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

Capsule:
A high proportion of dead spermatozoa in raw semen samples increases the generation of endogenous reactive oxygen species and nuclear DNA fragmentation when frozen-thawed, impairing IVF ability and embryo development.

Authors:
Jordi Roca, Ph.D., Maria J. Martinez-Alborcia, D.V.M., Maria A. Gil, Ph.D., Inmaculada Parrilla, Ph.D., Emilio A. Martinez, Ph.D.

Volume 100, Issue 3, Pages 875-881, September 2013

Abstract:

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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