One-step warming does not affect the in vitro viability and cryosurvival of cryotop-vitrified donkey embryos

The objective of this study was to compare the effects of two warming protocols (three-step vs. one-step dilution) on embryo quality, post-warming embryo survival and embryo cell viability of donkey embryos vitrified by the Cryotop method. Twenty, Day 7-8, grade 1-2 donkey embryos were measured, morphologically evaluated and vitrified using the Cryotop technique. Embryos were then randomly warmed using two different warming procedures: (i) W3 (three-step dilution; n = 11): embryos were warmed in 1 M, 0.5 M and 0 M sucrose, and (ii) W1/0.5 (one-step dilution; n = 9): embryos were warmed directly in 0.5 M sucrose. After 3 and 24 h of warming, the embryos were measured and evaluated for their morphology, developmental stage and viability (Propidium Iodide-Hoechst 33,342 dyes). Although both treatments decreased embryo quality after warming (P < 0.05), no significant differences (P > 0.05) were observed between protocols in terms of post-warming embryo quality, diameter and embryo survival. Greater percentages of dead cells (P < 0.001) were observed when embryos were warmed directly in 0.5 M sucrose (one-step dilution) when compared to the three-step protocol. The percentage of ruptured embryos was 27.3% and 0% in W3 and W1/0.5 protocols (P = 0.0893), respectively. In conclusion, warming Cryotop-vitrified donkey embryos directly in 0.5 M sucrose had no negative effects on embryo quality and post-warming embryo survival. Moreover, one-step protocol may help to prevent rupture when donkey embryos warmed directly in 0.5 M sucrose. These results observed in vitro must be verified by embryo transfer.

28 Short equilibration improves vitrification of invitro-produced bovine embryos using VitTrans device

For the successful application of vitrification technology to field conditions, the procedures for the warming and transfer of the cryopreserved bovine embryos should be as simple as possible. The device VitTrans, designed by our group, enables warming/dilution of embryos and their transfer directly to recipient females in field conditions (Morato and Mogas 2014 Cryobiology 68, 288). VitTrans vitrification protocol consists of an incubation in equilibration solution during 12min followed by an exposure of 40s to vitrification solution. However, there are other reports using similar vitrification devices where equilibration length is shorter than ours. This study aimed to improve VitTrans methodology by comparing two vitrification protocols: short equilibration (SE) and long equilibration (LE). A total of 63 invitro-produced Day 7 blastocysts (IETS stage code 7) were randomly placed in an equilibration solution with 7.5% ethylene glycol + 7.5% dimethyl sulfoxide in holding medium (tissue culture medium-199 HEPES + 20% fetal calf serum) for either 3min (SE) or 12min (LE). Then, blastocysts were transferred to vitrification solution (15% ethylene glycol + 15% dimethyl sulfoxide + 0.5M sucrose in holding medium) for 40s, loaded onto the VitTrans device, plunged into liquid nitrogen, and covered with a 0.5mL straw. Fresh nonvitrified blastocysts (n=30) were set as control. For warming, the VitTrans was quickly submerged into a water bath at 45°C, while a syringe containing 0.3mL of diluting solution (0.5M sucrose in holding medium) at 45°C was injected through the hollow of the device. Blastocysts were then transferred to synthetic oviductal fluid medium and cultured for 24h at 38.5% in a 5% CO2 and 5% O2 environment in a humidified atmosphere. Re-expansion rates were recorded 3 and 24h after warming. Blastocysts were fixed and stained with SOX2 (Invitrogen) for inner cell mass (ICM) count, TUNEL (Roche) for apoptosis index assessment, and DAPI (Vector Laboratories) for total cell count (TCC). Images were captured using a Leica TCS SP5 confocal microscope (Leica Microsystems) and examined with Imaris 9.2 software (Oxford Instruments). Blastocyst survival rates were compared between groups using chi-squared test. Blastocyst TCC, ICM count, and apoptosis indices were analysed using analysis of variance. Significance was set at P ≤ 0.05. No differences were observed in re-expansion rate at 3h postwarming (61.3 and 59.4% for SE and LE, respectively). However, significantly higher re-expansion rates were found after 24h of culture for the blastocysts of the SE group (74.2%) when compared with the blastocysts of the LE group (65.7%). Blastocysts vitrified using the LE protocol produced the lowest TCC (115±5.9; P ≤ 0.05), whereas TCC of the SE (152±9.7) and fresh control (138±8.6) treatments were similar. No differences were found in ICM count among groups. Nevertheless, apoptosis index was higher (P ≤ 0.05) in both vitrification groups when compared with fresh control. These results indicate that short equilibration vitrification not only improves VitTrans outcomes but adds efficiency by taking less time to perform. Supported by MCIU, Spain (Project AGL2016-79802-P and Grant BES-2017-081962).

33 Assessment of spindle morphology and reactive oxygen species production after vitrification of bovine oocytes following invitro maturation in the presence of glutathione ethyl ester

Oocyte cryopreservation by vitrification affects spindle integrity and causes oxidative stress induced by reactive oxygen species (ROS). Glutathione (GSH) ensures the correct assembly of microtubules, prevents ROS from attacking tubulin assembly, and ensures normal spindle function during meiosis. We hypothesised that addition of GSH ethyl ester (GSH-OEt), a cell-permeable GSH donor, to IVM medium before vitrification may improve oocyte cryotolerance by maintaining spindle morphology and preventing ROS production. For the IVM, viable cumulus-oocyte complexes were randomly distributed into two groups: 1) control: conventional IVM media with tissue culture medium-199 + 20% fetal calf serum + epidermal growth factor and 2) GSH-OEt: IVM medium supplemented with 5mM GSH-OEt at 38.5°C in a 5% CO2 humidified air atmosphere. After 22h of IVM, half of the oocytes from each group were vitrified/warmed using the Cryotop method (Kitazato Corp.). After 24h of IVM, oocytes were denuded, fixed, and microtubule and chromosome distribution were analysed by immunofluorescence. To measure ROS, oocytes were denuded and incubated in 5μM 2′,7′-dichlorodihydrofluorescein diacetate. Fluorescence was acquired, and resulting images were quantified with ImageJ software. A linear mixed effect followed by a pairwise comparison test (Tukey adjustment) were performed to analyse differences in meiotic spindle configuration and ROS production (P&lt;0.05). No significant differences in percentages of MII or normal spindle configuration were observed among treatments. Treatment with GSH-OEt before vitrification resulted in similar percentages of abnormal spindle configuration to control oocytes, whereas vitrified oocytes showed significantly higher percentages of abnormal spindle configuration relative with control oocytes (Table 1). When the content of ROS was measured, vitrification resulted in significantly higher levels (15.1E+06±1.2E+06; P&lt;0.05) when compared with other treatments. However, oocytes vitrified after IVM with GSH-OEt (11.8E+06±0.6E+06) showed similar ROS levels to control (10.7E+06±0.2E+06) and GSH-OEt (10.0E+06±0.1E+06) groups. In conclusion, addition of GSH-OEt to IVM before vitrification did not have detrimental effects on spindle morphology and was able to reduce ROS content. Further experiments are warranted to assess whether the addition of GSH-OEt to IVM medium can improve oocyte development competence after vitrification. Table 1.Assessment of spindle morphology after oocyte vitrification (VIT) following IVM in the presence of glutathione ethyl ester (GSH-OEt) Item n MII (%) Spindle configuration (%) Chromosome distribution (%) Normal Abnormal Absent Dispersed Decondensed Absent Control 127 79.4±92 74.1±4.4 16.2±5.6a 9.7±1.1 16.2±3.8 9.7±1.1 0 GSH-OEt 113 76.5±6.5 65.6±5.7 26.2±9.0ab 8.1±4.3 19.5±2.6 13.7±3.0 1.1±1.1 VIT 71 60.0±5.6 54.8±7.8 32.7±10.8b 12.4±1.4 34.4±8.7 10.7±6.4 0 GSH-OEt VIT 53 57.4±10.7 58.5±8.8 31.1±9.3ab 10.4±5.8 34.8±5.6 6.7±6.7 0 a,bDifferent superscripts indicate significant differences (P&lt;0.05). *Percentage referred to the total number of oocytes at MII. This work was supported by MCIU, Spain (AGL2016-79802-P) and Generalitat de Catalunya (García-Martínez, 2017_FI_00451).

The cryoprotective effect of Ficoll 70 on the post-warming survival and quality of Cryotop-vitrified donkey embryos

Many domestic donkey breeds are at risk of extinction, there is a critical urgency for genome resource banking. In the present study, we examined whether the use of Ficoll 70 added to the vitrification medium containing ethylene glycol (EG), dimethyl sulfoxide (DMSO) and sucrose improves the cryotolerance of donkey in vivo derived embryos. Day 7-8, grade 1-2 donkey embryos were measured and morphologically evaluated and then vitrified-warmed using the Cryotop technique. Before vitrification, embryos were randomly distributed into two groups: (i) VS1 (n = 14): vitrified using 15% EG + 15% DMSO + 0.5 M sucrose; and (ii) VS2 (n = 10): vitrified in the same medium supplemented also with 18% of Ficoll 70. After 24 h of warming, the embryos were measured and evaluated for their morphology, development and viability (Propidium Iodide-Hoechst 33342 dyes). Post-warming survival was numerically higher but not significantly different (P > 0.05) when embryos were vitrified in VS2 (70%) compared to VS1 (57.1%). Embryo rupture was only observed in the VS1 group (21.4%, 3/14). Higher embryo diameter was observed in all groups after 24 h culture (P < 0.05). No significant differences (P > 0.05) were observed among treatments in terms of percentages of cell death. These results demonstrate that the addition of Ficoll 70 to the vitrification medium is not a pre-requisite for successful vitrification of donkey embryos. However, its addition seems to enhance some of the post-warming embryo quality characteristics. Since no statistically significant evidence was found, further studies should be conducted in order to confirm our findings.

12 Effect of additional prostaglandin F2α during the Ovsynch protocol applied in different postpartum intervals in lactating dairy cows: Preliminary results

Timed AI (TAI) programs have been developed to increase the service risk. However, when Ovsynch is used as a synchronization protocol, lack of regression of the corpus luteum after prostaglandin F2α (PGF) administration has been demonstrated, leading to reductions in fertility. In this way, a second PGF administration might increase the frequency of achieving complete luteolysis. This study aimed to evaluate the effect of an additional treatment with PGF on fertility when an Ovsynch synchronization protocol was applied at different postpartum intervals. Multiparous high-production dairy cows (n=471) of a commercial farm were stratified by postpartum intervals [&lt;120 (n=136), 120-150 (n=131), 150-180 (n=92), 180-210 (n=52), and &gt;210 days (n=60)] and randomly allocated to receive either the Ovsynch (n=108) or Ovsynch with second PGF protocol (n=243). Cows inseminated 12h after observed heat detection (AI) served as a control (n=120). The Ovsynch protocol consisted of an injection of gonadotropin-releasing hormone (100 µg; Fertagyl®, Intervet, Millsboro, MD, USA) on Day 0, an injection of PGF (0.5 mg; Estrumate®, Schering-Plough Animal Health, Montréal, QC, Canada) on Day 7, another injection of gonadotropin-releasing hormone (100µg) on Day 9, and timed insemination on Day 10. The Ovsynch with second PGF protocol consisted of the same hormone injection schedule as the Ovsynch protocol, but a second injection of PGF (0.5 mg; Estrumate®) was administered 24h after the first PGF. Data were analysed using the chi-square test. The level of significance was taken as P&lt;0.05. When data were pooled at 120 to 150 days of postpartum interval, pregnancy rate was higher, but not significantly different (P&gt;0.05), for cows that received the Ovsynch (37.5%, n=32) or Ovsynch with second PGF protocol (33.8%, n=77) compared to nonsynchronized cows (22.8%, n=22). After 180 days of postpartum interval, Ovsynch with second PGF protocol triggered pregnancy rates similar to those of nonsynchronized cows (33.3%, n=21 and 28.6%, n=14), whereas the Ovsynch protocol resulted in lower percentages (11.8%, n=17; P&gt;0.05). Similar pregnancy rates (P&gt;0.05) were observed when TAI protocols were administered before 120 days (26.5 and 30.2% for Ovsynch and Ovsynch with second PGF, respectively) or between 150 and 180 postpartum days (31.8 and 33.9% for Ovsynch and Ovsynch with second PGF, respectively) compared with AI cows (25.7 and 28.8% for &lt;120 days and between 150 and 180 postpartum days, respectively). These preliminary results showed a tendency of a better pregnancy rate when both TAI synchronization protocols were applied between 120 and 150 postpartum days when compared with AI. Also, the application of a second dose of PGF seems recommendable when the Ovsynch protocol is used to synchronize cows of &gt;180 postpartum days. Ongoing research will allow an increase in the number of the samples in each postpartum interval in order to confirm these results.

Coenzyme Q10 supplementation during in vitro maturation of bovine oocytes (Bos taurus) helps to preserve oocyte integrity after vitrification

Oocyte vitrification causes less cell stress than slow cooling, but cytoskeletal and spindle alterations may occur affecting the oocyte competence. In vitro maturation (IVM) supplementation with different antioxidant molecules has been performed to attenuate this harmful stress. Coenzyme Q₁₀ (CoQ₁₀ ) supplementation has previously shown to have positive effects in bovine and mouse in vitro embryo development. The aim of this study was to evaluate the effects of CoQ₁₀ during bovine oocyte IVM and vitrification. Cumulus-oocyte complexes (COCs) (n = 311) were cultured under standard maturation conditions with 0 μM (control), 25 μM and 50 μM CoQ₁₀ supplementation. After 22 hr, a cohort of 170 oocytes both from the control and from CoQ₁₀ -supplemented groups were vitrified, warmed and returned to incubation until 24 hr of maturation, while the rest of the oocytes (n = 141) remained fresh. Then, oocyte survival was assessed morphologically by stereomicroscopy. Oocytes from all groups were then fixed and stained for assessing cortical granules (CG) migration and nuclear stage. High rates of oocyte MII progression and appropriate CG migration as a continuous layer beneath the plasma membrane were obtained both in control and in CoQ₁₀ groups. Results showed that although vitrification has great impact in survival of IVM bovine oocytes, 50 μM CoQ₁₀ supplementation significantly improved oocyte survival (p = .045) and reduced the premature CG exocytosis, helping to preserve the CG migration pattern (31.3% control vs. 54.5% in 50 μM CoQ₁₀ ; p = .039), attenuating the negative effects of vitrification.

40 Gene Expression Profiling of In Vitro-Produced Blastocysts Derived from In Vitro-Matured Bovine Oocytes Vitrified/Warmed in Media Supplemented with a Biopolymer Produced by an Antarctic Bacterium

Previous reports have demonstrated the beneficial effect of antifreeze glycoprotein supplementation during oocyte vitrification on preventing ice crystal formation and thus enhancing developmental competence after vitrification-warming. Pseudomonas sp. ID1, a bacterium isolated from marine sediment from Antarctica, produces an exopolysaccharide, M1 EPS, as a cold adaptation mechanism. Despite numerous studies on structural and morphological damages induced by cryopreservation in oocytes, few studies have focused on the impact of vitrification on the expression pattern of genes during early embryo development. In the present study, the expression patterns of 6 genes (BAX, BCL2-like 1, DNMT3A, UBE2A, SCLC2A3, and HDAC1) were investigated in Day 8 blastocysts resulting from in vitro-matured oocytes vitrified/warmed in media supplemented with various concentrations of M1 EPS. After 21 h of IVM, 1,062 oocytes were vitrified/warmed in media supplemented with 0, 0.001, 0.01, 0.1, and 1 mg mL−1 M1 EPS. At 24 h of IVM, oocytes were in vitro fertilized and in vitro cultured and the resulting blastocysts were harvested at Day 8 for RNA extraction and qPCR analysis. Fresh, non-vitrified oocytes were used as a control. Analysis of gene expression was performed through Kruskall-Wallis test and followed by Mann-Whitney test, and the level of significance was set at P ≤ 0.05. No significant differences were detected in relative mRNA abundance for SLC2A3, UBE2A, or HDAC-1 between blastocysts derived from vitrified oocytes, regardless of M1 EPS treatment. Expression of DNMT3A was significantly higher in embryos obtained from oocytes vitrified and warmed with 0.1 mg mL−1 M1 EPS compared with other treatment groups. However, no differences in DNMT3A expression were observed when the other vitrified groups were compared. The relative abundance of BAX transcript in embryos from oocytes vitrified in media supplemented with 0.1 mg mL−1 M1 EPS was higher than that in 0 or 0.001 mg mL−1 groups. Embryos from 0.01 and 0.1 mg mL−1 groups showed higher BCL2-like 1 mRNA abundance than those from the 0, 0.001, and 1 mg mL−1 groups. Whereas blastocysts from oocytes vitrified with 0.01 mg mL−1 M1 EPS exhibited the lowest BAX:BCL2-like 1 ratio, no significant differences in BAX:BCL2-like 1 ratio were observed between the other treatments. The significantly lower BAX:BCL2 ratio observed in blastocysts obtained from oocytes vitrified with 0.01 mg mL−1 M1 EPS could be indicative for a better embryo quality. Although optimizing the use of M1 EPS may benefit oocyte cryopreservation protocols, further research is required to clarify the exact mechanism through which it exerts its protective role. This study was supported by the Spanish Ministry of Science and Innovation (Project AGL2016-79802-P and grant CTQ2014-59632-R).

175 Testis-Specific Protein Y Encoded Copy Number Variation in In Vitro-Produced Bovine Early Embryos

Testis-specific protein Y (TSPY) is one of the genes located in the male-specific region of the Y chromosome involved in male reproduction, particularly in spermatogenesis. It has been shown to have different copy number (CN) in different species, in different individuals within a species and in the same family (i.e. among brothers from the same father). Previous studies from our laboratory in the bovine species showed that different TSPY CN was correlated with fertility, as bulls with higher CN showed higher fertility rate. In this study, we investigated development rate in in vitro-produced (IVP) bovine early embryos produced by sex-sorted semen (X and Y) from 3 bulls (1, 2, and 3) and TSPY copy number variation (CNV) in the male blastocysts. The IVP embryos by the 3 different types of semen (sub-divided: 1X, 1Y, 2X, 2Y, 3X, 3Y) and parthenotes (PART) for the negative control were assessed for developmental rates (shown in Table 1 below) and individually collected at each cell stage from zygote to blastocyst to extract DNA for TSPY CN analysis. The DNA from individual blastocysts was treated with a restriction enzyme for relative quantification of TSPY CN using digital droplet PCR (ddPCR) with SRY, known to have only one copy in bovine, as a reference gene. Developmental data showed that Y-carrying semen had higher rates both in cleavage and blastocyst compared with X-carrying semen from the same bull. Particularly, bull 3 (both 3X and 3Y) had the highest developmental rates compared with the other 2 types of bulls. TSPY was detected in male blastocyst, where both parthenotes and female embryos were negative. Relative CN of TSPY versus SRY from blastocysts produced from bulls 1, 2, and 3 averaged to 87.5, 55, and 20, respectively. Interestingly, the CN among brother blastocysts showed a variation of less than 7.5, where bull-to-bull variation was approximately from 20 to 60 copies. Our results show that TSPY CN in the embryo varies according to the sire and among brother blastocysts. Moreover, TSPY CNV among brother blastocysts allows us to speculate that individually different recombination events occurred in meiosis during spermatogenesis. Table 1.Embryo development rate by semen type This research was funded by the Canada Research Chair’s program, Natural Sciences and Engineering Research Council of Canada and the Ontario Veterinary College.

Decrease in bovine in vitro embryo production efficiency during winter season in a warm-summer Mediterranean climate

Retrospective analysis of monthly embryo production from December 2011 to May 2015 and its correlation with meteorological data in our geographic zone was made. We had observed that in certain time of the year, in vitro blastocyst production decreases. Accordingly, was examined the association between blastocyst production and climatological parameters. Cleavage rates correlate positively with blastocyst rates (p < .05). Significant differences in cleavage rates between autumn and summer (79.8%; 71.5%), and between winter and autumn (71.8%; 79.8%), were found. Blastocyst production had lower efficiency in June (9 ± 12%) and July (4.9 ± 5.7%), which coincides with winter season. In contrast, higher embryo production was obtained in February (22.2 ± 9.7%), March (22.9 ± 14%) and September (25.2 ± 6.6%), which coincides with autumn and spring season. Similarly, embryo production correlates with meteorological parameters: blastocyst production positively correlates with sunshine hours, maximum temperature and average temperature. Similarly, blastocyst production inversely correlates with total precipitation and days >1 mm precipitation (p < .05). There is a significant decrease in bovine in vitro embryo production efficiency during winter season in our warm-summer Mediterranean climate zone. It remains to be investigated the direct effect of environmental factors on oocyte quality and its impact on in vitro production efficiency.

45 SPINDLE CONFIGURATION AND DNA FRAGMENTATION OF VITRIFIED BOVINE OOCYTES AFTER IN VITRO MATURATION WITH L-CARNITINE AND/OR RESVERATROL

After cryopreservation, oocytes may suffer morphological and functional damage, due to the high cytoplasm lipid content and to the reactive oxygen species formation. The aim of this work was to evaluate the spindle configuration and the DNA fragmentation of vitrified/warmed oocytes after in vitro maturation (IVM) in a media supplemented with l-carnitine and/or resveratrol, a lipolytic and antioxidant agent, respectively. The IVM viable COC with at least 3 cumulus cell layers and homogenous cytoplasm were randomly distributed into 4 groups: (1) control: conventional IVM media with TCM-199, epidermal growth factor, and 10% FCS; (2) L-CAR: control media supplemented with 0.6 mg mL–1 of l-carnitine; (3) RES: control media supplemented with 1 μM mL–1 of resveratrol; and 4) L+R: control media supplemented with 0.6 mg mL–1 of l-carnitine and 1 μM mL–1 of resveratrol. After 22 h of IVM, half of the COC from each group were vitrified and warmed, using the cryotop methodology. After warming, the oocytes were allowed to recover in their respective media for 2 additional hours. After 24 h of IVM, oocytes from all treatments were completely denuded and fixed and stained using specific fluorescent probes. The microtubule/chromosome configuration and the DNA fragmentation were analysed by immunocytochemistry under a fluorescent microscope (A.40FL, Carl Zeiss, Oberkochen, Germany). All statistical analyses were conducted with IBM SPSS 19 (IBM; Chicago, IL, USA). ANOVA was performed to analyse differences in meiotic spindle configuration, and the Chi-squared test was used for DNA fragmentation. The significance level was 5%. Although vitrification may cause severe oocyte damage, IVM with l-carnitine alone or in association with resveratrol was able to reduce the percentage of abnormal spindle configurations (Table 1), whereas the addition of resveratrol alone or its association with l-carnitine reduced DNA fragmentation of IVM oocytes after a vitrification/warming process. These results indicate the IVM supplementation with RES and/or L-CAR could modify oocyte composition, increasing its cryotolerance. However further studies are required to confirm the beneficial effect of these molecular interactions. Table 1.Evaluation of spindle configuration (Experiment 1) and apoptotic cell status (Experiment 2) of fresh or vitrified/warmed oocytes matured with RES and/or L-CAR

229 SHORT-TERM EXPOSURE OF MATURE OOCYTES TO A NITRIC OXIDE DONOR FOR INDUCING OXIDATIVE STRESS RESISTANCE ON IN VITRO-PRODUCED BOVINE EMBRYOS

Recent studies have shown that short-term exposure of oocytes to stressors such as hydrostatic pressure, osmotic stress, and oxidative stress might induce stress tolerance in embryos. In this research we studied the effect of short-term exposure of bovine in vitro-matured cumulus-oocyte complexes (COC) with a nitric oxide donor (SNP) on IVF, embryo development, embryo quality, and relative gene expression related to cell redox state regulation. The COC were selected and matured in TCM 199 supplemented with 10% inactivated FBS, 6 mg mL–1 of LH, 6 mg mL–1 of FSH, 1 mg mL–1 of oestradiol, and 0.2 mmol of pyruvate and then incubated for 22 to 24 h at 38.5°C in 5% CO2 in a humidified atmosphere (n = 12). Before IVF, mature COC were incubated during 1 h with different concentration of sodium nitroprusside, SNP (control without SNP, 10–6 M, 10–5 M, and 10–4 M SNP) in maturation media at 38.5°C and 5% CO2 in a humidified atmosphere. For IVF procedure, oocytes of each treatment and sperm of one bull were co-incubated for 18 to 20 h at 38.5°C and 5% CO2. Presumptive zygotes were separately cultured until Day 7 under mineral oil at 38.5°C and 5% CO2, 5%O2, and 90% N2 in a humidified atmosphere. Embryo quality was analysed by staining with CDX2 antibody for trophectoderm cells and compared with total embryo cells stained with Hoechst 33342. Relative gene expression for each treatment were evaluated after RNA extraction and cDNA synthesis in Stratagene MX 3000P real-time equipment with Agilent qPCR software MX pro 4.1 version. Differences between experimental groups (n = 12) were measured using a one-way ANOVA test in the STATGRAPHICS plus 5.1 version software. P < 0.05 was considered statistically significant. Cleavage percentage at 72 h post-insemination was significantly different between the control and 10–4 M SNP group (82 ± 8.4% v. 77 ± 7.1%, respectively) and between 10–5 M and 10–4 M SNP group (84.9 ± 4.1% v. 77 ± 7.1%, respectively). Blastocyst percentage at 7 days of culture was significantly different between control and 10–4 M SNP group (34.1 ± 7.8% v. 26.2 ± 4.9%, respectively). Embryo development between control group and treatments was similar within early, expanded, and hatched blastocyst percentage. Embryo quality of expanded blastocyst was similar between control group and treatments (ICM: TE). No significant differences in gene expression after SNP exposure was observed (iNOS, eNOS, nNOS, PRDX5, HSP70, HSP90, HIF1A, BCL2A). Oocytes incubated with a high concentration of SNP showed lower cleavage and blastocyst rates, showing that this treatment was deleterious for in vitro embryo production in bovine. However, there were no significant differences on embryo quality assessed by ICM : TE ratio and/or in gene expression pattern of 7-day cultured expanded blastocysts.

46 SPINDLE CONFIGURATION OF IN VITRO-MATURED BOVINE OOCYTES EXPOSED TO SODIUM CHLORIDE OR SUCROSE PRIOR TO CRYOTOP VITRIFICATION

It has been previously described that a simple treatment with medium containing elevated NaCl or sucrose concentrations increases the cryotolerance and developmental competence of in vitro-matured porcine oocytes after vitrification and parthenogenetic activation (Lin et al. 2009 Reprod. Fertil. Dev. 21, 338–344). This work was designed to study whether the exposure to increased concentrations of NaCl or sucrose before vitrification improves cryotolerance of in vitro-matured bovine oocytes. In Experiment 1, in vitro-matured oocytes were exposed to different NaCl and sucrose concentrations (from 375 to 808 mOsm) for 1 h. In Experiment 2, and according to the results obtained in the first experiment, oocytes were exposed to 375 mOsm NaCl or sucrose solution, vitrified, and warmed. Nontreated oocytes were used as controls. In both experiments, oocytes were fixed after treatment and microtubule, and chromosome distribution was analysed by immunocitochemistry. All statistical analyses were conducted with the IBM SPSS 19 for Windows (IBM corp., Chicago, IL). ANOVA was performed to analyse differences in meiotic spindle. Statistical significance was set at P < 0.05. After exposure to 375 mOsm of NaCl or sucrose, similar percentages of oocytes showing normal chromosome distribution were obtained compared to the control group (83.4, 71.8, and 85.0%, respectively). Groups treated with higher concentrations (443 to 808 mOsm) triggered significantly lower proportions of normal spindles. After vitrification/warming, no significant differences were observed between nonvitrified oocytes (71.3%) and those treated with NaCl before vitrification/warming procedure (41.9%) when normal chromosome organisation was analysed. Significantly higher percentages of normal chromosome configuration were observed when oocytes were exposed to sucrose before vitrification (34.2%) compared with control-vitrified oocytes (23.3%). However, pretreatment with NaCl or sucrose before vitrification did not trigger significant differences in terms of percentages of normal microtubule configuration (41.9 and 32.9%, respectively) compared with control-vitrified oocytes (40.2 and 24.4%, respectively), although both treatments differed significantly from control (79.1 and 81.7%, respectively). In conclusion, this study showed that a 375-mOsm NaCl or sucrose pretreatment of bovine oocytes before vitrification did not have a deleterious effect on the organisation of the meiotic spindle of vitrified/warmed bovine oocytes. Further experiments are required to investigate whether in vitro-matured oocytes subjected to this osmotic treatment could improve their development competence after being vitrified/warmed.

70 ONE-STEP CRYOPROTECTANT DILUTION FOLLOWING VITRIFICATION OF IN VITRO-PRODUCED BOVINE EMBRYOS

Although slow freezing continues to be the most widely used technique of cryopreservation for bovine in vivo- and in vitro-produced embryos, vitrification has been tested in different species with good results, especially when dealing with in vitro-produced embryos. Vitrification represents a minor expense in time and equipment associated with cryopreservation compared with conventional slow freezing. However, vitrification, which is the most common method for human embryo cryopreservation, has not been widely adopted by embryo-transfer practitioners for commercial use in cattle. In general, vitrification requires gradual cryoprotectant dilution in a laboratory setting, and it is difficult to perform in the field. The objective of this study was to develop a one-step dilution method suitable for one-step bovine embryo transfer using the cryotop vitrification method. Embryos produced in vitro by standard procedures were vitrified at the blastocyst stage at Day 7 post-insemination in a mixture of 15% ethylene glycol + 15% dimethyl sulfoxide + 0.5 M sucrose using cryotop devices. Embryos were randomly assigned to 1 of 3 warming methods: (1) W3: warming was carried out following the cryotop method (1 M sucrose for 1 min, 0.5 M sucrose for 3 min, and 0 M sucrose for 6 min); (2) W1/0.5: embryos were warmed directly in 0.5 M sucrose for 3 min; and (3) W1/0: embryos were warmed directly in 0 M sucrose for 5 min. Survival rates were assessed in terms of blastocyst re-expansion, hatching, and hatched status at 3 and 24 h after warming. Data were analyzed using the statistical analysis systems package (SAS, v9.1). Data from at least 3 replicates were collected. Comparisons of vitrified–warmed blastocyst survival rates between groups were performed using the chi-squared test. The level of statistical significance was set at P < 0.05. When embryo survival was evaluated at 3 h postwarming, embryos warmed using the 3-step dilution protocol and those warmed directly in 0.5 M sucrose showed higher percentages of survival (W3: 89.8%, n = 98; W1/0.5: 87.5%, n = 64; P < 0.05) than those blastocysts that were warmed directly in 0 M sucrose (W1/0: 66.4%, n = 146). However, similar rates irrespective of the warming procedure were observed at 24 h postwarming (W3: 85.7%, W1/0.5: 88.2%, W1/0: 70.5%). Warmed in vitro-produced embryos exposed to W3 (47.6%) and W1/0.5 (35.6%) achieved higher percentages of embryos developing to the hatched blastocyst stage after 24 h of culture than those embryos warmed in W1/0 (20.4%; P < 0.05). Our results indicate that direct warming and dilution of cyotop-vitrified embryos in 0.5 M sucrose for 3 min may enable one-step bovine embryo transfer without requirement of a microscope or other laboratory equipment, simplifying the embryo-transfer procedure of vitrified embryos on farm at the same level of complexity as carrying out AI. Support came from Spanish MEC (RZ2010-00015-0-00; AGL2010-19069) and Generalitat de Catalunya (2009 SGR 621).

60 THE EFFECT OF L-ASCORBIC ACID DURING CULTURE, CRYOPRESERVATION, OR BOTH ON PORCINE EMBRYOS PRODUCED IN VITRO

The benefits of adding l-ascorbic acid during the cryopreservation procedure have been reported before in mouse and bovine. In this study, the effects of l-ascorbic acid (AC) supplementation during culture, cryopreservation, or both procedures on the developmental ability and embryo quality of in vitro produced porcine blastocysts were examined. Embryo quality criteria consisted of total cell number, percentage of apoptosis, and cryotolerance. After in vitro fertilisation, presumptive zygotes were randomly assigned to 2 culture treatments in which the culture medium NCSU23 was supplemented with 100 µM AC (n = 1162) or nonsupplemented (n = 1163) for a 144-h period. On Day 6, blastocyst formation was assessed by stereomicroscopy, and a representative fraction of Grade I- and II-blastocysts of each culture treatment was evaluated using 4′,6-diamidino-2-phenylindole-TUNEL co-staining and considered as fresh-control. The remaining fraction of Grade I- and II-blastocysts was vitrified/warmed following the Cryotop® method. To determine the effect of AC supplementation during cryopreservation procedures, each culture treatment was divided into 2 groups: (1) embryos exposed to 100 µM AC, and (2) nonexposed embryos (vitrified-control). Survival was determined according to reexpansion rates after 24 h of recovery in NCSU23 medium. After 24 h, reexpanded blastocysts were co-stained using the 4′,6-diamidino-2-phenylindole-TUNEL technique, and total number of cells and apoptosis indexes were determined. Experiment was replicated 9 times for each group. Data were analyzed by t-test for independent variables and a 2-way ANOVA. Results are expressed as means ± SE, and the significant level was set at 5% (Table 1). After culture, supplementing NCSU23 medium with AC showed no significant differences in blastocyst formation (fresh-control 11.6 ± 7.8 v. AC 11.6 ± 7.7), in number of cells (fresh-control 36.7 ± 15.8 v. AC 36.1 ± 15.9), or in apoptosis index (fresh-control 2.9 ± 5.7 v. AC 3.5 ± 4.7). On the other hand, only when both culture and vitrified media were supplemented with AC was there a significant increase of blastocyst survival. In contrast, no significant differences in embryo survival were observed when only 1 of these 2 media (culture or vitrification) was supplemented. Supplementing culture media or cryopreservation solutions with AC did not affect the total cell number or apoptosis index in vitrified blastocysts. In conclusion, the addition of 100 µM l-ascorbic acid to the culture and cryopreservation solutions improves the cryotolerance of in vitro-produced porcine blastocysts. Table 1.Survival of blastocysts (24 h), total cell number, and percentage of apoptosis after vitrification/warming

Cryotolerance of in vitro-produced porcine blastocysts is improved when using glucose instead of pyruvate and lactate during the first 2 days of embryo culture

The objective of the present study was to determine the effects of replacing glucose with pyruvate and lactate during the first 48 h of in vitro culture (IVC) in NCSU-23 medium on embryo development, embryo quality and survival of porcine blastocysts after vitrification. To this end, in vitro-produced (IVP) porcine oocytes were cultured with either glucose for 6 days (IVC-Glu) or pyruvate–lactate from Day 0 to Day 2 and then with glucose until Day 6 (IVC-PyrLac). Blastocysts were vitrified on Day 6 using the Cryotop device and, after warming, survival rate and the apoptosis index were evaluated after 24 h incubation in NCSU-23 medium. No significant differences were observed between IVC-Glu and IVC-PyrLac in terms of cleavage rate, blastocyst yield, total number of cells per blastocyst or the apoptosis index (1.82 ± 0.75% vs 3.18 ± 0.88%, respectively) of non-vitrified embryos. However, a significant increase was seen in hatching/hatched blastocysts in the IVC-PyrLac compared with IVC-Glu treatment group (12.71 ± 1.20% vs 3.54 ± 0.47%, respectively). Regardless of treatment, vitrification impaired the survival rate and the apoptosis index. When comparing both treatments after warming, the percentage of apoptotic cells was significantly higher for blastocysts in the IVC-PyrLac compared with IVC-Glu group (18.55 ± 3.49% vs 9.12 ± 2.17%, respectively). In conclusion, under the conditions of the present study, replacement of glucose with pyruvate–lactate during the first 48 h of culture resulted in a lower cryotolerance of IVP porcine embryos.

142 ZONA PELLUCIDA TAGGING WITH BARCODES ALLOWS THE TRACEABILITY OF BOVINE EMBRYOS CULTURED IN GROUP

The low number of oocytes collected from unstimulated donors by ovum pick-up means that embryos produced from each female have to be cultured in very small groups. Because embryo quality and development rates are reduced in individual and small group culture, several methods to culture embryos individually but sharing the same medium have been designed. However, these systems prevent embryo movements, interfering with paracrine factors transmission and gradient changes. Here, we present an alternative in vitro culture method to allow the co-culture of embryos from different origins, without movement restriction and preserving their pedigree, by labelling the zygotes with polysilicon barcodes attached to the outer surface of the zona pellucida (ZP). Barcodes (10 × 6 × 1 µm) with 8 rectangular bits of binary codification (256 possible combinations), which can be read under a standard inverted microscope, were fabricated using silicon microtechnologies. To provide the barcodes with a ZP-binding capacity, they were biofunctionalized by self-assembled monolayers with the wheat germ agglutinin (WGA) lectin, which recognizes specific saccharides highly abundant in the ZP of most mammalian species. As a proof of concept, the culture method was tested on bovine zygotes produced from slaughterhouse-derived cow oocytes matured and fertilized in vitro. Using a mouth-controlled pipette, presumptive zygotes were individually rolled over WGA-biofunctionalized barcodes (8 barcodes/embryo) previously placed at the bottom of a drop of manipulation media. Four different barcodes, each one with a different codification, were used to encode 25 embryos (6–7 embryos/barcode codification), which were then cultured together in the same drop of medium. Day 7 (D7) and Day 8 (D8) blastocyst, and barcode retention rates were assessed. In addition, D7 expanded blastocysts were vitrified by the cryotop method and post-warming survival was determined as re-expansion rate at 24 h in culture. Finally, the quality of D8 blastocysts was assessed by differential staining and counting of inner cell mass (ICM) and trophectoderm (TE) cells. In all the experiments, a control group without barcodes was cultured and vitrified-warmed. Data were analyzed by chi-square and Mann–Whitney tests. The presence of barcodes attached to the ZP did not affect in vitro embryo development (D8 blastocysts: 29.7% control n = 309, 36.2% encoded n = 315), post-warming survival (86.4% control n = 66, 80.5% encoded n = 82), or blastocyst quality (IMC/TE: 22.1 ± 1.4/64.5 ± 5.7 control n = 18, 22.2 ± 1.7/64.1 ± 6.1 encoded n = 23). The labelling system was effective until D8 of culture, as all the embryos maintained barcodes attached (4 ± 1.8 barcodes/embryo) and could be identified, even after undergoing vitrification and warming. In conclusion, identification of co-cultured embryos by biofunctionalized barcodes attached to the ZP is feasible and will allow to culture embryos from different donors in the same drop, keeping the benefits of collective culture. Support was provided by Spanish MEC (TEC2011-29140-C03; RZ2010-00015-0-00; AGL2010-19069), Generalitat Catalunya (2009 SGR 282 and 621), and PIF-UAB Fellowship.

Developmental competence and embryo quality of small oocytes from pre-pubertal goats cultured in IVM medium supplemented with low level of hormones, insulin-transferrin-selenium and ascorbic acid

The aim of this study was to test the effect of insulin-transferrin-selenium (ITS) and L-ascorbic acid (AA) supplementation and the hormonal level during in vitro maturation (IVM) of small oocytes from pre-pubertal goat on the blastocyst yield and quality. Concretely, we used four maturation media: conventional IVM medium (CM), growth medium (GM: CM+ITS+AA and low level of hormones), modified CM (mCM: CM with low level of hormones) and modified GM (mGM: CM+ITS+AA and normal level of hormones). Cumulus-oocyte complexes (COCs) were classified into two categories according to oocyte diameter: <125 μm and ≥ 125 μm. Large oocytes were matured 24 h in CM (Treatment A). Small oocytes were matured randomly in six experimental groups: Treatment B: 24 h in CM; Treatment C: 12 h in GM and 12 h in CM; Treatment D: 24 h in mGM; Treatment E: 12 h in mGM and 12 h in CM; Treatment F: 12 h in mCM and 12 h in CM; and Treatment G: 12 h in GM and 12 h in mGM. After IVM, oocytes were fertilized and cultured for 8 days. The blastocyst quality was assessed by the survival following vitrification/warming and the mean cell number. When different maturation media were combined, the blastocyst rate did not improve. The large oocytes produced the highest blastocysts yield. However, the culture of small oocytes in GM (53.3%) enhanced the post-warming survival of blastocysts compared to large oocytes matured in CM (35.7%). In conclusion, IVM of pre-pubertal goat small oocytes in GM would be useful to improve the quality of in vitro-produced blastocysts.

260 IN VITRO DEVELOPMENTAL COMPETENCE OF PREPUBERTAL GOAT OOCYTES CULTURED IN GROWTH MEDIUM

The prepubertal goat ovary presents a large number of small oocytes with a compromised competence to develop up to blastocyst stage. In pigs (Wu et al. 2006), using growth medium (GM) composed by low hormone concentrations, ascorbic acid, and insulin transferrin selenium (ITS) during the first 24 h of in vitro maturation (IVM) improved embryo development of small oocytes. The aim of this study was to test the GM in small prepubertal goat oocytes in order to increase blastocyst yield. The cumulus–oocyte complexes (COC) were recovered from prepubertal (1–2 months old) goat ovaries by slicing. The COC with a compact cumulus and homogeneous cytoplasm were selected and classified into 2 categories based on oocyte diameter: <125 μm and ≥125 μm. The ≥125 μm oocytes were matured in groups of 25 to 30 COC/100 μL drops of conventional IVM medium covered with mineral oil for 24 h (Treatment A). This medium was TCM-199 supplemented with 10% donor bovine serum, 10 μg mL–1 FSH, 10 μg mL–1 LH, 1 μg mL–1 17β-oestradiol, and 100 μM cysteamine. The <125 μm oocytes were distributed into 3 experimental groups: Treatment B, COC matured in the conventional IVM medium; Treatment C, COC cultured in GM (TCM-199, 10% donor bovine serum, 0.04 μg mL–1 FSH, 0.04 μg mL–1 LH, 0.004 μg mL–1 17β-oestradiol, 100 μM cysteamine, 100 μg mL–1 ascorbic acid, and 5 μL mL–1 ITS) for 12 h before placement for other 12 h in the conventional IVM medium, all drops of growth or maturation medium were covered with mineral oil; Treatment D, COC cultured during the first 12 h in GM and other 12 h into the conventional medium supplemented with 100 μg mL–1 ascorbic acid and 5 μL mL–1 ITS. After IVM, oocytes were fertilized for 24 h with a sperm concentration of 4 × 106 spz mL–1. Presumptive zygotes were cultured in SOF for 9 days. The cleavage rate was evaluated at 48 h post-insemination and blastocyst percentages at the final in vitro embryo culture (treatments A, B, C: 5 replicates; treatment D: 4 replicates). The results are shown in the Table 1. Cleavage and embryo development did not show different results when we compared small oocytes matured in GM to those matured in conventional IVM medium. However, the biggest oocytes (≥125 μm) showed the highest percentage of blastocyst development. The current study shows that the culture of small prepubertal goat oocytes in GM does not improve blastocyst yield. Table 1.Effect of growth medium on embryo development of small oocytes (<125 μm) from prepubertal goats

257 DETECTION OF MICROTUBULES BY POLARIZED LIGHT MICROSCOPY IN SHEEP AND GOAT OOCYTES

The meiotic spindle in the oocyte is composed of microtubules and plays a key role in normal chromosome alignment and segregation during meiosis. In oocytes from farm animals, the meiotic spindle cannot be detected by conventional light microscopy due to the characteristic of their cytoplasm. Conventional methods to image the meiotic spindle rely on fixation of the oocytes. Polarized light microscopy (PLM) allows noninvasive evaluation of the meiotic spindle of metaphase oocytes. The aim of this study was to assess the efficiency of polarized light microscopy to detect microtubule-polymerized protein within in vitro matured prepubertal sheep and goat oocytes. We carried out 2 studies. In the first one, cumulus–oocyte complexes from slaughterhouse sheep ovaries were matured in vitro for 27 h. After in vitro maturation, oocytes (n = 77) were denuded of cumulus cells and placed individually in 10-μL drops of TCM-199-HEPES-BSA in a glass Petri dish. Polarized light microscopy was used to detect the presence of polymerized protein, which could be associated with the forming of a meiotic spindle. To confirm the presence of the polymerized protein and the meiotic spindle, each individual oocyte was subjected to immunostaining and chromatin detection as described by (Morató et al. 2008 Mol. Reprod. Dev. 75, 191–201). The experiment was replicated 4 times. The correlation analysis was performed using the Proc Corr procedure of SAS. There was a positive correlation (r = 0.87; P < 0.001) between the signal obtained by PLM and the presence of microtubule-polymerized protein as confirmed by immunostaining. A positive PLM signal was detected in 87.0% of the oocytes, and 69.0% of the oocytes reached the metaphase II (MII) stage after in vitro maturation. A barrel-shaped spindle was observed in 77.3% of the MII oocytes. In the second study, we performed a similar experiment but used goat oocytes. A total of 78 oocytes were used, and PLM and immunostaining were performed in each individual oocyte as it was described with sheep oocytes. There was also a positive correlation (r = 1; P < 0.001) between the signal obtained by PLM and the presence of microtubule-polymerized protein. A positive PLM signal was detected in 98.7% of the oocytes, and 80.7% of the oocytes reached the MII stage after in vitro maturation. A barrel-shaped spindle was observed in 92.0% of the MII oocytes. These results indicate that PLM is an efficient system to detect polymerized protein in in vitro matured sheep and goat oocytes. This work was supported by the following grant: INIA: RZ2007-00013-00-00. M. Muñoz and D. Martín are sponsored by RYC08-03454 and PTA2007-0268-I, respectively.

A transcriptional signature associated with the onset of benign prostate hyperplasia in a canine model

BACKGROUND

Benign prostatic hyperplasia (BPH) represents the most frequent proliferative abnormality of the human prostate. In spite of the well-characterized architectural development of BPH, little is known about the cellular and molecular events that contribute to it.

METHODS

We have developed an animal model to evaluate the follow-up of hormone-induced BPH and the analysis of the gene expression associated with BPH. Immunohistochemistry on human patient samples validated the BPH-related molecular alterations.

RESULTS

Canine specific Affymetrix microarray analysis performed on sequential biopsies obtained from a beagle dog dynamic model characterized a number of genes altered during the onset of BPH. In addition to the genes involved in calcification, matrix remodeling, detoxification, cell movement, and mucosa protection (MGP, MMP2, TIMP2, ITIH3, GST, MT2A, SULT1A1, FKBP1B, MUC1, STRBP, TFF3), the up-regulation of TGFB3 and CLU indicated a complete adjustment of the transdifferentiation, senescence and apoptosis programs. The up-regulation of Clusterin was validated by RT-qPCR and immunohistochemistry, both in the dog dynamic model and in human samples, further confirming the suitability of the animal model for the study of the molecular alterations associated with BPH.

CONCLUSIONS

Transcriptome analysis performed on a dynamic animal model that accurately mimicked the human clinic, allowed us to characterize a gene expression pattern associated with the onset of BPH.

Oocyte secreted factors improve embryo developmental competence of COCs from small follicles in prepubertal goats

Oocytes secrete soluble paracrine factors called Oocyte Secreted Factors (OSFs) which regulate the cumulus cell phenotype. Follicle populations in ovaries from prepubertal females have smaller diameters than their adult counterparts. Oocytes from small follicles are less competent than those from large follicles. The aim of this study was to investigate, in prepubertal goats, the effect of OSFs secreted by denuded oocytes (DOs) from small (<3 mm) or large (>or=3 mm) follicles during IVM on embryo development and the blastocyst quality of cumulus-oocyte complexes (COCs) from small follicles and to determine if GDF9 participates in this process. Treatment groups were: (A) COCs non selected by their follicle size (control group); (B) cumulus oocytes complexes from small follicles (SFCOCs), (C) cumulus oocytes complexes from small follicles co-cultured with denuded oocytes from small follicles (SFCOCs + SFDOs), and (D) cumulus oocytes complexes from small follicles co-cultured with denuded oocytes from large follicles (SFCOCs + LFDOs). The effect of the addition of kinase inhibitor SB-431542, which antagonizes GDF9, was tested in A, C, and D treatment groups. Co-cultured SFCOCs with SFDOs or LFDOs significantly augmented the blastocyst rate in comparison to SFCOCs alone (15.77%, 17.39% vs. 10.31%, respectively). Blastocysts from SFCOCs + LFDOs group showed higher rates of tetraploid nuclei than blastocysts from SFCOCs and the control group (14.43% vs. 5.45% and 5.24%, respectively; P < 0.05). However, we did not observe differences in the hatching rate, mean cell number or embryo cryotolerance (P > 0.05) between the four treatment groups. The addition of SB-431542 during IVM did not have any effect on blastocyst rate (P > 0.05). In conclusion, in prepubertal goats, COCs with a low embryo developmental competence as a consequence of follicle size can be improved by coculturing them with denuded oocytes from both small and large follicles. GDF9 does not seem play a role in this improvement.

104 SURVIVAL AND APOPTOSIS RATES AFTER VITRIFICATION OF EARLY, EXPANDED, AND HATCHED CALF AND COW BLASTOCYSTS IN VITRO-PRODUCED USING CRYOTOP AS A DEVICE

Two experiments were designed to determine the ability of 7 and 8 day in vitro-produced blastocysts to survive to the vitrification procedure. Embryos were classified as early blastocysts, expanded, or hatching/hatched blastocysts. Vitrification was done using cryotop devices as described Du et al. (2007). After warming, blastocysts were incubated for 3 h in SOF medium. In the first experiment, we examined the developmental competence of early blastocysts, expanded blastocysts, and hatching/hatched blastocysts after vitrification using the Cryotop method. In the second experiment, warmed blastocysts that had been vitrified on cryotops were fixed in 4% formaldehyde and incubated with TUNEL staining for detecting DNA damaged nuclei. The percentage of TUNEL positive and negative blastomeres was assessed by confocal microscopy. In all experiments cow and calf blastocysts were compared. When the results according to the developmental stage were analyzed, no differences in the survival rates after vitrification of expanded and hatched blastocysts were observed at Day 8 from cow and calf blastocysts. After warming, survival rates of 52.4 and 50% were noted in the groups of expanded and hatched blastocysts respectively from Day 8 cow blastocysts. Similar results were observed in the groups of expanded (54.5%) and hatched (59.4%) blastocysts from Day 8 calf blastocysts. When embryos were vitrified at Day 7, survival rates of 78.4 and 66.7% were observed after warming expanded and hatched blastocysts from cows. In calves, a significant increase in the survival up to 83.3 and 80% was observed after warming expanded and hatched blastocysts. The lowest survival rates were observed in early blastocysts (from 26 to 51%), particularly in those vitrified at Day 8 (≤40%). Following vitrification, cell death was monitored in blastocysts 3 h after warming by TUNEL labelling of cells with damaged DNA. The TUNEL staining procedure was undertaken on Day 7 calf (n = 23) and cow (n = 25) blastocysts, as well as on Day 8 calf (n = 22) and cow (n = 30) blastocysts. When taking into account the stage of blastocyst development, there was a trend toward higher DNA integrity index after warming of expanded and hatched blastocysts compared with early blastocysts in calf and cow groups. So, cell damage was minimal in those blastocysts vitrified at expanded and hatched stage and rates were comparable with those from control fresh blastocysts. These findings suggest that the Cryotop technique seems to be particularly useful for blastocysts presenting a high degree of expansion (expanded and hatched blastocysts), mainly those blastocysts vitrified and warmed at Day 7.

Ability of Catalonian donkey sperm to penetrate zona pellucida-free bovine oocytes matured in vitro

An experiment was designed to study the interaction between fresh/frozen-thawed donkey spermatozoa and zona pellucida (ZP)-free bovine oocytes in an attempt to develop a model for assessing cryopreserved Catalonian donkey sperm function. Semen from five donkeys was collected using an artificial vagina. Sperm motility and viability were immediately assessed and the semen sample cryopreserved. Sperm viability and motility were then reassessed immediately after thawing. The motion characteristics of the fresh and frozen-thawed spermatozoa were determined using a computer-assisted sperm analysis system. In vitro-matured cow oocytes were inseminated with different percent live donkey sperm (high (>60%) or low (<40%) viability donkey sperm). After 18h of co-incubation, the oocytes were fixed, stained with 4',6-diamidino-2-phenylindole (DAPI) and examined for sperm penetration, the number of penetrated spermatozoa per oocyte, and male pronucleus formation. Frozen-thawed spermatozoa from high viability semen showed significantly lower VCL, VAP and mean ALH values than did high viability fresh spermatozoa. In contrast, frozen-thawed spermatozoa of low viability had significantly higher velocity values than fresh spermatozoa of low viability. A significant positive correlation (P<0.01) was detected between percentage fertilization and viability (r=0.84), and between percentage fertilization and certain CASA parameters (VAP, r=0.56; VCL, r=0.61 and mean ALH, r=0.68). Fresh or frozen-thawed high viability spermatozoa penetrated 90.1% and 85.4% of bovine oocytes respectively. Lower rates of penetration were observed for fresh and frozen-thawed low viability spermatozoa (34% and 22.5% respectively). The donkey spermatozoa were able to fuse with the oolema and even to decondense and form the male pronucleus (85-94%). Larger numbers of penetrated spermatozoa per oocyte were recorded when high viability sperm samples were used, whether fresh (3.02 vs. 1.12 for low viability sperm) or frozen-thawed (3.41 vs. 1.47). Consequently, low viability sperm samples showed higher percentages of monospermic penetration (91.17% and 61.97% for fresh and frozen-thawed sperm samples respectively). These findings suggest that bovine oocytes provide a useful model for assessing the penetration potential of frozen-thawed donkey sperm.

242 DETECTION OF MICROTUBULES BY POLARIZED LIGHT MICROSCOPY IN BOVINE OOCYTES

Polarized light microscopy (PLM) is being used as a tool in assisted reproductive technologies in humans and, more recently, in farm animals. Polarized light microscopy may allow for a quick localization or removal of nuclear structures, or both in the oocyte without fluorochrome staining and ultraviolet exposure, and may reduce nuclear damage when performing intra-cytoplasmic sperm injection. The aim of this study was to assess the efficiency of PLM to detect microtubule-polymerized protein within in vitro-matured bovine oocytes. Cumulus–oocyte complexes from slaughterhouse ovaries were matured in vitro for 23 h in bicarbonate-buffered TCM-199, FSHp (1 μg mL–1), LH (5 μg mL–1), 17β-estradiol (1 μg mL–1), and 10% fetal calf serum at 38.7°C in 5% CO2 in air with high humidity. After in vitro maturation, oocytes (n = 98) were denuded with 0.5% hyaluronidase and were placed individually in 10-μL drops of TCM-199-HEPES-BSA in a glass Petri dish. Polarized light microscopy was used to detect the presence of polymerized protein that could be forming a meiotic spindle. To confirm the presence of the polymerized protein and the meiotic spindle, each individual oocyte was subjected to immunostaining and chromatin detection as described by Morató et al. 2008 Mol. Reprod. Dev. 75, 191–201. The experiment was replicated 6 times. There was an absolute positive correlation (r = 1; P < 0.0001) between the signal obtained by PLM and the presence of microtubule-polymerized protein as confirmed by immunostaining. A barrel-shaped spindle was observed in 40% of the individual samples, whereas disorganized microtubule structures were obtained in 55% of the samples. The biological implication of these findings needs to be explored. However, PLM seems to be an efficient system to detect polymerized protein in in vitro-matured bovine oocytes.

Effect of ICSI and embryo biopsy on embryo development and apoptosis according to oocyte diameter in prepubertal goats

ICSI and embryo biopsy are routine methods used for assisted reproduction. However, their impact on embryo quality is still poor studied. Moreover, oocyte size is also a crucial factor for blastocyst production. In this study effect of oocyte size, ICSI and embryo biopsy was assessed in terms of incidence of apoptosis and blastocyst development. IVM-oocytes from prepubertal goats were fertilized by ICSI or IVF. Embryos obtained were divided depending on oocyte size, biopsied at day-4 post-insemination/injection and cultured for additional 4-5 days. Apoptotic cell number was assessed by TUNEL staining in day-4 embryos and blastocysts obtained. In each diameter group, ICSI did not affect embryo development, blastocyst cell number and embryo apoptotic grade in comparison to IVF. Embryo biopsy did not affect blastocyst rate and apoptotic cell number, but decreased blastocyst cell number (P=0.0018). Moreover, there was a negative relationship between blastocyst cell number and apoptotic grade (P<0.05). In conclusion, ICSI and embryo biopsy do not have negative effect on embryo quality and development. However, oocyte size has a positive relationship on blastocyst yield and quality.

200 EFFECT OF OOCYTE SIZE AND MICROMANIPULATION TECHNIQUES (ICSI AND EMBRYO BIOPSY) ON GOAT EMBRYO QUALITY

The aim of this study was to evaluate embryo quality of prepubertal goat oocytes after micromanipulation techniques: ICSI and embryo biopsy. Prepubertal goat oocytes were recovered from a slaughterhouse and matured in IVM medium (TCM-199 with serum, hormones, and cystamine) for 27 h. Spermatozoa were selected by swim-up and capacitated with heparin (10 µg mL−1) plus ionomycin (200 nM) for 15 min. A total of 930 IVM oocytes were divided into 4 groups depending on size (Group I: 110–125 µm, and Group II: &gt;125 µm) and fertilization procedure: ICSI or IVF. Zygotes were cultured in TALP fertilization medium. At 24 h post-insemination (hpi), zygotes were cultured in SOF. At 48 hpi, oocyte cleavage was recorded. Four days after insemination, a sample of 8-cell embryos was biopsied by removal of one blastomere. After biopsy, embryos were cultured in SOF for a further 4 days. Blastocysts were stained by TUNEL to assess apoptotic cell percentage. Results are shown in Table 1. Biopsied and non-biopsied embryos from Group II had higher blastocyst rates than those in Group I both in ICSI and IVF (P ≤ 0.02). Group II had also larger blastocyst cell numbers than Group I both in ICSI and in IVF (P ≤ 0.001). Moreover, blastocysts from Group II non-biopsied embryos had statistically larger cell numbers than those from the biopsied ones (P ≤ 0.05). Blastocysts from Group II had a lower apoptotic rate than those in Group I both in ICSI and IVF (P ≤ 0.05). In conclusion, oocytes larger than 125 µm were more competent to achieve embryo development than smaller oocytes. ICSI did not reduce embryo quality, either in blastocyst cell number or apoptotic index, when compared with IVF. Furthermore, embryo biopsy did not reduce blastocyst rates or apoptotic index. However, embryo biopsy reduced blastocyst cell number in Group II-derived blastocysts. Table 1.Effect of oocyte size and micromanipulation techniques on goat embryo quality

338 INFLUENCE OF OOCYTE DIAMETER AND MORPHOLOGY ON APOPTOSIS AND BLASTOCYST DEVELOPMENT IN PREPUBERTAL GOAT

In vitro embryo production from prepubertal females is lower than from adult females. There are different hypotheses to explain this fact. The aim of this study was to analyze the apoptosis of prepubertal goat oocytes and its relationship to embryo development according to oocyte diameters. Oocytes from slaughtered prepubertal goats were recovered by slicing, and classified as: healthy (H: compact cumulus cells and homogeneous cytoplasm) and early atresic (EA: granulated cytoplasm and/or initial cumulus expansion), and by oocyte diameter: 110–125 µm, 125–135 µm, and &gt;135 µm. They were matured in TCM-199 for 27 h at 38.5°C and 5% CO2 in air. After maturation, a sample of oocytes was denuded, and oocytes and cumulus cells, separately, were analyzed by TUNEL assay (In Situ Cell Death Detection Kit; Roche Diagnostics SL, Barcelona, Spain) to study the apoptosis. The rest of oocytes were fertilized in vitro and the presumptive zygotes were cultured for 8 days in SOF at 38.5°C, 5% CO2 and 90% N2. Results are shown in Table 1. Fisher's exact test showed a significantly higher percentage of blastocyst formation in the largest oocytes than in those with smaller diameters; moreover, the largest healthy oocytes produced a higher rate of blastocyst formation than the early atretic oocytes of the same diameter group. TUNEL assay showed that the percentage of apoptotic oocytes was lower in the largest healthy oocytes, whereas in early atresic oocytes, apoptosis was not related to oocyte size. After maturation, the percentage of apoptotic cumulus cells was low (10% of cells) in all oocyte categories. However, in the early atretic group, the percentage of apoptotic cumulus cells increased in oocytes &lt; 125 µm. In conclusion, in prepubertal goat oocytes, the percentage of blastocysts formed depends on oocyte diameter and the percentage of apoptotic cumulus cells. Table 1.Effect of oocyte diameter and morphology on apoptosis and blastocyst development This work was supported by a grant from Generalitat de Catalunya (2006FIC 00187) and a grant from the Universitat Autonoma de Barcelona (EME-2004-25).

124 TAXOL™ COULD PROMOTE EMBRYO DEVELOPMENT OF BOVINE OOCYTES VITRIFIED BY OPS

Stabilizing the cytoskeleton system during vitrification could be beneficial for improving post-thawed survival and subsequent development of vitrified oocytes. Taxol™, paclitaxel, is a microtubule stabilizer that has been found to improve development competence of vitrified mouse and human oocytes. The objective of this work was to study the effect of a Taxol pretreatment before OPS vitrification on the post-thaw cow and calf oocyte development. Oocytes were aspirated from slaughterhouse-derived ovaries and matured in TCM-199. Oocytes were randomly assigned to one of 3 experimental groups: (1) control oocytes matured in vitro for 24 h, (2) oocytes matured for 22 h and vitrified by the OPS method (Vajta et al. 1998 Mol. Reprod. Dev. 51, 53–58), and (3) oocytes matured for 22 h and vitrified by OPS method with 1 µM Taxol. OPS and Taxol–OPS oocytes were transferred back into the maturation dishes and matured for 2 additional h before being subjected to fertilization. Fertilization was performed using frozen–thawed Percoll-selected sperm. At 22 h after insemination, presumptive zygotes were pipetted and then cultured in drops of 25 µL SOF medium and 5% fetal calf serum under paraffin oil at 38.5°C in 5% CO2, 5% O2, 90% N2, and maximum humidity. The Taxol–OPS group provided a significantly higher cleavage rate than the OPS group in cows (41.9% and 34.0%, respectively) or in calves (33.7% and 23.5%, respectively). However, cleavage rate in the experimental groups was significantly lower than in the control group (78.3% and 69.7% for cow and calf control groups, respectively). Blastocyst yield was also higher for the Taxol–OPS group (3.2%) than the OPS group (0%) in cow oocytes. There was no blastocyst development when calf oocytes were vitrified with or without Taxol pretreatment. As expected, cow and calf vitrification groups triggered a significantly lower blastocyst yield when compared with their control (26.7% and 14.9% for cow and calf control groups, respectively). In conclusion, this study showed that supplementation of 1 µM Taxol could promote embryo development after thawing. Further research is indicated to clarify the function of Taxol and its optimal concentration in order to improve the rate of embryo development. Table 1. Effect of Taxol pretreatment on development of cow and calf oocytes vitrified by OPS

Expression of androgen, oestrogen alpha and beta, and progesterone receptors in the canine prostate: differences between normal, inflamed, hyperplastic and neoplastic glands

The expression of receptor for androgen (AR), oestrogen alpha and beta (ERalpha and ERbeta) and progesterone (PR) was examined immunohistochemically in canine prostate specimens (normal, hyperplastic, inflamed [prostatitis] or neoplastic). AR immunolabelling was seen in 100% of epithelial cells of normal and hyperplastic tissue, the corresponding figures for inflamed and carcinomatous tissue being 74% and 65%, respectively. ERalpha labelling was seen in 85% of epithelial cells in normal prostate glands, the corresponding figures for hyperplastic, inflamed and neoplastic glands being 35%, 22% and 12%, respectively. ERbeta labelling was seen in 85% of epithelial cells of normal glands and in about 70% of such cells in glands showing pathological changes. On the other hand, PR expression (weak) in normal glands was observed in fewer epithelial cells (44%) than in hyperplastic (70%), inflamed (62%) or neoplastic (64%) glands.

Gluconeogenesis-Linked Glycogen Metabolism Is Important in the Achievement of In Vitro Capacitation of Dog Spermatozoa in a Medium Without Glucose1

In vitro capacitation of dog spermatozoa in a medium without sugars and with lactate as the metabolic substrate (l-CCM) was accompanied by a progressive increase of intracellular glycogen during the first 2 h of incubation, which was followed by a subsequent decrease of glycogen levels after up to 4 h of incubation. Lactate from the medium is the source for the observed glycogen synthesis, as the presence of [(14)C]glycogen after the addition to l-CCM with [(14)C]lactate was demonstrated. The existence of functional gluconeogenesis in dog sperm was also sustained by the presence of key enzymes of this metabolic pathway, such as fructose 1,6-bisphophatase and aldolase B. On the other hand, glycogen metabolism from gluconeogenic sources was important in the maintenance of a correct in vitro fertilization after incubation in the l-CCM. This was demonstrated after the addition of phenylacetic acid (PAA) to l-CCM. In the presence of PAA, in vitro capacitation of dog spermatozoa suffered alterations, which translated into changes in capacitation functional markers, like the increase in the percentage of altered acrosomes, a distinct motion pattern, decrease or even disappearance of capacitation-induced tyrosine phosphorylation, and increased heterogeneity of the chlorotetracycline pattern in capacitated cells. Thus, this is the first report indicating the existence of a functional glyconeogenesis in mammalian spermatozoa. Moreover, gluconeogenesis-linked glycogen metabolism seems to be of importance in the maintenance of a correct in vitro capacitation in dog sperm in the absence of hexoses in the medium.

In vitro Capacitation and Acrosome Reaction of Dog Spermatozoa can be Feasibly Attained in a Defined Medium Without Glucose

Incubation of dog spermatozoa in a medium without glucose and in the presence of lactate and pyruvate (l-CCM) for 4 h at 38.5 degrees C in a 5% CO(2) atmosphere induced in vitro capacitation of these cells. This was verified after the combined specific capacitation-like changes in percentages of viability and altered acrosomes, motility characteristics, sperm location of reactivity against Pisum sativum, Arachis hypogaea and Helix pomatia lectins and the tyrosine phosphorylation pattern. Furthermore, a feasible acrosome reaction (AR) was induced when spermatozoa incubated in l-CCM for 4 h were further co-incubated for 1 h with canine oocytes. This was demonstrated by AR-like changes in percentages of viability, altered acrosomes, motility characteristics and sperm location of reactivity against P. sativum, A. hypogaea and H. pomatia lectins. All these results clearly indicate that in vitro capacitation, and subsequent AR, can be feasibly achieved without the presence of sugars. This ability can be related to the specific characteristics of energy-metabolism regulation reported in dog spermatozoa.

Differential effects of glucose and fructose on hexose metabolism in dog spermatozoa

Incubation of dog spermatozoa with 10 mmol l(-1) glucose or fructose rapidly increased the intracellular content of glucose 6-phosphate and fructose 6-phosphate, although the effect of fructose was greater. These effects were correlated with increases in ATP, ribose 5-phosphate and glycogen contents, and in the rates of formation of L-lactate and CO2. In all cases, except for ATP and glycogen, the effect of fructose was greater than that of glucose. The total hexokinase activity of the crude extracts of dog spermatozoa was more sensitive to fructose than to glucose at lower concentrations (0.1-3.0 mmol l(-1)). Both monosaccharides induced a fast and intense increase in the overall tyrosine phosphorylation of dog spermatozoa, although their specific induced-phosphorylation patterns differed slightly. Glut 3 and Glut 5 hexose transporters were the main hexose transporters in dog spermatozoa; however, other possible SGLT family-related hexose transporters were also localized. These data indicate that, at concentrations from 1 mmol l(-1) to 10 mmol l(-1), fructose has a stronger effect than glucose on hexose metabolism of dog spermatozoa. These differences appear to be related to variations in the sensitivity of hexokinase activity. Moreover, the differential hexose metabolism induced by the two sugars had distinct effects on the function of dog spermatozoa, as revealed by the diverse patterns of tyrosine phosphorylation.

Differential effects of glucose and fructose on hexose metabolism in dog spermatozoa

Incubation of dog spermatozoa with 10 mmol l(-1) glucose or fructose rapidly increased the intracellular content of glucose 6-phosphate and fructose 6-phosphate, although the effect of fructose was greater. These effects were correlated with increases in ATP, ribose 5-phosphate and glycogen contents, and in the rates of formation of L-lactate and CO2. In all cases, except for ATP and glycogen, the effect of fructose was greater than that of glucose. The total hexokinase activity of the crude extracts of dog spermatozoa was more sensitive to fructose than to glucose at lower concentrations (0.1-3.0 mmol l(-1)). Both monosaccharides induced a fast and intense increase in the overall tyrosine phosphorylation of dog spermatozoa, although their specific induced-phosphorylation patterns differed slightly. Glut 3 and Glut 5 hexose transporters were the main hexose transporters in dog spermatozoa; however, other possible SGLT family-related hexose transporters were also localized. These data indicate that, at concentrations from 1 mmol l(-1) to 10 mmol l(-1), fructose has a stronger effect than glucose on hexose metabolism of dog spermatozoa. These differences appear to be related to variations in the sensitivity of hexokinase activity. Moreover, the differential hexose metabolism induced by the two sugars had distinct effects on the function of dog spermatozoa, as revealed by the diverse patterns of tyrosine phosphorylation.

Effects of glucose and fructose on motility patterns of dog spermatozoa from fresh ejaculates

This study was performed to gain insight about how fructose and glucose modulate dog spermatozoa motility in the absence of other motility-modulating factors. Incubation of dog spermatozoa from fresh ejaculates in a basal medium without sugars for 60 min at 37 degrees C induced a progressive decrease in the percentage of motile spermatozoa and in some mean motility parameters, such as mean velocity (VAP), linear coefficient (LIN) and dance (DNC), and an increase in the mean frequency of head displacement (BCF). This indicates a progressive loss of linearity and an increase in oscillatory movement. Addition of 10 mM fructose prevented these effects. Incubation in a basal medium with 10 mM glucose for 60 min at 37 degrees C provoked a fast and intense decrease of LIN and a slight increase of DNC, inducing a less linear and more oscillatory mean movement. Neither fructose nor glucose modified the percentage of motile spermatozoa. The response to both sugars was dose-dependent, with differences appearing at concentrations as low as 1 mM. An analysis of the spermatozoa subpopulation placed above the 95th percentile of the whole population and a factorial analysis of the data indicated that the changes in the mean values of the motility parameters were mainly due to a specific motile subpopulation that had a strong reaction to the two sugars. Our results indicate that fructose, at concentrations from 1 to 10 mM, induced a more linear and less oscillatory motility pattern than glucose. Moreover, from our results we suggest the presence of motile dog sperm subpopulations with an increased sensitivity to fructose and glucose.

Evidence for a functional glycogen metabolism in mature mammalian spermatozoa

The glycogen content in fresh raw dog spermatozoa was 0.22+/-0.03 micromol/mg protein. This matched with the presence of a glycogen-like staining in the head and midpiece. Glycogen levels lowered to 0.05 micromol/mg protein after incubation for 60 min without sugars. Addition of either 10 mM fructose or 10 mM glucose increased glycogen content to 0.70 micromol/mg protein. On the other hand, glycogen synthase activity ratio of fresh dog sperm (0.35+/-0.07, measured in the absence and the presence of glucose 6-P) increased to 0.55 with 10 mM fructose for 20 min, whereas glucose had a smaller effect. Spermatozoa extracts had also a protein of about 100 Kd, which reacted against a rat liver glycogen synthase antibody. This was located in sperm head and midpiece. Furthermore, glycogen phosphorylase activity ratio measured in presence and absence of AMP (0.25+/-0.03 in fresh samples) decreased to 0.15 by 10 mM glucose for 20 min, whereas fructose was less potent in this regard. The maximal effect of glucose and fructose were observed from 10-20 mM onwards. This work is the first indication for a functional glycogen metabolism in mammal spermatozoa, which could play an important role in regulating sperm survival in vivo.

Adenovirus-mediated introduction of DNA into pig sperm and offspring

The ability of adenoviral vectors to transfer DNA into boar spermatozoa and to offspring was tested. Exposure of spermatozoa to adenovirus bearing the E. coli lacZ gene resulted in the transfer of the gene to the head of the spermatozoa. Treatment did not affect either viability or acrosomal integrity of boar sperm. Of the 2-to 8-cell embryos obtained after in vitro fertilization with adenovirus-exposed sperm, 21.7% expressed the LacZ product. Four out of 56 piglets (about 7%) obtained after artificial insemination with adenovirus-exposed spermatozoa were positive in PCR analyses, even though none of the piglets showed the LacZ gene after southern blot analysis. RT-PCR analysis performed in tissues from two positive stillborn piglets showed the presence of the LacZ mRNA in all of the tissues tested. The offspring obtained after mating two positive animals did not show LacZ gene presence. Our results indicate that adenovirus could be a feasible mechanism for the delivery of DNA into spermatozoa, even though the transfer of the transgene may be limited to the first generation.

Effect of semen preparation on IVF of prepubertal goat oocytes

The aim of these experiments was to study the effects of different methods of washing and selection of spermatozoa on the IVF of IVM oocytes from prepubertal goats. Fresh ejaculates from 3 males of proven fertility were processed according to the following treatments: 1) centrifugation in TALP, 2) centrifugation in sucrose-based Ficoll medium, 3) centrifugation in Percoll gradients at 40 and 80%, 4) by swim-up and 5) by dilution of spermatozoa (1:40) in (1:1) TALP. In all 5 treatments spermatozoa were incubated for 45 min with 100 microg/mL of heparin and then added to Fert-TALP. Oocytes were matured for 27 h in TCM-199 supplemented with 20% estrous goat serum (EGS), FSH, LH and estradiol-17beta. Spermatozoa (4x10(6) cells/mL) were coincubated with oocytes in 100 microL of Fert-TALP with hypotaurine for 24 h, after which the oocytes were transferred to a granulosa cells monolayer in TCM-199 plus 10% of EGS for 24 h (48 h post insemination). At 17 h post insemination a sample of sperm-exposed oocytes was taken and stained in lacmoid to observe sperm penetration and the formation of pronuclei. At 48 h post insemination the cleavage rate of oocytes was evaluated. Motility, viability and acrosome status of the spermatozoa were evaluated immediately after the mixing of the ejaculates, after washing and selection treatments, and after incubation with heparin and at 17 h post insemination. The different ejaculate treatments did not affect the penetration and cleavage rates of oocytes. At 48 h post insemination the cleavage rate was 46.9, 36.6 and 29.0% for dilution, Ficoll and swim-up preparations, respectively. Only the swim-up protocol improved sperm motility and viability compared with that of the initial semen sample and with the other sample treatments. At 17 h post insemination the semen parameters were the same for all sperm sample treatments.