Waldby and Mitchell pull together a prodigious amount of research-involving policy reports and scientific papers, operating manuals, legal decisions, interviews, journalism, and Congressional testimony-to offer a series of case studies based on particular forms of tissue exchange. They examine the effect of threats of contamination-from HIV and other pathogens-on blood banks' understandings of the gift/commodity relationship; the growth of autologous economies, in which individuals bank their tissues for their own use; the creation of the United Kingdom's Stem Cell bank, which facilitates the donation of embryos for stem cell development; and the legal and financial repercussions of designating some tissues "hospital waste." They also consider the impact of different models of biotechnology patents on tissue economies and the relationship between experimental therapies to regenerate damaged or degenerated tissues and calls for a legal, for-profit market in organs. Ultimately, Waldby and Mitchell conclude that scientific technologies, the globalization of tissue exchange, and recent anthropological, sociological, and legal thinking have blurred any strict line separating donations from the incursion of market values into tissue economies.