Correlation between human sperm swelling in hypoosmotic medium (hypoosmotic swelling test) and in vitro fertilization

Establishment of methods to analyze the structural and functional integrity of the quail (Coturnix coturnix japonica) sperm plasma membrane

1. The objectives of this study were to establish the use of the fluorophores Hoechst 33342 and propidium iodide for the evaluation of sperm plasma membrane integrity and to identify an adequate hypoosmotic solution for the evaluation of sperm membrane functionality in quails.2. Sperm samples were collected from the vas deferens of nine quails. After initial evaluation, the samples were subjected to a flash-frozen assay. Three treatments with the following proportions of fresh sperm and sperm subjected to flash freezing were prepared as follows: 100:0 (T100), 50:50 (T50), and 0:100 (T0). The hypoosmotic swelling test used distilled water (0 mOsm/l) and fructose solutions (50, 100, and 200 mOsm/l).3. Immediately after recovery, the samples showed 75.6 ± 5.0% motility with vigour of 3.7 ± 0.3 and 96.1 ± 0.5% of the sperm appeared normal. The membrane integrity test showed 62.2 ± 5.2% intact sperm at T100, 29.0 ± 4.1% at T50 and 0.1 ± 0.1% at T0. Moreover, a greater number of reactive sperm (74.7 ± 6.7%) were observed when incubated in distilled water (0 mOsm/l) in comparison to other solutions (P < 0.05).4. The association of fluorescent probes composed of Hoechst 33342 and propidium iodide provided an efficient assessment of the integrity of the plasmatic membrane of quail spermatozoa. However, the study identified that the hypoosmotic swelling test has little predictive value regarding sperm membrane functionality in this species.

The hypo-osmotic swelling test: Is it a sperm vitality or a viability assay?

The first two editions of the World Health Organization laboratory manual described the determination of live spermatozoa by a dye exclusion method as a sperm "viability" test, whereas subsequent editions classified it as a "vitality" test, without providing an explanation for the reclassification. Additionally, the hypo-osmotic swelling (HOS) test, which assesses the functional integrity of the human sperm membrane, was placed in the same category as the dye exclusion test. Although the two terms might seem synonymous, the term "vitality" merely means "alive," whereas "viability" assesses qualities or physiological functions of a living entity. After comparing the morphological, physiological, and clinical findings obtained from dye exclusion testing vs. the HOS test, we conclude that the HOS test should be classified as a viability test, not merely as a vitality test.

Detailed cell-level analysis of sperm nuclear quality among the different hypo-osmotic swelling test (HOST) classes

PURPOSE

We studied the quality differences between the different hypo-osmotic swelling test (HOST) classes, as measured by criteria of DNA fragmentation, DNA decondensation, and nuclear architecture. The aim was to find particular HOST classes associated with good-quality metrics, which may be potentially used in ICSI (intra-cytoplasmic sperm injection).

METHODS

Ten patients from the Department of Reproductive Medicine at Tenon Hospital (Paris, France) were included. Their semen samples were collected and divided into two fractions: one was incubated in a hypo-osmotic solution as per HOST protocol and sorted by sperm morphology, and a second was incubated without undergoing the HOST protocol to serve as an unsorted baseline. Three parameters were assessed: DNA fragmentation (TUNEL assay), DNA decondensation (chromomycin A3 assay), and nuclear architecture (FISH, with telomeric and whole chromosome painting probes). The different HOST classes were evaluated for these three parameters, and statistical analysis was performed for each class versus the unsorted non-HOST-treated sperm. Results with p<0.05 were considered statistically significant.

RESULTS

For each of the parameters evaluated, we found significant differences between HOST-selected spermatozoa and non-selected spermatozoa. Overall, spermatozoa of HOST classes B and B+ exhibited the highest quality based on four metrics (low DNA fragmentation, low DNA decondensation, short inter-telomeric distance, and small chromosome 1 territory area), while spermatozoa of HOST classes A and G exhibited the poorest quality by these metrics.

CONCLUSION

In addition to their pathophysiological interest, our results open possibilities of sperm selection prior to ICSI, which may allow for optimization of reproductive outcomes in heretofore unstudied patient populations.

Conventional semen analysis and advanced sperm function tests in diagnosis and management of varicocele

Clinical varicoceles are a common cause of male infertility and affect sperm parameters as measured in a conventional semen analysis. Varicocelectomy has been shown in prospective studies to improve semen parameters in men with a clinical varicocele. Clinical varicoceles are also a well-known source of oxidative stress which may affect the quality of spermatozoa. Spermatozoa are particularly susceptible to oxidative stress due to a limited capacity for DNA repair. The susceptibility of spermatozoa to oxidative stress is modulated by a balance between ROS and antioxidants, which can be quantified by various laboratory assays. Varicocelectomy has been consistently shown to reduce both ROS and sperm DNA fragmentation, and various assays should be utilised in the diagnosis and treatment of infertile men with a clinical varicocele.

The use of aniline blue chromatin condensation test on prediction of pregnancy in mild male factor and unexplained male infertility

The aim of this study was to investigate the possibility of using sperm function tests (hypoosmotic swelling test [HOS], aniline blue [AB] staining test, and sperm chromatin dispersion [SCD]) to predict intrauterine insemination [IUI] success rate. A total of 243 couples with mild male factor or unexplained male infertility who underwent IUI were evaluated prospectively. The results of basic sperm analysis and sperm function tests were compared between pregnant or nonpregnant groups. The HOS (11.9 ± 9.6% vs. 10.1 ± 8.5%, p = 0.35) and SCD tests (32.9 ± 21.0% vs. 29.9 ± 19.0%, p = 0.48) were not significantly different between pregnant (n = 22) and nonpregnant (n = 221) groups. However, the AB staining negativity rate was significantly higher in the pregnant group compared to the nonpregnant group (35.2 ± 20.8% and 24.4 ± 18.0%, p = 0.008). On ROC analysis, a cut-off value of 24% for AB negativity showed a sensitivity and a specificity value of 82.35% and 51.38% (AUC) = 0.653; 95% confidence interval: 0.571-0.72 P (Area = 0.5) = 0.0267, respectively, for prediction of pregnancy. Our study showed that the sperm chromatin maturity, assessed by AB stain, may predict the pregnancy in couples with unexplained female infertility plus mild male factor or unexplained male infertility. The HOS and SCD failed to predict the pregnancy in this group of couples.

Mitigation of sperm tail abnormalities using demembranation approach in the clouded leopard (Neofelis nebulosa)

Clouded leopards (Neofelis nebulosa) produced high proportion of abnormal spermatozoa (mainly tail defects) that can limit sperm movement and conception. The study aimed to better identify the origin of those defects using a demembranation approach. Ejaculates (1-2 ejaculations/male; n = 9) were allocated to simple washing (control; resulting in 11.7% ± 1.9% coiled tails) and processed through colloid centrifugation to reduce the number of sperm with tail defects (treatment, resulting in 5.9% ± 0.9% coiled tails). Aliquots of semen were incubated in hypo-osmotic solution (HOS, 60 mOsm fructose solution) containing 5 mM dithiothreitol (DTT) (a reducing agent) to prevent oxidation of sperm membrane. Thereafter, 20% Triton X-100 (TX) (a detergent) was added to the HOS/DTT-treated samples. After HOS/DTT incubation, the control samples and sperm-selected samples presented 73.4% ± 3.1% and 73.9% ± 2.5% swollen sperm (bent and coiled) indicating membrane intact, respectively. Most of the coiled tail in the raw ejaculates could not be opened by TX indicating that the cause of coiled sperm tails may be from testicular origin. The proportion of sperm with tightly coiled tail tended to be lower in the sperm-selected group than control group (18.8% ± 3.8% and 26.5% ± 3.4%; p = .1), whereas the sperm opened up by TX tended to be higher in the sperm-selected group (53.6% ± 10.4% and 21.1% ± 7.9%; p = .06). The results indicated TX was able to uncoil half of the tightly coiled sperm in the semen undergone preparation. In conclusion, the coiled sperm in the clouded leopard semen were likely not a defect of sperm volume regulation during post-ejaculate (osmotic swelling) but pre-ejaculate origin. Semen preparation demonstrated its ability to lessen the primary sperm defects and selected spermatozoa that were prone to be mitigated after demembranation.

Tolerance of spermatozoa to hypotonic stress: role of membrane fluidity and correlation with cryosurvival

The aim of this study was to evaluate inter-individual variability in osmotic properties of stallion spermatozoa and its correlation with cryosurvival. In addition, temperature dependency of hypo-osmotic tolerance and membrane fluidity were studied. Stallion sperm membranes exhibited good resistance towards hypotonic stress in the 15–30°C temperature range, whereas membrane stability was found to be decreased at 4 and 37°C. Bull spermatozoa showed greater hypo-osmotic tolerance compared with stallion spermatozoa, especially at temperatures above 30°C, which coincided with decreased membrane fluidity of bovine spermatozoa in this temperature range. The critical osmolality at 22°C, at which half of the sperm population survived exposure to hypotonic saline solution, was found to vary between 55 and 170 mOsm kg–1 among different stallions. Clear correlations were found for pre- versus post-freeze sperm motility and membrane integrity. Pre-freeze percentages of membrane-intact spermatozoa after exposure to hypotonic stress showed a weak correlation with sperm motility after cryopreservation. This correlation, however, was not found when data were corrected for initial numbers of membrane-intact spermatozoa in the sample. We thus conclude that studies on pre-freeze tolerance towards hypotonic stress cannot be used to predict sperm cryosurvival rates for individual stallions.

Review on the screening of semen by hypo-osmotic swelling test

The hypo-osmotic swelling test (HOST) is widely used as a valuable test for determining sperm quality by evaluating the membrane integrity of spermatozoa of various domestic animals including cattle, horses and swine. The HOST has also been used as an indicator of the fertilising capacity of spermatozoa. This test is based on the swelling ability when functional spermatozoa submitted to hypo-osmotic solutions. This test is commonly used as an important parameter for the evaluation of semen due to its strong correlation with semen evaluation parameters. The objective of this review was to analyse its significance in semen evaluation, swelling of spermatozoa under various osmolarities and variations in swelling percentage under different seasons.

The hypo-osmotic swelling test for evaluation of sperm membrane integrity

A functional membrane is requisite for the fertilizing ability of spermatozoa, as it plays an integral role in sperm capacitation, acrosome reaction, and binding of the spermatozoon to the egg surface. The hypo-osmotic swelling (HOS) test evaluates the functional integrity of the sperm's plasma membrane and also serves as a useful indicator of fertility potential of sperm. The HOS test predicts membrane integrity by determining the ability of the sperm membrane to maintain equilibrium between the sperm cell and its environment. Influx of the fluid due to hypo-osmotic stress causes the sperm tail to coil and balloon or "swell." A higher percentage of swollen sperm indicates the presence of sperm having a functional and intact plasma membrane. Here, we present the detailed protocol for performing the HOS test and explain the results for interpretation.

Retrospective analysis of canine semen evaluations with special emphasis on the use of the hypoosmotic swelling (HOS) test and acrosomal evaluation using Spermac(®)

Routine semen evaluation includes volume, motility, vital staining for live-dead ratio and pathomorphology including Spermac(®) staining for evaluation of the acrosome. In recent years, depending on the species, also the hypoosmotic swelling (HOS) test has been applied routinely for evaluation of semen quality. In this respect, a significant correlation between the ability of spermatozoa to swell in HOS test and the fertilizing ability has been reported. Also for evaluation of dog semen, reference has been made to the HOS test; however, its correlation to conventional semen parameters so far is discussed controversially. In the present study, the results of 400 semen examinations from stud dogs presented at our clinic were evaluated for their correlations between conventional semen parameters (motility, live/dead ratio, pathomorphology), conventional semen parameters and age, Spermac(®) staining and HOS test, respectively. We found a significant correlation of age and sperm concentration (p < 0.01), total sperm count (p < 0.0001), percentage of progressively motile sperm (p < 0.01) and live spermatozoa (p = 0.012). Furthermore, several correlations between conventional semen parameters were identified. Percentage of sperm with normal acrosome identified by Spermac (®) staining correlated significantly with live spermatozoa (p < 0.0001) and percentage of progressively motile sperm (p < 0.01). A significant correlation was proven between curled tails in HOS test and age (p < 0.001), motility (p < 0.0001), live sperm (p < 0.0001), acrosomal status (p < 0.05), pathomorphology (p < 0.0001) and sperm concentration (p = 0.011). These results indicate that Spermac(®) staining and the HOS test are useful in improving canine semen analysis.

An assessment of new sperm tests for male infertility

The routine semen analysis, although used for more than 50 years, fails to accurately distinguish between fertile and infertile men. As a consequence, many tests of sperm function (TSF) have been developed. This review discusses both older and newer diagnostic TSF. It outlines the principles underlying each assay and reviews aggregate clinical data to determine its current relevance and utility. It concludes that the relevance of many older TSF is questionable, with the wide acceptance of intracytoplasmic sperm injection (ICSI). Newer TSF have the potential to deliver more clinically relevant information but require more extensive study to better understand their predictive role in the ICSI era.

EVALUATION OF CELL MEMBRANE INTEGRITY OF SPERMATOZOA BY HYPOOSMOTIC SWELLING TEST – “WATER TEST” IN MICE AFTER INTRAPERITONEAL DAIDZEIN ADMINISTRATION

The functional integrity of the cell membrane of the mice sperm after daidzein administration intraperitoneal was assessed by studying the swelling reaction of the sperm when suspended in distilled water. The results obtained in water test indicate that daidzein, one of the phytoestrogens, decreases the number of normal and live sperm (swollen) in the samples obtaining from vas deferens. This effect was statistically significant in the mice after 7 and 14 days of daidzein administration. In mice treated with daidzein the number of dead (unswollen) sperm was increased, especially in animals after 14 days of experiment.

Sperm Dna Integrity: Correlation With Sperm Plasma Membrane Integrity In Semen Evaluated For Male Infertility

Previous independent studies have indicated that abnormally low parameters of sperm DNA integrity and sperm membrane integrity correlate to reduced fertility due in part to implantation disorders. The purpose of our study was to evaluate the relationship between sperm plasma membrane functional integrity assessed by the hypo-osmotic swelling test (HOST) and sperm DNA integriy test assesed by DNA fragmentation index (DFI). Semen samples from 102 random patients were evaluated in terms of standard semen parameters and assessed by DFI and HOST. Both tests showed a significant correlation to standard semen parameters (p < .05). In addition, patients with abnormal HOST results had a higher likehood of a subnormal or abnormal DFI result (p < .001). Our results suggest that a common sublethal insult may manifest as abnormalities in both the nucleus and the plasma membrane that act at the implantation and/or subsequent levels of development rather than at the fertilization stage.

Split-sample comparison of directional and liquid nitrogen vapour freezing method on post-thaw semen quality in white rhinoceroses (Ceratotherium simum simum and Ceratotherium simum cottoni)

To increase the quality of cryopreserved sperm in white rhinoceros, the liquid nitrogen vapour (LN vapour) freezing and the multi-thermal gradient directional freezing methods were compared. Sixteen white rhinoceros (Ceratotherium simum sp.) were electro-ejaculated. Semen samples were diluted with cryoextender (Tris, lactose, egg-yolk, DMSO) and aliquoted into straws for LN vapour freezing, and glass hollow tubes for directional freezing. The sperm quality was evaluated before and after freezing by assessing the following parameters: motility, morphologic state, acrosomal integrity and plasma membrane function and integrity (i.e. sperm viability) as defined by the hypo-osmotic swelling. Directional freezing improved the sperm viability by 5.6% (p<0.005), progressive motility score by 34.7% and sperm motility index (SMI) by 8.1% (p<0.005) versus LN vapour freezing. When data was categorized into groups of low (<19%), moderate (20-39%) and high (>40%) percentages of morphologically normal, directional freezing (DF) resulted in 31.4% less abnormal acrosomes for the low quality group as well as 18.7% increase in intact acrosomes and 10.9% increase in motility for the high quality group compared to LN vapour freezing (LN) (p<0.01, p<0.03, p<0.01, respectively). LN showed a significant reduction in sperm head volume (5.7%, p<0.05) compared to the prefreeze; whereas, no significant reduction in head volume was demonstrated after DF. Several additives (xanthenuric acid, cytochalasin D, potassium, EDTA) to the basic cryoextender provided no significant improvement in spermatozoal survival after directional freezing. In conclusion, directional freezing proved to facilitate higher gamete survival compared to LN vapour freezing. This is especially effective in ejaculates of low sperm quality and is important in endangered species where high quality semen donors are often not accessible. These results suggest that directional freezing could be valuable particularly for species with limited freezability of spermatozoa.

Evaluation of sperm functional attributes in relation to in vitro sperm-zona pellucida binding ability and cleavage rate in assessing frozen thawed buffalo (Bubalus bubalis) semen quality

The objective of this study was to evaluate sperm functional attributes in relation to in vitro sperm-zona binding ability and cleavage rate in assessing frozen thawed buffalo (Bubalus bubalis) semen quality. Frozen-thawed forty-eight ejaculates from eight Surti buffalo bulls (six ejaculates/bull) obtained by artificial vagina were used. Frozen semen from each bull was thawed, pooled, and subjected for sperm functional (six replicates) and in vitro fertilization (four replicates) tests. The progressive forward motility, plasmalemma functional integrity assessed by fluorogenic [6-carboxyfluorescein diacetate (CFDA), and propidium iodide (PI)], hypoosmotic swelling (HOS), and hypoosmotic swelling-Giemsa (HOS-G) test, mitochondrial membrane potential, sperm nuclear morphology, the number of sperm bound to zona and cleavage rate differed significantly (P<0.05) between bulls. When the animals were grouped based on cleavage rate (group I, >40% cleavage rate, n=5, and group II, <40% cleavage rate, n=3), in vitro fertility parameters and all the sperm functional attributes except sperm nuclear morphology differed significantly (P<0.05). The proportions of sperm with functional plasmalemma in the tail and intact acrosome assessed by HOS-G test (25.33, range: 17.48-40.27) were significantly (P<0.001) lower than the functional plasmalemma in the tail assessed by HOS test (39.80, range: 27.85-54.67). The number of sperm bound to zona had significant correlations with the mitochondrial membrane potential (r=0.90, P<0.01) and plasmalemma integrity (fluorogenic, r=0.74 and HOS, r=0.79, P<0.05) and HOS-G, r=0.87, P<0.01). The cleavage rate had significant (P<0.05) correlations with the mitochondrial membrane potential (r=0.70) and plasmalemma integrity measured by HOS-G test (r=0.68). The present study indicates that these attributes could represent important determinants of buffalo sperm quality influencing cleavage rate.

Adaptation to long sperm in Drosophila: correlated development of the sperm roller and sperm packaging

Sperm are generally small and produced in huge numbers, but some species combine exaggerated sperm length with extremely limited numbers of sperm, an evolutionary trend that deviates from the theory of anisogamy. Sperm gigantism has arisen recurrently in various species, but insects exhibit the longest sperm, with some species of the Drosophilidae family producing sperm up to 6 cm in length. The anatomical, cytological, and physiological requirements for males to cope with these giant sperm were hitherto poorly understood. In this paper, we investigate the internal morphology of the male reproductive tract, and highlight specific features that may be linked to this increase in sperm size. We focus on species in the repleta group, within which sperm length varies by a factor of 35. An associated development of the sperm roller, a special twisting device inserted between the testis and the seminal vesicle, is demonstrated. Its length and the number of coils involved increase with sperm size, and it allows individual sperm to swell and roll into a spermatic pellet before reaching the seminal vesicle. This process occurs independently of and in addition to the sperm bundle coiling that takes place at the base of the testis. It is suggested that the emergence and development of the sperm roller may be a male adaptation to sperm gigantism.

Simplified hypoosmotic swelling testing (HOST) of fresh and frozen-thawed canine spermatozoa

The clinical use of the hypoosmotic swelling test (HOST) to identify spermatozoa with a functional intact membrane has been reported for humans and domestic species, including the dog. Currently, it is recommended that canine spermatozoa be incubated with the hypoosmotic solution for periods that range from 30 to 60 min. In an attempt to simplify the test, it was hypothesized that the degree of the hypoosmotic response at 1 min of incubation would not be different from the response documented at 60 min after incubation in the hypoosmotic solution at 37 degrees C. The hypoosmotic response of spermatozoa from 50 fresh and 16 frozen-thawed semen samples obtained from 22 adult dogs was recorded at 1 and 60 min of incubation. There were no significant differences between the hypoosmotic response recorded at 1 and 60 min for all evaluated semen samples (P>0.10). The hypoosmotic response recorded for canine spermatozoa from fresh semen samples were greater than that recorded for spermatozoa from frozen-thawed semen, both at 1 min (86.2% compared with 65.2%; P<0.001) and 60 min (85.6% compared with 61.8%; P<0.001). Based on the results of this study, it is recommended to decrease the incubation time of the HOST for canine spermatozoa to as short a period as 1 min. This incubation time should encourage the application of this relatively simple and inexpensive test of canine sperm membrane function in a clinical setting.

The potential fertility estimation capacity of the hypoosmotic swelling test, the thermal stress test and a modified cervical mucus penetration test in the bovine

In this study, hypoosmotic swelling (HOS), thermal stress (TS) and modified cervical mucus penetration (mCMP) tests have been used with routine tests for the assessment of semen quality. This is the first study in which the comparison of potential fertility estimation of fore-mention three tests was performed. Bull semen samples were divided into two fertility groups (high: n=3, low: n=3), according to their post-insemination NRR (non-return rate). Prior to the tests, post-thawed spermatological characteristics were assessed after which HOS, TS and mCMP tests were carried out. In the HOS test, the ratio of swollen cells, in the TS test the motility, and in the mCMP test the number of spermatozoa penetrating the cervical mucus, were examined. The relationship between the tests and fertility was also evaluated. HOS test was carried out according to different incubation times and temperatures (37 degrees C 60 min/41 degrees C 15 min/41 degrees C 30 min/46 degrees C 15 min/46 degrees C 30 min). For TS test, samples were subjected to various temperatures for different periods (no incubation (37 degrees C)/41 degrees C 15 min/41 degrees C 30 min/46 degrees C 15 min/46 degrees C 30 min). The mCMP test were subjected to various temperatures for the same period (37 degrees C 15 min/41 degrees C 15 min). In this study, post-thawed motility was found to be similar in high and low fertility groups. However, it has been determined that acrosomal (p<0.01) and other morphological defects (p<0.05) were low in the high fertility group. When HOS test was carried out at 37 degrees C, no difference was observed between the bulls with high and low fertility, but at 41 and 46 degrees C, results of high fertility group were significantly higher than those of low fertility group (p<0.01). Similarly in TS test, the progressive motility rates of high fertility bulls was higher after thermal practices at 41 and 46 degrees C (p<0.01). In mCMP test, at 37 degrees C, the number of cells that had penetrated was similar. However, significant differences were observed in the incubation at 41 degrees C (p<0.01). It has been concluded that for the estimation of potential fertility of bulls, HOS, TS and mCMP tests, in combination with routine spermatological tests can be used and the use of further penetration distance range (PDR2) in mCMP test and higher temperatures such as 41 degrees C instead of 37 degrees C, during the incubations in the afore-mentioned performance tests, is more determinative.

Relationships among frozen-thawed sperm characteristics assessed via the routine semen analysis, sperm functional tests and fertility of bulls in an artificial insemination program

Frozen semen specimens from 22 Holstein bulls representing a wide range of field fertility levels or nonreturn rates (NRR) were used in this study. Semen specimens were thawed at 37 degrees C for a minimum of 30 sec, followed by assessment via a routine semen analysis (RSA) and other sperm functional tests. The RSA was performed by assessing sperm count, motility and morphological characteristics. Other sperm functional tests were performed by assessing the acrosomal membrane integrity, sperm penetration into the cervical mucus and the sperm membrane functional integrity. Following assessment of sperm characteristics, the fertility data of the various bulls were compared to the RSA and the functional tests results. Bulls of high and low fertility were similar in terms of sperm count and progressive motility (P > 0.05). Other characteristics measured by the RSA and functional tests were significantly higher in high fertility bulls (P < 0.05). Correlation coefficients among the various sperm characteristics and fertility of bulls were highly significant (P < 0.01). The highest correlation coefficients between sperm characteristics and fertility were obtained for motility (r = 0.53; P < 0.01), normal morphology (r = 0.59; P < 0.01) and swollen spermatozoa (r = 0.57; P < 0.01). Analysis of specific sperm swelling patterns showed that those patterns considered to reflect maximal sperm swelling were indicative of high fertility.

Combination of hypoosmotic swelling/eosin Y test for sperm membrane integrity evaluation: correlations with other sperm parameters to predict ICSI cycles

The objective of our study was to evaluate the accuracy of the combination of hypoosmotic swelling (HOS) and eosin Y (Ey) exclusion tests to predict the ICSI cycles' outcome and its correlations with other sperm parameters. The functional and structural integrity of sperm membrane was evaluated with the combined HOS/Ey test in 95 ICSI cycles and the results were correlated with other sperm parameters, including concentration, motility, strict morphology, and total motile sperm count. The combined HOS/Ey test was evaluated for the prediction of the ICSI cycles' outcome parameters including fertilization, cleavage, and pregnancy rates. The HOS/Ey test presented significant relationships with concentration, motility, and strict morphology (p < 0,0001) but it couldn't predict the fertilization, cleavage, and pregnancy outcomes of ICSI cycles. The combined HOS/Ey test has strong correlations with motility and strict morphology parameters of sperm samples but is not sufficiently sensitive to estimate the outcome of ICSI cycles.

Prognostic value of spermatological parameters as predictors of in vitro fertility of frozen-thawed bull semen

Cryopreservation imposes irreversible damage to sperm membranes, such as swelling and disruption of plasma and acrosome membranes, changes in membrane fluidity, altered influx of calcium, and changes in enzyme activity. Morphological integrity of the sperm plasma membrane has been widely studied using different techniques, including exposure of spermatozoa to hypoosmotic solutions (provides information concerning the biochemical activity of the sperm tail membrane), supravital test using eosin stain (yields information regarding sperm head membrane integrity), and Trypan-blue Giemsa stain (TBG; reveals both sperm plasma membrane and acrosome integrity). The objective of this study was to combine these tests in order to provide information about the integrity of the whole sperm surface, as well as acrosome status, and determine if the results of these tests were associated with sperm in vitro fertilizing ability. Stepwise regression analyses yielded a model in which fertility (maintain variable) was expressed as a combination of the results of different spermatological parameters (independent variables). The results of a test combining supravital eosin staining of samples previously submitted to hypoosmotic swelling test (STHOS) accounted for the greatest proportion of variation in fertilization rates (78%). Inclusion of the results of dual staining with TBG increased the proportion of variation in fertility rate that could be accounted for to 82%. Therefore, sperm plasma membrane integrity and function, and acrosome integrity can be considered important variables for normal sperm function and STHOST and TBG could be used for the prognosis of the potential fertility of bovine semen samples used for IVF or AI.

Assessment of sperm functional competence and sperm-egg interaction

A precise understanding in the functional competence of mammalian sperm is essential to generate clinical advances for the treatment of infertility and novel contraceptive strategies. The fundamental knowledge on the controlling parameters for spermatozoal activation process will help in the identifying the causes in fertilization failure due to male factor as well as in developing male contraceptive methodologies. The defects in the sperm-egg interaction seem to be one of the controlling mechanisms, however, none of the presently available methods for the evaluation of the fertilizing ability of sperm precisely indicates the reason for the failure or the success of sperm entry into egg. Adequate number of motile spermatozoa with normal morphology and timely occurrence of acrosome reaction are presumably the major prerequisites for the penetration through the egg investments. The present communication briefly reviews some of the main features of mammalian sperm which control the success or the failure of fertilization and existing clinical methods indicating the lack of fundamental knowledge on the sub-cellular and molecular aspects of this unique and species-specific cell-cell interaction.

Bull semen in vitro fertility after cryopreservation using egg yolk LDL: a comparison with Optidyl®, a commercial egg yolk extender

Low-density lipoproteins (LDL) have been previously isolated and identified as the cryoprotective fraction of yolk. The effect of LDL on sperm motility after freezing-thawing has been reported, but no study has been made to assess the effect of LDL on bull semen fertility. The aim of this study was to evaluate the fertility of bull semen cryopreserved in the presence of LDL. Motility of semen cryopreserved in LDL was analyzed and compared to semen cryopreserved with Optidyl, a commercial extender containing egg yolk. To evaluate the fertilizing ability of semen, we used in vitro fertilization test, whereas acrosome and plasma membrane integrity were also evaluated. The percentage of motile spermatozoa was two fold higher after freezing in LDL than in Optidyl 54.4% versus 30.2% (P < 0.05). The cleavage rate was significantly higher after fertilization with semen frozen in LDL than with Optidyl 63.0% versus 54.8% (P < 0.05). No significant difference was observed on the blastocyst rate after in vitro culture. Integrity of the acrosome and the plasma membrane were maintained in both extenders. In conclusion, LDL preserve bull semen quality and fertilizing ability, allowing also better semen motility, after the freeze-thaw process.

Four subpopulations of boar spermatozoa defined according to their response to the short hypoosmotic swelling test and acrosome status during incubation at 37 °C

This study was designed to confirm the previously observed relationship between response to the short hypoosmotic swelling test (sHOST) and acrosome resistance in boar spermatozoa. Ejaculates from 22 boars were incubated in a water bath at 37 degrees C for 2h. During the incubation period, samples were taken at 5, 20, 40, 60, 90 and 120 min and subjected to the sHOST. sHOST responses (positive HP-negative HN) and acrosomal status (normal or intact NA-damaged DA) were evaluated in 100 spermatozoa corresponding to each ejaculate and incubation time, and the results used to establish four subpopulations: HPNA, HPDA, HNNA and HNDA. Over the entire incubation period, the sHOST positive subpopulation with damaged acrosomes, HPDA, was significantly smaller than the sHOST negative, damaged acrosome subpopulation, HNDA (P<0.001). Further, proportions of HPDA spermatozoa remained stable throughout this period while the HNDA subpopulation showed a significant increase (P<0.001) from the start to the end of incubation. These results confirm the high resistance of the plasma membrane of HP spermatozoa allowing the persistence of a higher number of intact acrosomes over time, compared to HN spermatozoa. Characterising this HPNA subpopulation may help the evaluation of ejaculate quality.

The predictive value of semen analysis in the evaluation of stallion fertility

Pregnancy rates in managed horse populations depend on the innate fertility of the mares and stallions involved and on the quality of breeding management. Of course, because a single stallion usually mates many mares, stallion fertility is a critical factor in the overall success of a breeding program. Unfortunately, accurate evaluation of stallion fertility per se requires a large number of normal mares to be mated and is necessarily retrospective. Rather, the ideal is to predict fertility in advance of the stallion's breeding career, and this is currently attempted by way of a thorough physical examination and a routine analysis of semen quality. However, while such a 'breeding soundness examination' identifies stallions that clearly lack the capacity for adequate fertility, it is of limited use for predicting the level of fertility and fails to identify some seriously sub-fertile animals. Similarly, while various sperm function tests (e.g., sperm head morphometry, the hypoosmotic swelling test, glass wool-sephadex filtration, progesterone receptor exposure) have been shown to correlate fairly well with fertility in the field, most examine only a single or a narrow range of the attributes that a sperm must possess if it is to fertilize an oocyte in vivo, and are thus more useful for identifying specific causes of sub-fertility than for predicting the level of fertility. On the other hand, combining the results of the various sperm function tests does improve the reliability of fertility estimation and current research is therefore concentrated on identifying a range of tests that covers as many important sperm attributes as possible but that can be performed rapidly and cheaply. In this respect, flow-cytometry has proven to be an ideal tool because it allows the objective, rapid and simultaneous analysis of a number of properties in a large number of sperm. Moreover, stains are available for an increasing range of sperm characteristics including viability, capacitation and acrosome status, mitochondrial activity and chromatin integrity. Flow-cytometric analysis of sperm with appropriate probes thus offers considerable promise for the prediction of stallion fertility.

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.

Motion characteristics of Murrah buffalo bull spermatozoa in various seasons and its relationship with functional integrity of the plasmallema

Semen was collected from six adult (3.5-7-year-old) Murrah buffalo bulls at weekly intervals for 1 year and evaluated for routine parameters, motion characteristics, reactivity in hypoosmotic solution, and acrosomal and other morphological abnormalities of the spermatozoa. The overall motility (MOT), straight line velocity (VSL), curvilinear velocity (VCL), linearity (LIN), lateral head displacement (ALH) and average path velocity (VAP) were 66.85+/-2.79%, 26.58+/-0.24 and 107.07+/-1.47 microm/s, 26.91+/-0.01%, 11.19+/-0.09 and 61.78+/-2.79 microm/s, respectively. Significant seasonal variation was observed in sperm kinematics and hypoosmotic swelling (HOS) reactivity. Except for LIN, the mean values of sperm dynamics were higher during summer and rainy season and significantly lower in winter season. Sperm kinematics showed significant (P<0.01) positive correlation (r=0.25-0.60) with plasmallemal integrity. Ejaculates with less than 50% HOS-reactive spermatozoa had significantly lowered MOT, VSL, VCL and VAP as compared to the ejaculates with >50% HOS-positive spermatozoa. No significant difference was observed in sperm kinematics among the ejaculates having 50-70% and >70% HOS-reactive spermatozoa. The trend of motion dynamics of the spermatozoa with respect to HOS reactivity was similar in all the three seasons (summer, rainy and winter). The results indicate that ejaculates having more than 50% of HOS-reactive sperm show a higher magnitude of sperm kinematics compared to ejaculates having less than 50% HOS-positive spermatozoa.

Relationship between the characteristics of epididymal red deer spermatozoa and penetrability into zona-free hamster ova

A heterologous (zona-free hamster oocytes) in vitro fertilization (IVF) system was used to evaluate the relationship between sperm factors and penetration capacity of epididymal red deer spermatozoa. The sperm parameters evaluated in 36 sperm samples obtained postmortem from stags selectively shot during the rutting season were sperm motility, functional integrity of plasma membrane by means of the hypo-osmotic swelling test (HOST), and, simultaneously, viability and acrosomal status via a triple-stain technique. Zona-free hamster oocytes were used to evaluate the capacity of the different sperm assays to predict in vitro penetration. In order to increase the variability in sperm quality, we recovered samples from stags at different intervals between the death of the male and the collection of the genitalia. All measures of sperm quality declined progressively (P <.001) with increasing intervals between death and sample collection. In addition, many sperm parameters were related to penetration ability in vitro. Subsequently, sperm samples were rearranged in 2 categories according to the interval that had elapsed between death and the collection of the genitalia (group 1, short interval = 0-12 h; group 2, large interval = 18-40 hours). When samples were grouped, less correlation achieved significance, especially for group 1, than when samples were not divided. Also, correlation between the number of sperm per oocyte and sperm parameters for group 1, which had the highest values of sperm quality, failed to reach significance. It is concluded that the classical parameters accepted in assessing the viability of deer spermatozoa can be good predictors of the penetrating ability of the spermatozoa when satisfactory in vitro conditions are used for the development of the IVF system. Also, this study demonstrates that compatible heterologous gamete interaction allows thorough assessment of sperm function in a wild deer.

Prognosis for sperm fertilizability: analysis of different variables in men

An overview of various sperm tests is presented. The standard semen analysis obtained by most clinicians evaluating infertility usually consists of sperm concentration, percent motility, quality of motility, and sperm morphology. Unfortunately, unless the motile density is extremely low, the count and motility are not good prognosticators of fertility potential. Values above the norm for normal fertile couples unfortunately cannot reliably predict normal fertility potential. It is important to find sperm tests that are easy to perform, are relatively inexpensive, and provide an accurate prognosis. Strict morphology was hoped to be such a tool with initial optimism that it was far superior to standard morphology. Unfortunately, this test also failed to be the ideal inexpensive prognostic test after further evaluation. One test that is inexpensive and highly correlates with fertilizability is the presence of antisperm antibodies since their presence frequently does not alter count, motility, or morphology. This test should be performed as part of the routine semen analysis. Other tests highly correlate with the achievement of pregnancy and are simple and inexpensive to perform, but, interestingly, do not correlate with fertilizability. These include the hypoosmotic swelling test (HOST) and the sperm stress test. Abnormalities in these tests imply a different abnormality of sperm that leads to conception failure and that is the transfer of a toxic factor from the sperm to oocyte to embryo that prevents the embryo from implanting. Certainly, the simple, inexpensive HOST should be performed routinely. Other tests of sperm function, e.g., sperm penetration assay, sperm zona pellucida binding assay, and acrosome reaction, have their definite place in the evaluation of the infertile male. However, because they are expensive and difficulty to perform they lend themselves to certain specific circumstances but not to routine testing.

A short hypoosmotic swelling test for the prediction of boar sperm fertility

This study was designed to explore the relationship between the ejaculate response to a hypoosmotic swelling test (HOST) and in vivo fertility in a group of 38 boars The hypoosmotic test used was a modification of the HOST that involves a shorter incubation time (5 vs 120 min) and lower osmotic pressure (75 vs 150 mOsm/kg). Ejaculates containing less than 20% abnormal spermatozoa were selected and checked for percentage of motility, percentage of normal acrosomes, percentage of short ORT and percentage of cells showing positive short HOST (sHOST) results Two hundred eightyeight sows were inseminated to obtain in vivo fertility and prolificacy data. No differences were shown between technicians in the sHOST results obtained. Significant differences were recorded between boars in sHOST results (p < 0.002). Only the sHOST result presented a significant correlation with in vivo fertility (r = 0.43, p < 0.01). Short HOST data significantly improved fertility prediction of routine semen analysis tests. Unlike motility and acrosomal status, sHOST values showed a significant decrease when fresh ejaculates (37 degrees C) were stored for 24 h at 15 degrees C, indicating possible damage due to cold shock.

Some semen abnormalities may cause infertility by impairing implantation rather than fertilization

The hypo-osmotic swelling (HOS) test measures the functional integrity of the sperm membrane. Although, the sperm membrane is essential for the fertilization of oocytes, several clinical studies suggest that abnormally low HOS test scores do not predict poor or failed fertilization in human in-vitro fertilization trials. However, in-vivo and in-vitro studies clearly demonstrate that a low HOS score is associated with poor pregnancy rates suggesting this sperm defect causes implantation problems rather than fertilization problems. The problem of implantation could be caused by the supernumerary sperm attached to the zona pellucida. Supporting evidence for this theory was demonstrated by finding high pregnancy and implantation rates despite low HOS scores following intracytoplasmic sperm injection which avoids the presence of supernumerary sperm on the zona pellucida. These data thus support theories that some sperm abnormalities may reduce fertility potential by causing implantation disorders rather than problems with fertilization.

Assessing equine sperm-membrane integrity

The swelling of cells in a hypo-osmotic medium has been described as an important criterion for assessing the functional integrity of the sperm plasma membrane. The resistance of equine spermatozoa to osmolarity changes was studied by extending 98 semen samples collected from nine stallions in media at five osmolarities (300, 200, 150, 100, and 50 mOsmol l(-1)). The response of the cells was measured by the spermatocrit technique and eosin staining. Spermatocrit determines the increase on spermatozoal volume under hypo-osmotic conditions, a sign of functional integrity of sperm plasma membrane, whereas the eosin staining evaluates the viability of spermatozoa. A significant positive correlation (P<0.01) was observed between spermatocrit values and percentage of eosin-unstained cells. Spermatocrit measurements and eosin staining proved to be useful methods to evaluate the integrity of sperm plasma membrane under hypo-osmotic conditions and could be used as an additional criterion to predict semen preservation ability.

Hypoosmotic swelling (HOS) as a screening

Semen from 5 Piedmontese bulls was subjected to the hypoosmotic swelling (HOS) test in order to determine if the results could be correlated to the fertilizing capacity in vitro. Semen was routinely prepared for in vitro fertilization (IVF), with aliquots being sampled after thawing, after separation on a Percoll gradient and after capacitation in a medium containing heparin. The aliquots were added to a fructose-sodium citrate hypoosmotic solution (100 mOsm) and incubated at 37 degrees C for 5 min. At least 200 spermatozoa were observed at x 400 and classified according to the presence or the absence of a swollen tail. After capacitation, spermatozoa were used to fertilize in vitro-matured bovine oocytes (1.5 x10(6) cells/mL); IVF was performed in Fert-TALP medium supplemented with 6 mg/mL BSA and 10 microL/mL heparin in a humidified atmosphere with 5% CO2 and 5% oxygen. Presumptive zygotes were cultured in SOF medium supplemented with 8 mg/mL BSA and amino acids. There were no significant differences in the in vitro fertility of the bulls, but a significant difference was found between bulls in the response to the HOS test. The 3 assays were significantly correlated, while no significant correlation was observed between the percentage of swollen spermatozoa and in vitro fertility. The HOS test does not appear to be sufficiently sensitive to discriminate between semen samples of intermediate fertility like those used in this preliminary research.

Failure of fertilization after intracytoplasmic sperm injection in a patient with Kartagener's syndrome and totally immotile spermatozoa: case report

Patients with Kartagener's syndrome (KS) are invariably infertile with totally immotile spermatozoa. Intracytoplasmic sperm injection (ICSI) is considered to be the treatment of choice for patients with immotile spermatozoa. We report the second KS case in the literature from whom immotile spermatozoa from the ejaculate failed to fertilize mature oocytes after ICSI. The role of micromanipulation in the treatment of KS patients is discussed.

Effect of freeze-thawing procedure on chromatin stability, morphological alteration and membrane integrity of human spermatozoa in fertile and subfertile men

Cryopreservation is known to impair sperm motility and decrease the fertilization rate by detrimental effects on acrosomal structure and acrosin activity. However, the consequences of cryopreservation on the integrity of the sperm nucleus, chromatin stability and centrosome are less clear. The present study was designed to determine the effect of the freeze-thawing procedure on chromatin condensation (aniline blue staining) and the morphology (strict criteria) and membrane integrity of human spermatozoa. The structural and functional characteristics of the sperm plasma membrane were measured by the eosin-test and hypo-osmotic swelling test which were done separately. Sperm cryopreservation was performed on semen samples from two groups of men classified as fertile (n = 20) and subfertile (n = 72), based on their reproductive history and semen analysis according to WHO guidelines. The mean percentage of condensed chromatin, morphologically normal spermatozoa and membrane integrity in all semen samples investigated (n = 92) decreased significantly (p = 0.0001) after freeze-thawing, in comparison to the value observed prior to freezing. By comparing the semen samples between fertile and subfertile patients, significantly (p = 0.0009) greater damage was demonstrated in the subfertile than in the fertile group. Furthermore, no significant difference was observed between the two groups with regard to the morphological alteration and structural as well as functional damage of the sperm membrane. In conclusion, the freeze-thawing procedure significantly affects chromatin structure and sperm morphology, especially in the head and the tail regions, and this may explain the lower fertilization rate and IVF/ICSI outcome when frozen-thawed spermatozoa are used. In addition, this study demonstrates that chromatin condensation is a sensitive parameter for the evaluation of cryodamage of semen samples from fertile and subfertile patients, though subfertile patients with very poor semen characteristics have yet to be studied. It is therefore recommended that chromatin condensation be used as an additional parameter for the assessment of sperm quality after freeze-thawing.

Evaluation of the effects of different trypsin treatments on semen quality after BHV-1 inactivation, and a comparison of the results before and after freezing, assessed by a computer image analyzer

Semen infected experimentally with infectious bovine rhinotracheitis virus (BHV-1) was treated with trypsin at concentrations of 0.30%, 0.25% and 0.15%, with or without (w or w/o) trypsin inhibitor in order to render the semen virus free. The trypsin treatments (at 0.30% and 0.25% by concentration) inactivating the virus up to 10(4) TCID50/ml, and its effects on semen quality were assessed weekly from the 1st to 20th week after being frozen. The following parameters were determined using a computerized semen analysis system (Hamilton Thorn motility analyzer, HTM): total motility, progressive motility and linearity of sperm cells. The results showed that the total and progressive motility of sperm cells were reduced in frozen/thawed semen, principally in the semen treated with trypsin at concentrations of 0.30%. Moreover, the plasma membranes were damaged by trypsin treatments (0.30% by concentration), as determined by the hypoosmotic swelling test (HOS test). These findings suggest that trypsin treatments were effective against the virus however the effects on semen quality and the possibility of a decrease in semen fertility were clear. Trypsin treatment could be recommended at a maximum concentration of 0.25% (w/o trypsin inhibitor) on semen with a high concentration and high motility values of spermatozoa before freezing.

Semen analysis and antisperm antibody

Evaluation of the fertilizing potential of sperm is an important procedure in in vitro fertilization and embryo transfer (IVF-ET) clinic, in order to avoid performing invalid conventional IVF-ET or unnecessary intracytoplasmic sperm injection (ICSI). However, none of the standard semen parameters are reliable indices in predicting IVF outcome. The test examining sperm-zona interaction is the best present method, though the short supply of the human zona component should be solved. IVF-ET treatment is useful for pregnancy in women having sperm immobilizing antibodies because it avoids exposing sperms to antibodies that block fertilization. ICSI should be used in immunologically infertile men diagnosed by specific method to demonstrate the in vivo exposure of sperms to antisperm autoantibodies that block fertilization.

Comparisons of sperm quality, morphometry and function among human sperm populations recovered via SpermPrep II filtration, swim-up and Percoll density gradient methods

The purpose of this study was to compare the morphology/morphometry and fertilizing capacity of human spermatozoa recovered via swim-up method, Percoll density gradient method, and SpermPrep II filtration method. Thirty-three ejaculates were equally divided into 2 aliquots. Aliquot 1 was processed via the direct swim-up method, whereas aliquot 2 was filtered via a SpermPrep II column. The Percoll density gradient method was compared with the SpermPrep II method in a similar protocol using 43 ejaculates. Sperm populations recovered via the SpermPrep II filtration method showed significantly higher hypoosmotic swelling test results, acrosin profiles, and percentage of hyperactivated spermatozoa than sperm fractions recovered by the swim-up method. Furthermore, significant differences were found in most of sperm morphometric parameters between the above sperm populations. However, sperm fractions recovered via the SpermPrep II method did not show significantly different values for these same tests and for most of sperm morphometric parameters compared to the Percoll density gradient method. These results suggest that the SpermPrep II filtration and Percoll density gradient method are equally efficient in isolating sperm subpopulations with better functional parameters than the swimup method.

Reactive oxygen species generation by seminal cells during cryopreservation

OBJECTIVES

To test the hypothesis that conventionally used procedures for semen cryopreservation may cause an increase in the production of reactive oxygen species (ROS) by sperm or by seminal leukocytes, which may contribute to poor sperm function following cryopreservation.

METHODS

Eighteen semen specimens with normal parameters from healthy male donors 22 to 40 years of age were each divided into two portions. The first portion was combined 1:1 with Test Yolk Buffer-Glycerol Freezing Medium and was frozen by gradual cooling into liquid nitrogen (-196 degrees C). The second portion was washed and the cells were resuspended in Sperm Washing Medium (SWM) and incubated at room temperature to serve as controls. After a period of treatment, frozen samples were thawed and semen cells were washed and resuspended in SWM. ROS generation by semen cells from each treatment group was measured on a luminometer. Sperm motility, sperm viability, and sperm membrane integrity were also measured in both control and freeze-thaw samples. To further assess ROS generation by semen cells during the cooling process, aliquots of washed semen cells and purified polymorphonuclear leukocytes (PMNs) were incubated separately at different temperature conditions (37 degrees C, 22 degrees C, 4 degrees C, and -20 degrees C). ROS activity in each treatment group was measured and compared with each other.

RESULTS

In both semen cells and PMNs, ROS activity increased significantly during the cooling process. The highest ROS levels were recorded in both groups when cooled to 4 degrees C. The ROS levels were extremely low in samples cooled to -20 degrees C and in freeze-thaw samples, probably due to marked loss of cell viability.

CONCLUSIONS

Gradual reduction of temperature during the process of semen cryopreservation can cause a significant ROS generation by semen cells. ROS is particularly elevated during cooling if the semen sample is contaminated by more than 0.5 x 10(6) leukocytes. Removal of leukocytes from semen samples or treatment with antioxidants prior to cryopreservation may improve sperm viability and function.