VARYING DEVELOPMENTAL MECHANISMS IN TERATOLOGY

[摘要] The great variety of developmental mechanisms which may be involved in the genesis of abnormalities is emphasized. The following examples are presented: Too little growth; too little resorption; too much resorption; a resorptive process normal in character but occurring in an abnormal location; a growth process normal in character but occurring in an abnormal location and, finally, too much growth of some particular structure or tissue. With this variety of developmental mechanisms involved, the futility of expecting to find any blanket cause of congenital defects should be self-evident. Moreover, one would not expect to find the various causative factors even in the same category.See figure in the PDF.fileIn cases of too little growth, i.e., cases of the "developmental arrest" type, one would naturally look for deficiency factors, or for inhibiting factors-genetic or environmental.In the case of too much or too little resorption as a secondary moulding process, or with growth or resorptive processes out of their normal territory, one would look for regulatory factors. So, also, with disturbances in timing, which were not discussed but which I believe we will find of great importance when we know more accurately the rate at which critical developmental process should normally progress.See figure in the PDF.fileFinally, especial emphasis is placed on defects involving the overproduction of a tissue, or a structure, because the factors which might cause overgrowth must be of a different nature than the inhibiting or deficiency factors we have so long been accustomed to emphasize.See figure in the PDF.fileI feel certain that in other papers in this conference there will be stressing of the multiplicity of etiologic factors, as well as similar emphasis on the variety of developmental mechanisms involved. I believe that we shall gain the conviction that each type of defect and each possible etiologic factor must be intensively studied on an individual basis if we are to make sound progress instead of bogging down in a morass of vague generalizations.

[学科分类] 儿科学