Endogenous Substances Affecting the Myometrium

the point very well: there are synchronous and synchronized cultures. The former refers to a culture of cells at a similar stage in their life cycle as a result of selection, usually by size, from a heterogeneous population. A synchronized culture consists of cells whose life cycles are chronologically aligned because of some inducing stress, such as alternating periods of light and dark (for a photosynthetic organism) or a period of inhibition of some process like DNA synthesis which is necessary for cell division. (It was, not surprisingly, Arthur Pardee who first saw the significance of the difference between these two methods). Both synchronous and synchronized cultures are valuable to study, but it is extremely important to maintain the distinction between them, so as to avoid confusing normal metabolic changes with artifacts of the synchronizing stress. An example of such an artifact is provided by the results of Cook on light-synchronized Euglena, in which the onset of the light period probably precipitates the immediate replication of chloroplast DNA, a phenomenon unrelated to the age of the cell. While the authors in this book who use synchronized cells have in general been alert to the possibilities of misinterpretation, the distinction between synchronous and synchronized cultures must be borne in mind in evaluating any experiments involving cell synchrony. The various organisms studied in Cell Synchrony range from the ubiquitous E. coli through the myxomycete Physarum polycephalum to the diatoms Cylindrotheca fusiforma and Nazicula pelliculosa. There are numerous examples of both methods of achieving synchrony. One could wish that some of the authors would bring to the design of their experiments the amount of originality they showed in choosing their systems, but the overall quality of the work reported is high and the book provides ready access to a cross-section of one of the most exciting fields of cell biology. This edition surveys the current status and direction of investigation concerning a variety of endogenously produced substances affecting smooth muscle. Particular emphasis is given to the influence of these agents on myometrial activity. It records the proceedings of a symposium held in Bristol, England in July 1965. As is typical of the memoirs, the participants comprise an international roster of experts actively engaged in this field of research. The variety of myometrial activators discussed include polypeptides (oxytocin and derivatives), steroids, postaglandins, catecholamines, parasymphathomimetic agents, histamine, simple cations and their interactions. Part one is …