The creation and use of transpecies human-animal embryos for research has figured prominently in recent highly controversial changes to UK reproductive legislation. This article reflects on the debate in the UK parliamentary context, drawing on socio-anthropological writing on hybridity. It seeks to make sense of two related cultural contradictions evident in the debate. First, a paradoxical position has been taken over decades in which the law simultaneously bans and yet permits the production of transpecies embryos. Second, key stakeholders have based their arguments on the simultaneous differentiation and dedifferentiation of embryos. Attempts to distinguish between different classes of embryo (cybrids, chimeras, pure hybrids, etc.) have been in tension with pressures to homogenize all embryos as morally equal. The article explores both of these contradictory tensions in the debate and their significance for the regulation and oversight of reproductive research.

This article explores the changing expectations and contested identity of blood stem cells (haematopoietic stem cells or HSCs). While much social science critique has of late been focused on embryonic stem cells, relatively little attention has been given to the historical emergence of stem cell biology, especially the importance of blood innovation stretching back through the middle of the twentieth century and beyond. Present-day stem cell networks inherit much from the historical engagement of medical technology with blood, especially in the contexts of blood processing, bone marrow transplantation and, more recently, gene therapy. In making sense of the shaping of blood stem cells this article draws on perspectives in the ‘sociology of expectations’ in exploring the way current expectations of stem cells are historically constituted. In this way we examine the way biological entities—HSCs in this case—become the focus and bearers of future value in contemporary global stem cell economies.