The transparent sea urchin embryo provides a laboratory for study of morphogenesis. The calcareous endoskeleton is formed by a syncytium of mesenchyme cells in the blastocoel. The locations of mesenchyme in the blastocoel, the size of the skeleton, and even the branching pattern of the skeletal rods, are governed by interactions with the blastula wall. Now Guss and Ettensohn(1) show that the rate of deposition of CaCO3 in the skeleton is locally controlled in the mesenchymal syncytium, as is the pattern (...) of expression of three genes involved in skeleton formation. They propose that short range signals emanating from the blastula wall regulate many aspects of the biomineralization process. (shrink)

Health technology assessment consists of thesystematic study of the consequences of theintroduction or continued use of the technology in aparticular context, with the explicit objective toarrive at a judgment of the value or merit of thetechnology. Ideally, it is aimed at assessing allaspects of a given technology or group oftechnologies, including non-technical, e.g.socio-ethical, aspects. However, methods for assessingsocio-ethical implications of health technology arerelatively undeveloped and few mechanisms exist totake action based on the results of such evaluations.Still, the examples of cochlear (...) inplants and other cases illustratethat HTA is not a matter of merely collecting thefacts about a technology. The facts must beplausible and relevant from a particular framework,which is not always shared by different groups. It ishere that socio-ethical aspects are encountered. Ifhealth technology assessment aims to enhance theaccountability of the decision making processregarding funding and use of health technology, it isa major challenge to assessors of health technologiesto deal adequately with existing value pluralism. Inthis respect interactive evaluation may have somethingto offer. (shrink)

Classical embryological studies have provided a great deal of information on the autonomy and stability of cell fate determination in early sea urchin embryos. However, these studies were limited by the tools available at the time, and the interpretation of the results of these experiments was limited by the lack of information available at the molecular level. Recent studies which have re‐examined classical experiments at the molecular level have provided important new insights into the mechanism of determination in sea urchins, (...) and require us to re‐evaluate some long standing theories on the process of differentiation. (shrink)

Battles, Betrayals, and Brotherhood: Early Chinese Plays on the Three Kingdoms. Edited and trans lated, with an introduction by Wilt L. Idema and Stephen H. West. Indianapolis: Hackett Publishing Company, 2012. Pp. xxx + 469. $78, $28, $23.95.