The routine assessment of sperm motility at room temperature and 37 degrees C

Analytical variability and interpretation of results of a 3-category sperm motility assessment: 5 years' of an Australian external quality assurance programme

RESEARCH QUESTION

How do laboratories perform when assessing sperm motility with a 3-category system and interpreting results as per the fifth edition of the World Health Organization manual (WHO5), and will the use of a 4-category system as per the sixth edition of the WHO manual improve their performance?

DESIGN

Eighty video recordings of sperm samples were sent to over 200 laboratories spanning a 5-year period for the assessment of progressive motility. The results were reviewed relative to the all-laboratory trimmed mean (ALTM) in terms of the minimum and maximum values reported, the coefficient of variation and the proportion of laboratories indicating an abnormal result. A further 20 video recordings were sent over 1 year, with 6-11 laboratories per distribution adjusting to reporting rapid progressive motility using the 4-category system.

RESULTS

For the 3-category system, the videos covered a mean assessed progressive motility range of 12.0-81.1%. The mean difference between the minimum and maximum values per sample was 50.3% and the coefficients of variation were negatively correlated with the ALTM (r = -0.87, P < 0.00001). Progressive motility abnormality reporting formed a sigmoid curve, and the inflection point (50% of laboratories identifying an abnormality) gave an ALTM value of 32.01%. Preliminary results for laboratories using the 4-category system showed no performance improvement but the number of laboratories was small.

CONCLUSIONS

Analytical variation can result in laboratories crossing the clinical cut-off of the lower reference limit for samples whose motility is close to the WHO5 lower reference limit, but is less important for samples with extreme values. The benefits of a 4-category motility system are yet to be shown.

The effect of adjusting settings within a Computer-Assisted Sperm Analysis (CASA) system on bovine sperm motility and morphology results

Semen motility is the most widely recognized semen quality parameter used by Artificial Insemination (AI) centers. With the increasing worldwide export of semen between AI centers there is an increasing need for standardized motility assessment methods. Computer-Assisted Sperm Analysis (CASA) technology is thought to provide an objective motility evaluation; however, results can still vary between laboratories. The aim of present study was to verify the impact of different setting values of the CASA IVOS II on motility, concentration, and morphology of bovine semen samples frozen in an extender with or without egg yolk and then decide on optimal settings for a further validation step across AI centers. Semen straws from 30 different bulls were analyzed using IVOS II with twelve modified settings. No significant changes were observed in semen concentration, percentage of motile sperm or kinetic results for either extender type. However, increasing settings for both STR and VAP progressive (%) from Low, Medium, and High cut-off values significantly (p<0.05) reduced the percentage of detected progressive spermatozoa, in egg yolk extender from 49.5±15.2, 37.2±11.9 to 11.9±5.3%, and in clear extender from 51.9±9.1, 35.8±7.3 to 10.0±2.4%, respectively. In clear extender only, the modification of droplet proximal head length significantly affected the detection of normal sperm percentages (88.0± 4.7 to 95.0±0.6 and 96.0±0.6%) and of the percentage of detected proximal droplets (12.2±4.7, 2.5±2.7 to 0.6±0.2%) for Low, Medium and High values respectively (p<0.05). The identification of sensitivity within the CASA system to changes in set parameters then led to the determination of an optimal IVOS II setting. The existing variability among centers for these phenotypes was reduced when the standardized settings were applied across different CASA units. The results clearly show the importance of applied settings for the final CASA results and emphasize the need for standardized settings to obtain comparable data.

Influence of temperature and sperm preparation on the quality of spermatozoa

This study investigated the effects of long-term (24h) in-vitro sperm incubation at room temperature (RT; 23°C) versus testis temperature (35°C) on various sperm-quality parameters. Semen samples (n=41) were prepared both by density-gradient centrifugation (DGC) and the swim-up technique in order to compare the influence of sperm preparation on sperm quality after incubation. Progressive motility and morphology were significantly higher after incubation at RT compared with 35°C (P<0.001 and P<0.01, respectively). The proportions of acrosome-reacted, apoptotic and dead spermatozoa were significantly lower in samples incubated for 24h at RT compared with 35°C (P<0.001, P=0.01 and P<0.001, respectively). The number of motile, morphologically normal, non-acrosome-reacted and nonapoptotic spermatozoa recovered after sperm preparation was significantly higher in DGC compared with swim-up samples (P<0.001). However, spermatozoa prepared by swim-up showed better survival after incubation compared with DGC-prepared spermatozoa, especially when incubated at 35°C. In conclusion, this study indicates a significantly better and longer preservation of sperm quality when incubation is performed at RT. These findings may convince laboratories to change the routinely used sperm storage conditions in order to maximize the quality of the prepared sperm sample.

The effect of temperature on sperm motility and enzymatic activity in brown trout Salmo trutta, burbot Lota lota and grayling Thymallus thymallus

The effect of temperature on sperm motility was investigated in brown trout Salmo trutta, burbot Lota lota and grayling Thymallus thymallus using water and sperm motility prolonging saline solution (SMPS) for motility activation. The effect of temperature (4-20° C) on spermatozoal enzymes for energy supply [malate dehydrogenase (MDH), pyruvate kinase (PK), adenylate kinase (AK)], flagellar movement [Mg(2+) adenosine triposphatase (ATPase)] and oxidative defence [peroxidase (POX)] were measured in S. trutta and L. lota. Temperatures yielding the highest initial sperm motility rates and swimming velocities were 4-6° C for S. trutta [investigated range (IR) = 4-12° C] and L. lota (IR = 2-8° C) and 8-16° C (IR = 4-16° C) for T. thymallus. Motility variables were re-measured after 30 s in S. trutta, after 45 s in T. thymallus and after 60 s in L. lota in water and after 2 min in all investigated species in SMPS. Motility variables were increased by low temperatures and the results differed between water and SMPS. In S. trutta and L. lota, the temperature resulting in highest activities of MDH, PK, AK and ATPase was 4° C. POX had a very narrow temperature optimum at 20° C in both species. This may indicate that the temperature optimum of enzymes of energy supply and flagellar movement are closely related to motility. The present data show that the variables are affected by temperatures in an ecologically relevant range. Too low, as well as too high temperatures affected sperm motility, and the winter spawners (S. trutta and L. lota) have a narrower temperature optimum than the spring spawner T. thymallus.

On the Origin of Descended Scrotal Testicles: The Activation Hypothesis

Male gonads contained in an unprotected skin sack located outside the body cavity are a peculiar mammalian anomaly. We advance the hypothesis that descended scrotal testicles in humans and many other mammals evolved to provide a situation specific means of activating sperm. As a result of consistent temperature differences between the male and female reproductive tracts (i.e., scrotal temperatures are typically maintained at 2-3°C below body temperature), we propose that the rise to body temperature that accompanies insemination into the vagina serves as one of several triggers for the activation of sperm. We explore some of the features of mammalian reproduction and behavior that are consistent with this hypothesis, make some testable predictions, and examine the psychological and behavioral adaptations that have evolved to protect otherwise vulnerable scrotal testicles from damage.

Evaluation of the "Hamilton Thorn computer-based automated system" for dog semen analysis

An objective evaluation of semen is warranted to assess the canine male fertility and to select appropriate techniques and extenders for semen preservation. With conventional microscopic evaluation, the subjectivity of the analysis makes any comparison of results difficult. In the present study, we validated the Hamilton Thorn computer-aided semen analyzer (HTR-IVOS10 analyzer) for objective assessment of canine semen. A description of fertile canine motility parameters using this analyzer is reported. Semen analysis at 38 degreesC is found to be more optimal and accurate than 30 degreesC. The Makler chamber was preferred to the Cell-vu, which induced a decrease of all semen motility parameters. The repeatability of the measures was good with intra-and inter-assay coefficients of variation below 10% and 20%, respectively, for most of measured parameters. An overestimation of semen concentration, increasing with dilution of semen, was observed when HTR-IVOS10 results were compared with the classical manual Makler cell evaluation. A significant decrease in semen motility parameters was recorded when high semen dilutions were used. Generated from the analysis of 42 mature fertile male beagle dogs, a description of semen motility parameters using the CASA system is presented to serve as reference when comparing Beagle ejaculates both in clinical and experimental studies.