While discussing how the grounded theory mediod has been situated during the five moments of qualitative research history, a detailed analysis is offered of die differences between the classic mode of die mediod and Strauss and Corbin's reformulation of the mediod. Such differences include: philosophical perspectives, paradigm of inquiry, intended product, dieoretical underpinnings, procedural steps and claims of rigour. Reasons for Strauss. and Corbin's elaboration of the mediod are suggested, widiin an historical context.

How cell commitment and differentiation are controlled in the early stages of embryogenesis is a problem that has long fascinated developmental biologists. Retinoic acidinduced differentiation of embryonal carcinoma cells in culture provides a model in which these questions can be explored. Recent work has yielded exciting insights into the central series of molecular changes which drives the commitment of these cells to formation of a new phenotype. Interacting with the key molecules in this central pathway is a variety of transcription (...) factors, many of which show changes in availability and/or activity during differentiation. In various combinations, these modulate the activities of genes involved in both cell proliferation and in the production of extracellular matrix and other proteins characteristic of differentiated cells. (shrink)