Dead spermatozoa in raw semen samples impair in vitro fertilization outcomes of frozen-thawed spermatozoa

摘要

Objective: To evaluate the influence of dead spermatozoa present in raw semen samples before and during freezing on the functionality and fertilization ability of frozen-thawed spermatozoa. Design: Cryopreservation of raw semen samples with different known proportions of dead spermatozoa: native semen samples (<10%) and samples with 25%, 50%, and 75% dead spermatozoa. Setting: A university-based veterinary andrology laboratory. Animal(s): Five healthy and sexually mature boars. Intervention(s): Sperm killed by three fast-freezing cycles. Main Outcome Measure(s): Assessment of intracellular generation of reactive oxygen species (ROS), nuclear DNA fragmentation, in vitro fertilization (IVF), and embryo development. Result(s): High proportions of dead spermatozoa in raw semen samples before and during freezing induce statistically significantly increased ROS generation and nuclear DNA fragmentation in frozen-thawed spermatozoa. These dysfunctional changes resulted in low ratios of in vitro penetrated oocytes and healthy developing embryos. Conclusion(s): A high proportion of dead spermatozoa present in raw semen samples before and during freezing negatively influences the functionality and IVF outcomes of frozen-thawed spermatozoa.