Dead spermatozoa in raw semen samples impair in vitro fertilization outcomes of frozen-thawed spermatozoa
2013
Roca, Jordi | Martinez-Alborcia, Maria J. | Gil, Maria A. | Parrilla, Inmaculada | Martinez, Emilio A.
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.
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