Connective Tissues, phylogenetic considerations, origin of its concept, its progression from anatomy to cell and molecular biology
The « tissue » concept was among the first important generalization – a metaphor – in medical-scientific literature. Metaphors always plaid an important role in the progress of Biology as stated by Evelyn Fox-Keller, epistemologist of Sciences at MIT . It appears in the French medical literature, at least during the XVIIIth Century, as for intance in the tretease on chronic diseases by the Bordeu-s, a family of outsanding physicians in the Bearn Country, the south-west of France . The Tissue concept found its full blown expansion in Medicine with the work of Xavier Bichat (1771-1802), used however before him, by the last attending physician of Queen Marie Antoinette, Felix Vicq d’Azyr (1748-1794). Bichat distinguished 22 sorts of Tissues, a restricted selection of these composing the organs, the only visible components of the body, as seen by the early anatomists [4, 5]. The macromolecular constituents of the « tissue cellulaire » as called in the French texts started to be recognized first by histological procedures from the last decades of the XIXth Century, followed by their isolation and characterization all through the XXth Century. Even in the 1950ies, when we started our experiments at the Paris Medical Faculty, the number of these constituents remained restricted to 3, collagen, elastin and acid mucopolysaccharides. « Tissue cellulaire » was progressively replaced by « subtance fondamentale » (ground substance), followed by Connective Tissues and Extracellular Matrix.
The phylogenetic origin of these tissues was also clarified dring the last Century. The « fibroblasts » appeared recognizably with Trichoplax adherens, a plaquozoan, close to but simpler than the sponges which exhibit several macromolecular components of connective tissues: collagens, fibronectin,with cell-matrix interactions [6, 7]. During the second half of the XXth Century a large number of macromolecular constituents of the extracellular matrix were identified, belonging to four major clases, collagens, elastins, glycosaminoglycans – proteoglycans and structural or matrix glycoproteins. With the intense study of fibronectin started the ever increasing recognition of the dynamic nature of cell matrix interactions mediated by receptors, integrins, the elastin receptor and others. Progress in molecular genetics enables now teams specialized in this discipline to complete the description of connective tissues by the identification of sequential gene activation « programs » resulting in the fine tuning of macromolecular tissue composition and fonction. Started also during the last decades, the study at the molecular – genetic level of pathological modifications of connective tissues and more recently their age-related alterations , as seen for instance in malignant growth . No doubt that in the coming decades, the molecular and genetic regulations of connective tissue structure and fonctions will continue to make progresses.. From an essentially medical science it became a « basic discipline » with however constant cross-talk between « basic » and medical scientists. In these respect, our Society, as also those of other countries will continue to play a crucial role by bringing together scientists of subspecialities as for instance the Meetings of the Gordon Conferences, or those of the Federation of European Connective Tissue Societies (FECTS), founded also in Paris in 1967, to exchange, discuss and refine emerging concepts. To finish I wish to thank my friends, colleagues and my close family, my wife Jacqueline and my brother Alexandre who helped so much to transform into a living reality my dreams which emerged during my stay at the Biochemical Deprtment and Eye Institute of Columbia University, New York City, in 1961. My gratitude goes also to my friend, Prof. Y. Pouliquen, President of the Singer Polignac Foundation who generously helped us to orrganize this celebration.
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