Molecular Reproduction & Development Volume 78, Issue 9 cover image

Failure of embryos to develop in vitro is often associated with increased cellular death or apoptosis. Apoptotic cell death signals involve the activation of cysteine proteases, namely caspases, which are produced as catalytically inactive zymogens and must undergo proteolytic processing (cleavage) for activation. Coutinho et al. (this issue) fi nd that cleaved (active) caspase 3 (CC3) was detected (green staining) in porcine embryos, and that elevated levels predict cell death and developmental delay. Blue staining indicates cell nuclei.