ABSTRACT
By request of the committee which organized the conference on ‘The Cellular Basis of Differentiation’, I undertook to open the meeting with a sort of topical outline that might serve as a guide in the subsequent free and informal discussion. In view of the diverse meanings attached to the term ‘differentiation’ in various quarters, from development in general in the broadest sense to the production of visible specialized cell structures in the narrowest sense, it seemed desirable to circumscribe at least the scope within which the conference was to hold itself. The instructions of the organizing group were to focus the discussion on the cellular transformations which lead to the final functional state of the mature cell. This limitation is taken into account in the following outline. At the same time it is clear that terminal cell specialization is part of a continuous process, hence cannot be neatly separated from antecedent developmental processes leading up to it. Therefore the difference between this presentation and others dealing with early embryonic phases lies in the emphasis rather than in the nature of the objects. In fact, it is becoming ever more evident that the study of special histogenesis and organogenesis may cast as much light on the interpretation of early embryonic processes as the study of early events, e.g. the formation of the fertilization membrane or of the sperm tail, contributes to the understanding of specific terminal cytodifferentiation. Accordingly, the main objective of the following outline is to set the problem of cellular differentiation into proper focus and perspective within the broad problems of ontogeny.
