.- 2.2. Blood Pressure.- 2.3. Cardiac Output and Stroke Volume.- 2.4. Contractile Properties.- 2.5. Decline of Physical Work Capacity.- 3. The Effect of Age on the Structure of the Myocardium.- 3.1. Connective Tissue.- 3.2. Myocardial Cell.- 4. The Effect of Age on Coronary Vessels.- 5. The Effect of Age on the Reactivity of the Cardiovascular System to Drugs.- 5.1. Age-Associated Changes in Pharmacokinetics of Drugs.- 5.2. Digitalis Glycosides.- 5.3. Autonomic Drugs.- 5.4. Antiarrhythmic Agents.- 6. Summary.- References.- 9. Fine Structure of Aging Skeletal Muscle.- 1. Introduction.- 2. Structural Changes in Human Muscle.- 3. Freeze-Fracture Studies.- References.- 10. Insect vs. Mammalian Aging.- 1. Introduction.- 2. Comparison of Tissue and Body Organization in Insects and Mammals.- 3. Fine Structural Manifestations of Aging.- 3.1. Age Pigment.- 3.2. Mitochondria.- 3.3. Ribosomes, Endoplasmic Reticulum Membranes, and RNA.- 3.4. Nuclei.- 4. Comparison between Insect and Mammalian Aging.- 5. Conclusions.- References.