abnormal sperm migration in female genital tract +
any anomaly in the ability of ejaculated sperm to migrate through the female genital tract to reach the oocyte in the oviduct; during their transit in the female tract, sperm encounter different environments with various mechanical and biochemical properties; to complete the journey, each sperm has to swim in a highly viscous medium in the cervix, avoid immunological detection in the uterus, cross the uterotubal junction, and ascend into the oviduct isthmus to ultimately reach the site of fertilization, the ampullary region of the oviduct