Recent developments and concepts in the cryopreservation of spermatozoa and the assessment of their post-thawing function

Abstract

New research on the cooling and cryopreservation of mammalian spermatozoa is reviewed in the context of the older literature. Cryoinjury to a variety of cell organelles is regarded as being due to the two major stresses of cryopreservation, i.e., the change in temperature, and the formation and dissolution of ice and its consequences. Since the cryopreservation process involves departure of the cells from and return to body temperature, both cold shock and warm shock are included as potential stresses to be considered, as well as the stages involving cooling below the freezing point of the medium. The causes of cryoinjury are reconsidered and new concepts concerning the influence of osmotic stress are presented. Heterogeneity of the sperm population is discussed in the context of the success with which spermatozoa can be cryopreserved between and within ejaculates and individuals. The functional state of frozen and thawed spermatozoa is examined on the basis of published results of structural and functional tests of sperm competence. The hypothesis is advanced that cryopreserved mammalian spermatozoa are in a state resembling capacitation, which accounts for their relatively reduced longevity and their readiness to undergo egg penetration without incubation. The importance of this to the utilization of cryopreserved spermatozoa is examined, and proposals are made for new avenues of research to overcome these problems.

Características do sêmen a fresco e descongelado de garanhões da raça Nordestina

“…Pugliesi et al (2012) não observaram diferenças (P>0,05) quanto à motilidade progressiva durante o TTR, nos tempos de 0, 20, 40, 60 e 90 minutos em Mangalarga Marchador, contudo observaram perda de 18,4% da motilidade progressiva do sêmen descongelado ao tempo 0 do TTR em comparação ao sêmen fresco (67,7% vs 49,3%), enquanto que Furst (2006) observou perdas de 28,6% no T0 e ao final do TTR (90 minutos) este valor não ultrapassou 50,0%. A diminuição na integridade funcional da membrana plasmá-tica do espermatozoide após o TTR parece ocorrer devido aos danos causados pelo processo de criopreservação nas estruturas e organelas envolvidas na movimentação espermática (Watson 1995).…”

Toxicity of glycerol for the stallion spermatozoa: Effects on membrane integrity and cytoskeleton, lipid peroxidation and mitochondrial membrane potential

“…One possible explanation for our findings is that human spermatozoa is very permeable to glycerol [16], so this changes in cellular volume occurs in a short period, while the more impermeable membrane of the stallion spermatozoa makes this process to occur much more slowly and thus causing more damage. It has been hypothesized that the actin cytoskeleton is damaged during cryopreservation [35,36] and indirect evidence have been described in ram spermatozoa [37]. In order to further determine if glycerol may damage the sperm cytoskeleton the percentage of F actin was evaluated.…”

Development of a simplified and standardized protocol with potential for high-throughput for sperm cryopreservation in zebrafish Danio rerio

“…The reasons for the variation in the susceptibility of spermatozoa to injury could lie in differences that have been identified in sperm quality such as membrane integrity and functionality, adenosine triphosphate (ATP) content, and mitochondrial functionality [21]. Recent studies suggest that there is a genetic basis for variation in thawed sperm quality, and also suggest that molecular technologies could identify markers linked to genes influencing this variation [24,25]. In the present study, gonadosomatic index and body condition factor were recorded and are suggested as indicators for evaluating zebrafish sperm quality for cryopreservation.…”