To localize the different proteins involved in the executioner step of apoptosis in the human testicular tissue: effector caspases (3, 6, and 7), caspase inhibitors called inhibitor of apoptosis proteins (IAPs, such as XIAP), and IAP inhibitors such as Smac/DIABLO and to investigate XIAP and Smac expression and activation of caspase-3 in azoospermia.