['To determine if sperm attachment to oviduct epithelial cells (OEC) in vitro is selective for higher quality sperm and if the system requires homologous species OEC.', 'Controlled prospective study with outcomes assayed by a technician blind to sperm treatment groups.', 'An academic research laboratory.', 'Experiment 1: normospermic donors with children (4 donors, 7 ejaculates). Experiment 2: cryopreserved donor samples (4 donors).', 'Semen collection by masturbation after 48 hours of abstinence.', 'Experiment 1: sperm assays of motility, morphology, membrane integrity, and capacitation status. Experiment 2: sperm chromatin (DNA) integrity and condensation.', 'Experiment 1: sperm not attaching to OEC had lower motility, more membrane disruptions, and more acrosome reactions than did control sperm. This selectivity was equivalent for sperm in coculture with all OEC types. Experiment 2: sperm attached to OEC had fewer abnormalities in chromatin structure compared with sperm that were not attached.'] Do higher-quality human sperm in a sample selectively attach to oviduct ( fallopian tube ) epithelial cells in vitro?