Hypoosmotic swelling test with a medium of distilled water

Hypo-Osmotic Swelling Test (HOST) for Feline Spermatozoa: The Simplified Procedure and the Aspect of Sperm Morphology

Hypo-osmotic swelling test (HOST) is used to assess the functional integrity of sperm plasma membranes in many species. The primary aim of this study was to test a simplified HOST procedure for the evaluation of feline semen. The second objective was to check if sperm abnormalities can influence the results of this test. Urethral semen was collected from 19 male, domestic cats. In Exp. 1, HOST was performed in different media (50 mOsm/kg fructose or distilled water), temperature (37 °C or room temperature) and time (5 and 30 min). In Exp. 2, the potential effect of sperm abnormalities on HOST results was assessed by observing individual normal and abnormal spermatozoa microinjected into droplets of distilled water. The results showed no differences between the HOST results performed in different media, temperature and time. Viable abnormal spermatozoa were able to swell under hypo-osmotic conditions in the same manner as normal ones, except spermatozoa with distal droplets, which showed a higher frequency of ‘despiralization’. In conclusion, HOST can be reliably performed at 0 mOsm/kg for 5 min at room temperature, which may contribute to a wider use of this test under clinical environments. Viable abnormal spermatozoa are able to swell under hypo-osmotic conditions; therefore, their presence in the ejaculate would not bias the results of HOST when total coiling is calculated.

The effect of 20-week continuous 60 Hz magnetic field exposure on testicular function in sprague-dawley rats

Accumulating evidence does not yet confirm the effect of power line frequency magnetic field (MF) on human health and fertility. We recently reported that, at continuous 60 Hz MF exposure in mice, the dose given as magnetic flux density (tesla; T) and duration of exposure was related to induce testicular germ cell apoptosis. We aimed to characterize the effect of a 20-week continuous exposure to 60 Hz MF on the motility, morphology, and number of sperm as well as the apoptosis of testicular germ cell in rats. Sprague-Dawley rats were exposed for 20 weeks to 60 Hz MF of 2, 20, or 200 μT for 24 h/day with rats exposed to sham conditions, serving as the control. The exposure to 60 Hz MF of 2 and 20 μT had no effects on testicular in this study. The exposure to 60 Hz MF of 200 μT for 20 weeks induced increases of the apoptotic cells (P < 0.001) in germ cells and decreases of sperm numbers (P < 0.05). However, the MF did not significantly affect the body or testis mass, seminiferous tubule diameter, or the motility or morphology of sperm. This study concluded that exposure to 60 Hz MF of 200 μT can increase testicular germ cell apoptosis, especially spermatogonia, and reduce sperm count. Also compared to previous mice studies, rats are less sensitive than mice to exposure to 60 Hz MF. Bioelectromagnetics. 39:539-546, 2018. © 2018 Wiley Periodicals, Inc.

Semen quantity and quality correlate with bank vole males' social status

Laboratory studies reveal that in several rodent species the females prefer dominant males as mating partners. Here we investigate the correlation between bank vole males' social rank and their sperm quality and quantity. We used agonistic encounters to determine males' social status. Sperm quality was assessed by its motility, viability, maturity, morphology and sperm tail membrane integrity. Relatively more dominant males were heavier than males of lower social status. The males' social position affected the testes, seminal vesicles and coagulation gland development. The weights of these reproductive organs were significantly higher in more dominant males than in more subordinate males. Sperm counts and the values of the other parameters describing sperm quality were higher in high-ranking males than in subordinates. Our results suggest that bank vole females benefit from choosing and mating with high-ranking males by obtaining more and better-quality sperm.

Evaluation of human sperm membrane integrity using the water test and the hypoosmotic test

The objective of the study was to compare the water test and the hypoosmotic test (HOS) in the assessment of the human sperm membrane. A total of 686 semen samples from human male donors were subjected to water and HOS tests after routine semen evaluation. The mean percentage of swollen spermatozoa was 71.8 +/- 9.6% in the HOS test and 67.8 +/- 9.4% for the water test; these values were not statistically different. The correlation of coefficients between the water test and the HOS test was highly significant whether the values for the HOS test were higher or lower than 60% (P < 0.001). A poor correlation was obtained when the two tests were compared for sperm counts either higher or lower than 20 x 6 ml-1 and when the results for both tests were compared with the percentage of eosin-Y staining spermatozoa. A poor correlation was also obtained when the results of each test were compared with eosin-Y staining spermatozoa in normal and abnormal semen samples. The coefficient of regression between the two tests showed a high correlation (P < 0.001). In conclusion, even though a high correlation between the HOS test and water test was observed in this study, it is not possible to recommend assessment of sperm membrane integrity using the water test and the consequent replacement of the HOS test in routine practice. Further studies are necessary to establish the best test for sperm vitality.

Separation of canine epididymal spermatozoa by Percoll gradient centrifugation

The objective was to characterize the separation of canine epididymal spermatozoa on a Percoll gradient. Epididymal spermatozoa were overlaid on a 45 and 90% discontinuous Percoll gradient and centrifuged at 700 x g for 20 min. The Percoll column was separated into six fractions (top to bottom, A-F) after centrifugation. Fractions A-C contained few spermatozoa. Spermatozoa with bent or folded tails and a large amount of granular debris were observed in Fraction B. Fraction D contained many nonmotile spermatozoa, erythrocytes and round epithelial cells. Spermatozoa in Fraction E had significantly lower motility than those in the initial layer. Spermatozoa in Fraction F had motility similar to those before separation. Fraction F contained 40.6% of the motile spermatozoa layered and 67.5% of all motile spermatozoa recovered. There was no significant difference between Fraction F and the initial layer in sperm membrane integrity. In the sperm-oocyte penetration assay, spermatozoa from Fraction F had a significantly higher penetration rate into the immature homologous oocytes than those from Fraction E. Although the recovery rate of the motile spermatozoa was low, the canine epididymal spermatozoa with motility, membrane integrity and penetrating capability could be separated by two-layer discontinuous Percoll gradient centrifugation.

Evaluation of membrane integrity of canine epididymal spermatozoa by short hypoosmotic swelling test with ultrapure water

The effectiveness of the water test, short hypoosmotic swelling test with ultrapure water was examined in canine epididymal spermatozoa to evaluate tail membrane integrity. Spermatozoa during epididymal transit were also characterized. Sperm suspension obtained from cauda epididymis was diluted 1:4 with ultrapure water, and incubated for 5 min. The percentage of swollen spermatozoa in the water test was significantly correlated with both the sperm motility and the swelling value obtained by the conventional hypoosmotic swelling test. Canine spermatozoa collected from the caput epididymis were not motile, but revealed membrane integrity in a water test. The water test can be used as a simple and short hypoosmotic swelling test to evaluate the tail membrane integrity of canine epididymal spermatozoa.

Plasma membrane integrity of cryopreserved human sperm: an investigation of the results of the hypoosmotic swelling test, the water test, and eosin-Y staining

OBJECTIVE

[1] To examine the relationship between sperm membrane integrity and motion parameters before and after cryopreservation; [2] to determine the capacity of the membrane integrity tests to predict the outcome of cryopreservation in fertile and infertile men; and [3] to examine the degree of agreement between tail and head membrane integrity of testicular and ejaculated immotile sperm cryopreserved for intracytoplasmic sperm injection.

DESIGN

Prospective study.

SETTING

Academic tertiary care institution.

PATIENT(S)

Fertile donors and normozoospermic oligozoospermic, and asthenozoospermic subfertile men.

INTERVENTION(S)

Semen samples were cryopreserved and thawed for analysis.

MAIN OUTCOME MEASURE(S)

Sperm membrane integrity and computer-assisted motion parameters.

RESULT(S)

The hypoosmotic swelling test and water test had a significant and positive correlation in the fresh and cryopreserved ejaculates of all groups. The results of the hypoosmotic swelling test correlated positively with the percent motility in the fresh ejaculates of fertile and subfertile men. None of the membrane integrity tests correlated with the cryosurvival rate in any group. In the ejaculated and testicular samples with no postcryopreservation motility, the simultaneous assessment of hypoosmotic swelling test and eosin showed that of 33% sperm exhibiting coiling with the hypoosmotic swelling test, only 9% were eosin negative, whereas 24% were eosin positive.

CONCLUSION(S)

[1] The water test may be a simpler replacement for the hypoosmotic swelling test; [2] none of the membrane integrity tests predicted sperm motility after cryopreservation; and [3] there was a high degree of disagreement between the hypoosmotic swelling test and eosin in the samples with no postcryopreservation motility.

Sperm select penetration test reveals differences in sperm quality in strains with different Y chromosome genotype in mice

Mouse sperm penetration into a hyaluronic acid polymer (Sperm Select), hypoosmotic swelling in distilled water (water test), and eosin-Y staining were studied in sperm samples from males belonging to five inbred strains of mice (CBA, KE, KE-YCBA, B10.BR, and B10.BR-Ydel), which differ in the proportion of abnormal sperm heads and in efficiency of fertilization. Correlation coefficients, calculated from mean values for each strain, showed that Sperm Select penetration (to the depth of 1-2 cm) was significantly correlated with both sperm motility and fertilization efficiency, while correlation with the proportion of normal spermatozoa did not reach the level of significance. The indices of the water test and erosin Y staining were correlated with each other but not with Sperm Select penetration. In comparison with the B10.BR strain, its mutant strain B10.BR-Ydel, with a large deletion in the long arm of the Y chromosome and characterized by highly elevated proportion of abnormal sperm and low fertilization efficiency, showed lower values of the indices of all tests, suggesting that the partial deletion of the Y chromosome has affected various aspects of sperm morphology and function. On the other hand, for two consomic strains (KE and KE-YCBA with the Y chromosome introduced from the CBA strain), the difference in sperm morphology and fertilization rate was correlated with Sperm Select penetration but not with hypoosmotic swelling or eosin-Y staining; this suggests that only some aspects of sperm physiology are due to genetic differences between YKE and YCBA chromosomes.(ABSTRACT TRUNCATED AT 250 WORDS)