Effect of Oxygen Levels in Villous Trophoblast Apoptosis

In pregnancies complicated by intrauterine growth restriction (IUGR), the villous trophoblast shows increased apoptosis and immature cytotrophoblasts (CT) may be exposed to both higher or lower oxygen levels than normal placentae. We propose that villous CT undergo higher frequencies of apoptosis at extreme oxygen tensions. The apoptosis of CT isolated from normal term placentae was examined before culture and after 24 h of culture at different oxygen tensions with or without TNFα. The apoptosis frequencies of cells cultured for 24 h at O 2levels of ∼15 mm and ∼38 mm Hg were similar to the frequency before culture. Both constitutive and TNFα-induced apoptosis and cell loss were highest at low (