Knowledge in the field of the biology of the extracellular matrix, and in particular of collagen, has made considerable progress over the last ten years, especially in mammals, birds and ln man with respect to very important applied medical aspects. Basic knowledge in the animal kingdom overall has increased more slowly and haphazardly. We, therefore, considered it useful to organize a meeting specifically devoted to the study of the invertebrate and lower vertebrate collagens. The NATO Scientific Division financed an Advanced Research Workshop aimed at bringing together experts qualified in collagen biology (with morphological, biochemical and genetic specialization) with researchers who are currently studying collagenous tissues of invertebrates and lower vertebrates. The Medical-Biology Committee of the CNR-Rome and the University of Milan also supplied interest and support for the organization of this Meeting. The format of the workshop consisted in: 1) main lectures on the most recent aspects of collagen biology; 2) minireviews on the current knowledge of collagenous tissues in the various invertebrate phyla and in fish; 3) contributed papers on particular aspects of research in specific fields; 4) workshops on the methodology of studying collagen. As we had intended, the Workshop gave a comprehensive overview of acquired knowledge and of the present state of research actlvlty. It permitted wide interdisciplinary discussion, enabling collabora­ tions to be established and new research themes to be chosen. This volume contains the text of all the contributions presented at the Meeting, including posters.

I: Introduction.- Invertebrate Collagens in the Scheme of Things.- Collagen and Animal Phylogeny.- II: General Data on Collagen Biochemistry Molecular Assembly and Interactions.- Collagen Families - Evolutionary Adaptations of Molecular and Macromolecular Structures to Physiological Functions.- The Different Types of Collagen Present in Cartilaginous Tissues.- Collagen Cross-Linking.- Structure of Collagen Fibrils.- Role of Collagenous and Non-Collagenous Components in Biological Calcification.- Mediation of Cell Matrix Interactions by Collagen and Laminin Binding Cell Surface Proteins.- Metazoan Mesenchyme Partitions the Extracellular Space during Matrix Morphogenesis.- Spatial Organization of Collagen Fibrils in Skeletal Tissues: Analogies with Liquid Crystals.- Collagen Gene Structure.- III: Invertebrate and Lower Vertebrate Collagens.- Porifera.- The Collagen of the Porifera.- Sponge Gemmule Coats: Germanium Modification of a Collagenous Structure.- Two Distinct Populations of Collagen Fibrils in a "Sclerosponge".- The Role of Sponge Collagens in the Diet of the Hawksbill Turtle (Eretmochelys imbricata).- Coelenterata.- Collagen of Coelenterates.- The Collagenous Component of Veretilium cynomorium (Cnidaria).- Achelminthes.- The Collagen of Aschelminthes.- Ultrastructural Study of the Connective Tissues of Parascaris equorum.- Annelida.- The Collagens of the Annelida.- The Interstitial Collagen of Lumbricus sp. (Annelida).- Long Pitch Helices in Invertebrate Collagens.- Similarity between Earthworm Cuticle Collagen and the Chemoattractant for Garter Snakes Solubilized from the Exterior Surface of Earthworms.- Mollusca.- The Collagen of the Mollusca.- The Role of Collagen in the Mechanical Design of Squid Mantle.- The Sclerotization of the Collagenous ByssalThreads of Mytilus edulis L..- Ultrastructural and Biochemical Study on Collagen from the Neural Sheath of Sepia officinalis.- Comparative Ultrastructural Analysis on the Connective Tissue Organization of Neural Sheaths in Mollusca.- Quantitative Analysis on the Distribution of Collagen Fibril Diameters in the Neural Sheath of Sepia officinalis.- A Collagen Analogue System in Nucella lapillus (Prosobranchia, Stenoglossa).- Crosslinking and Chemical Characterization of Cephalopod Collagens.- Arthropoda.- The Collagen of the Arthropoda.- Echinodermata.- The Collagen of the Echinodermata.- Graptolites.- The Fine Structure of Graptolite Periderms.- Fishes.- The Interstitial Collagens of the Fishes.- The Selachian Egg Case Collagen.- Elastoidin.- Comparative Fine Structure of the Actinotrichia (Elastoidin) in Developing Teleost and Dipnoi Fish Fins.- Collagen and Mineralization in the Elasmoid Scales.- The Deep Scleroblast of the Regenerating Teleost Scale: a Model of Cell Producing a Collagenic Plywood.- Nidamental Gland Secreting the Dog-Figh Egg-Shell.- IV: Workshops on the Methodological Problems in the Analyses of Invertebrate and Lower Vertebrate Collagens.- Methods of Extraction, Purification and Reprecipitation.- Collagen immunotyping.- The Banding Pattern of Collagen.- Dielectric Spectroscopy in Collagen.- V: Conclusions.- Evolution and Collagen.- Concluding Remarks.- Participants.- Systematic Index.