Effects of temperature on in vitro penetration of human sperm into bovine cervical mucus

A standardized bovine cervical mucus preparation was used to test the hypothesis that the penetration of human sperm into cervical mucus is a temperature-dependent process. Cervical mucus penetration (CMP) was tested in vitro at several incubation temperatures around "room" temperature. Semen specimens were also exposed to cold (0 C) for various periods of time and then tested for CMP at 37 C incubation. We found that incubation at 37 C produced optimal sperm-mucus penetration. Minor fluctuations in ambient laboratory temperature, such as may occur during a workday or between seasons, produced significant variations in CMP results and precluded the comparison of test results longitudinally over time. Prior exposure of normal semen specimens to 0 C for as long as 45 minutes, such as might occur in transport, did not reduce CMP significantly if incubation was performed at 37 C. We conclude that 37 C is the optimal incubation temperature for CMP testing and that if temperature is controlled, CMP is sufficiently simple and reproducible for routine use in physicians' offices and clinical laboratories.