The variability of measuring sperm concentration and motility as determined by computer assisted image analysis and visual estimation

Effects of sub-chronic oral exposure to pyrogenic synthetic amorphous silica (NM-203) in male and female Sprague-Dawley rats: focus on reproductive systems

Synthetic amorphous silica (SAS) consists of agglomerates and aggregates of primary particles in the nanorange (<100 nm) and it is the E551 authorized food additive. The potential risks for human health associated to dietary exposure to SAS are not completely assessed; in particular, data on male and female reproductive systems are lacking. A 90-day oral toxicity study with pyrogenic SAS nanomaterial NM-203 was carried out on the basis of the OECD test guideline 408 in the frame of the NANoREG project. Adult Sprague-Dawley rats of both sexes were orally treated for 90 days with 0, 2, 5, 10, 20 and 50 mg SAS/kg bw per day. Dose levels were selected to be as close as possible to the expected human exposure to food additive E551. The present paper provides specific information on potential effects on male and female reproductive systems, through the evaluation of serum biomarkers, sperm count, histopathological analysis of testis, epididymis, ovary and uterus and real-time PCR on uterus; potential genotoxic alterations were evaluated by comet assay on testis, sperm and ovary. NM-203 did not induce histophatological and genotoxic effects in male reproductive system. In female rats, ovary is not target of NM-203 and only tissue-specific effects on uterus were recorded up to 10 mg/kg bw per day. To our best knowledge, this is the first study providing data on male and female reproductive systems after long-term, repeated oral exposure at dose levels close to dietary human exposure, which identifies a limited concern only for female reproductive health.

A Flow Cytometric Method for Rapid Determination of Sperm Concentration and Viability in Mammalian and Avian Semen

A new flow cytometric method has been developed to rapidly determine sperm concentration and viability in semen from bulls and boars. Sperm viability was determined on the basis of staining with SYBR-14 and propidium iodide (PI), and this allowed detection of live (membrane-intact) sperm, dying (moribund) sperm, as well as dead cells. Fluorescent microspheres (beads) were used to determine sperm concentration. The use of SYBR-14 at 50 nM and PI at 12 micro M in combination with the FACSCount diluent in the counting tubes resulted in a uniform staining after 2.5-5 minutes at room temperature. Reagent staining was reproducible enough to allow subsequent semiautomated analysis of data using Attractors software. In experiment 1, this method was used to analyze semen from boars, rams, rats, rabbits, humans, and turkeys. In experiment 2, Attractors analysis was performed by the FACSCount AF flow cytometer, and sperm concentration determination with this system was compared with results obtained by a spectrophotometer and an electronic cell counter, which is routinely used by bull artificial insemination centers. When compared to microscopic counting in a hemocytometer, the FACSCount AF flow cytometer was two and four times more accurate than the spectrophotometer and the electronic cell counter, respectively. In addition, the FACSCount AF flow cytometer determined both sperm concentration (coefficient of variation 3.3%) and sperm viability (coefficient of variation 0.7%) with high precision.

Comparison of motility and membrane integrity to assess rat sperm viability

Rat sperm motility and membrane integrity were compared as endpoints for viability. Sperm motility was measured by computer-assisted semen analysis (CASA), whereas membrane integrity was assessed by flow cytometric analysis of sperm stained with two nucleic acid stains, SYBR-14 and propidium iodide. The two techniques were compared in experiments that examined sperm viability over time and by analysis of known mixtures of control and freeze/thaw-killed sperm. Results from the two approaches were quantitatively very similar. Sperm from rats treated with dibromoacetic acid (600 or 1200 mg/kg) or alpha-chlorhyrin (100 mg/kg) were also analyzed. Neither technique detected a treatment-related effect with dibromoacetic acid. CASA identified a significant decrease in sperm motility in alpha-chlorhyrin-treated rats, whereas flow cytometric analysis did not find a measureable change in sperm membrane integrity. Because decreases in sperm motility would be expected to directly affect fertility, CASA may be a more robust endpoint for risk assessment in reproductive toxicology studies than flow cytometric analysis of membrane integrity.

Computer-aided semen analysis: sperm concentration assessment by the Strömberg-Mika system

The scope of this study was to evaluate the accuracy, precision and specificity of the sperm concentration measurements by the Strömberg-Mika Cell Motion Analyser (SM-CMA). Our data show that the instrument generally underscores the sperm concentration and therefore the uncorrected measurements must be corrected by the operator using the 'mouse'-driven option. In terms of precision, the system appears to have an excellent internal precision whereas its repeatability is influenced by the sperm concentration, the sample's homogeneity and the correction of the raw data. In order to increase the system's repeatability, we suggest that sperm counts should be carried out in various fields of the counting chamber, and the mean of the corrected values be taken as representative of the sperm concentration in the ejaculate if the various measurements show a homogeneous (poissonian) distribution. The correction of the raw data with the 'mouse'-driven correction option was also shown to improve the system's reproducibility. Concerning specificity, our data evidenced that, without technical correction, the instrument failed to correctly classify certain spermatozoa as such, thereby grossly underscoring sperm counts. This finding was more evident at low sperm counts. Overall, the SM-CMA requires additional laboratory time but the corrected sperm counts are comparable to manual counts and semi-automated counts with the added option that it provides the andrologists with various motility characteristics not possible with the latter methodologies.