Effect of serum from patients with minimal to mild endometriosis on mouse embryo development in vitro.
 Two-cell mouse embryos were cultured at 37 degrees C in 5% CO2, 95% air with a 7.5% serum supplement from patients with minimal to mild endometriosis, (group I, n = 31), tubal factor (group II, n = 33), male factor (group III, n = 17), fetal cord samples (group IV, n = 37), and Ham's F-10 medium (Gibco, Grand Island, NY) without a serum supplement (group V, n = 30).
 The progression to blastocyst stage (mean percent +/- SE) at 96 hours in groups I, II, III, IV, and V was 29.9% +/- 3.7%, 60.6% +/- 4.9%, 56.2% +/- 5.2%, 61.7% +/- 5.8%, and 63.2% +/- 6.9%, respectively.
 Serum factors appear to be associated with an inhibition of early embryogenesis, which may explain the decreased fertility rates observed in patients with minimal to mild endometriosis.
