71 VITRIFICATION OF BOVINE OOCYTES IN MEDIA WITH GLYCEROL + ETHYLENE GLYCOL BEFORE AND AFTER IN VITRO MATURATION

2008 ◽  
Vol 20 (1) ◽  
pp. 116
Author(s):  
L. G. Devito ◽  
C. B. Fernandes ◽  
H. N. Ferreira ◽  
F. C. Landim-Alvarenga
Keyword(s):  
Ethylene Glycol ◽  
Liquid Nitrogen ◽  
In Vitro Maturation ◽  
Calf Serum ◽  
Quiescent State ◽  
Developmental Potential ◽  
Immature Oocytes ◽  
Nitrogen Vapor ◽  
Bovine Oocytes

The cryopreservation process aims to keep the cellular metabolism in a quiescent state for an indeterminate length of time. In mammals, oocyte cryopreservation success is important for the establishment of genetic banks. The objective of the present experiment was to evaluate the effect of vitrification on oocyte meiotic ability and the integrity of the metaphase plate in immature and in vitro-matured bovine oocytes. Bovine cumulus–oocytes complexes (COCs) were harvested from slaughterhouse ovaries and randomly divided into 3 groups: (G1) non-vitrified oocytes subjected to in vitro maturation, (G2) immature oocytes vitrified and then subjected to in vitro maturation after warming, and (G3) in vitro-matured oocytes subjected to vitrification. For in vitro maturation, oocytes were incubated for 22 h in 5% CO2 in air in TCM-199 with fetal calf serum, estradiol, LH, FSH, pyruvate, and gentamicin. For vitrification, the oocytes were exposed to the cryoprotectors in three steps: solution 1 containing 1.4 m glycerol in PBS for five min, and then solution 2 containing 1.4 m glycerol and 3.6 m ethylene glycol in PBS for another five min. After exposure to the second solution, the oocytes were transferred to 30-µL drops of solution 3 containing 3.4 m glycerol and 4.6 m ethylene glycol, loaded (5 oocytes per straw) in less than 1 min into 0.25-mL straws between two columns of 0.5 m galactose in PBS separated by two air bubbles, and immediately set in liquid nitrogen vapor. After 1 min of equilibration in liquid nitrogen vapor, the straws were immersed in liquid nitrogen. Warming was performed by holding the straws for 10 s in air, followed by 10 more s in a water bath at 20–22�C. The straws were then shaken 5 to 8 times to mix the bubbles (movement similar to that for a thermometer) and left horizontally for 6 to 8 min at room temperature. The rates of metaphase II and degeneration were analyzed by ANOVA followed by the Student t-test. The oocytes were stained with 100 µg mL–1 Hoechst 33342 and examined in an inverted microscope equipped with fluorescent light (UV filters 535 and 617 mm). Three different routines were realized with a total of 90 oocytes per group. The metaphase II rates in G1 (48/90, 53.3%) and G3 (42/90, 46.6%) were statistically the same (P e 0.05), but were higher (P d 0.05) than in G2 (0/90, 0%). The degeneration rates were: G1 (18/90, 20%), G2 (77/90, 85.6%), and G3 (7/90, 7.8%). The vitrification procedure damaged mainly the immature oocytes, since in the G2 the degeneration rate was higher and the oocytes were not able to resume meiosis. Meanwhile, when oocytes were vitrified after in vitro maturation, the metaphase II rate was similar to the one observed in IVM oocytes not subjected to vitrification. This indicates that the vitrification procedure performed in this experiment did not damage the structure of the metaphase II plate. However, more studies are necessary to predict the developmental potential of these in vitro-matured oocytes.

44 THE EFFECT OF SUCROSE CONCENTRATION FOR SINGLE-STEP DILUTION ON THE VIABILITY OF CRYOTOP-VITRIFIED IN VITRO-PRODUCED BOVINE EMBRYOS

2015 ◽  
Vol 27 (1) ◽  
pp. 115
Author(s):  
S. Kondo ◽  
K. Imai ◽  
O. Dochi
Keyword(s):  
Ethylene Glycol ◽  
Dimethyl Sulfoxide ◽  
Liquid Nitrogen ◽  
Sucrose Concentration ◽  
Calf Serum ◽  
Single Step ◽  
Bovine Embryos ◽  
Vitrification Solution ◽  
Phosphate Buffered Saline

The aim of this study was to test sucrose concentrations for single-step dilution on the viability of vitrified in vitro-produced bovine embryos. Blastocysts (n = 173, 7 to 8 days after fertilization) were vitrified using the Cryotop (Kitazato, Tokyo, Japan) method placement by incubating the blastocysts in Dulbecco's phosphate buffered saline supplemented with 20% calf serum, 7.5% ethylene glycol, and 7.5% dimethyl sulfoxide for 3 min and then transferring into vitrification solution (Dulbecco's phosphate buffered saline supplemented with 20% calf serum, 16.5% ethylene glycol, 16.5% dimethyl sulfoxide, and 0.5 M sucrose). Each embryo was placed on a Cryotop with minimum volume of vitrification solution, and then the Cryotop was plunged into liquid nitrogen. Total time from placement in vitrification solution to plunging into liquid nitrogen was 1 min. The blastocysts were warmed by incubation in the single-step dilution medium for 5 min [0 M sucrose (n = 42), 0.25 M sucrose (n = 44), 0.5 M sucrose (n = 43), and 1.0 M sucrose (n = 44)] at 38.0°C. After dilution, the embryos were washed in TCM-199 supplemented with 20% calf serum and 0.1 mM β-mercaptoethanol and were cultured for 72 h in the same medium at 38.5°C in an atmosphere of 5% CO2. The rates of re-expanded blastocysts and hatched blastocysts were determined at 24 and 72 h after warming, respectively. Data were analysed using the chi-squared test. The percent of re-expanded blastocysts at 24 h after warming in dilution medium supplemented with any level of sucrose was significantly higher (P < 0.05) than in blastocysts warmed without sucrose (Table 1). The hatched blastocyst rate of embryos at 72 h after warming in dilution medium with 0.5 M sucrose was significant higher than that with no sucrose. There were no differences in hatched blastocyst rates between the sucrose concentrations supplemented to the dilution medium. These results suggest that embryos vitrified by the Cryotop method can be diluted in single-step dilution using 0.25, 0.5, or 1.0 M sucrose supplemented to the medium. Table 1.The effect of sucrose concentration for single-step dilution on the viability of Cryotop vitrified in vitro-produced bovine embryos

115 ADDITION OF ETHANOL AT SUB-STRESS CONCENTRATIONS DURING IN VITRO MATURATION OF BOVINE OOCYTES IMPROVES BLASTOCYST CRYOTOLERANCE

2010 ◽  
Vol 22 (1) ◽  
pp. 216 ◽  
Author(s):  
M. A. M. M. Shehab-El-Deen ◽  
J. L. M. R. Leroy ◽  
D. Maes ◽  
A. Van Soom
Keyword(s):  
In Vitro Maturation ◽  
Embryo Quality ◽  
Calf Serum ◽  
Ethanol Stress ◽  
Stress Concentrations ◽  
Low Concentrations ◽  
Carry Over ◽  
Bovine Oocytes

In in vitro experiments, the percentage of bovine oocytes that develops to the blastocyst stage is much lower compared with the in vivo counterparts. The quality of the oocyte is the main factor affecting blastocyst yield. Moreover, in vitro-produced bovine embryos are more sensitive to cryo-injuries than those produced in vivo. Exposure of oocytes to sub-lethal concentrations of stressors may enhance their quality through upregulation of intracellular shock proteins. We aimed to evaluate whether addition of ethanol at low concentrations (0.27 or 0.53%) during oocyte maturation could have a carry-over effect on embryo quality and could subsequently affect embryo cryotolerance. Cumulus-oocyte complexes (n = 934) were matured in serum-free TCM199 plus 20 ng mL-1 of epidermal growth factor (control), supplemented with ethanol 0.27% (treatment 1) or 0.54% (treatment 2), in 3 replicates. After fertilization, the presumptive zygotes were cultured for 6 days in modified SOF medium supplemented with 5% fetal calf serum (FCS); the number of blastocysts was recorded and classified. Then, expanded blastocysts were cryopreserved by open pulled straw vitrification using the 2-step approach described by Vajta G et al. (1998 Mol. Reprod. Dev. 51, 53-58). After 24 h, vitrified embryos were warmed and cultured in groups of <25 per 50 μL droplet of modified SOF medium with 5% FCS under mineral oil for 48 h and examined for re-expansion and hatching. Differences between the groups in blastocyst yield were analyzed by ANOVA; differences in survival rates between the groups were analyzed using logistic regression analysis. For all statistical models, group was included as fixed effect, and also the effect of replicate was included. Differences were considered to be statistically significant when P < 0.05. Addition of ethanol to in vitro maturation media had no significant effects on blastocyst yield on 7 dpi. Also, addition of ethanol at 0.27% did not affect blastocyst cryotolerance. However, addition of ethanol 0.54% to in vitro maturation media significantly increased the survival of bovine blastocysts after vitrification (P < 0.01; Table 1). The results of the present study indicate that maturation of oocytes under ethanol stress at low concentrations has carry-over effects on embryo quality, leading to improved cryotolerance. Table 1.Survival percentage (mean ± SE) of vitrified expanded bovine blastocysts matured in the presence of sub-stress concentrations of ethanol The authors thank I. Lemahieu and P. Vandamme for their excellent technical support. This research was supported by the special research fund, Ghent University (Grant, BOF/DOS No. 01W05706).

Zona pellucida birefringence correlates with developmental capacity of bovine oocytes classified by maturational environment, COC morphology and G6PDH activity

2012 ◽  
Vol 24 (4) ◽  
pp. 568 ◽  
Author(s):  
Eva Held ◽  
Eva-Maria Mertens ◽  
Abdollah Mohammadi-Sangcheshmeh ◽  
Dessie Salilew-Wondim ◽  
Urban Besenfelder ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Zona Pellucida ◽  
In Vitro Maturation ◽  
Immature Oocytes ◽  
Developmental Capacity ◽  
Bovine Oocytes ◽  
Scanning Electron

In the present study we aimed to analyse structural changes during in vitro maturation of the bovine zona pellucida (ZP) by scanning electron microscopy (SEM) ands zona pellucida birefringence (ZPB). Here we show that alterations during in vitro maturation invasively analysed by SEM are reflected in ZPB. In vivo-matured oocytes displayed significantly lower birefringence parameters and significantly higher blastocyst rates compared with in vitro-derived oocytes (39.1% vs 21.6%). The same was observed for in vitro-matured oocytes with cumulus–oocyte complex (COC) Quality 1 (Q1) compared with Q3-COCs with respect to zona birefringence and developmental capacity. Immature oocytes with Q1-COCs displayed higher ZPB values and a higher developmental capacity to the blastocyst stage (27.7% vs 16.9%) compared with immature Q3-COCs. Considering in vitro-matured oocytes, only those with Q1-COC showed a trend for ZPB similar to in vivo-matured oocytes. Therefore, a decreasing trend for ZPB during in vitro maturation seems to be typical for high-quality oocytes and successful cytoplasmic maturation. In accordance, fully-grown immature oocytes reached significantly higher blastocyst rates (32.0% vs 11.5%) and lower ZPB values compared with still-growing ones. In conclusion, we successfully evaluated the applicability of zona imaging to bovine oocytes: alterations during in vitro maturation invasively analysed by scanning electron microscopy were reflected in the birefringence of the zona pellucida of bovine oocytes affecting developmental capacity at the same value. Therefore ZPB measurement by live zona imaging has potential to become a new tool to assess correctness of in vitro maturation and to predict developmental competence.

36 EFFECT OF cAMP MODULATORS DURING OOCYTE IN VITRO MATURATION ON GAP JUNCTIONAL ACTIVITY OF VITRIFIED BOVINE OOCYTES

2016 ◽  
Vol 28 (2) ◽  
pp. 148
Author(s):  
C. A. S. Monteiro ◽  
G. R. Leal ◽  
H. F. R. A. Saraiva ◽  
A. J. R. Camargo ◽  
P. M. S. Rosa ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Fluorescence Intensity ◽  
In Vitro Maturation ◽  
Staining Pattern ◽  
Control Group ◽  
Immature Oocytes ◽  
Junctional Activity ◽  
Gap Junctional ◽  
Bovine Oocytes

Oocyte cryopreservation is a strategic tool for in vitro embryo production, but low rates of cryosurvival are reported for bovine oocytes. Simulated physiological oocyte maturation system (Albuz et al. 2010 Hum. Reprod. 25, 12) uses cAMP modulators to increase oocyte competence by the extension of meiosis block and gap junctional communications activity. The aim of this study was to investigate the effect of simulated physiological oocyte maturation system on gap junctional activity of vitrified bovine oocytes. Oocytes from slaughterhouse ovaries were divided into 4 groups: C (control: fresh immature oocytes); V (vitrified immature oocytes); PM-V (vitrified oocytes after a 2-h pre-in vitro maturation phase – in the presence of AMPc modulators, 100 μM Forskolin, and 500 μM IBMX); and PM (fresh immature oocytes subjected to pre-in vitro maturation). Viable oocytes (n = 404 obtained from 4 replicates) were stained with Calcein-AM using the protocol of Thomas et al. (2004 Biol. Reprod. 71(4), 1142–1149) in order to measure gap junctions activity. Images were captured in fluorescence microscope, and fluorescence intensity was analysed with ImageJ software. Mean fluorescence intensity of each group was normalized to control group to obtain relative intensity value. Means were compared by Kruskal-Wallis test and Dunn post-test. A second analysis was performed considering the percentage of each staining pattern (low, middle, and high intensity) for each group. Results were analysed using Fisher exact test. All statistical analysis were performed in GraphPad Instat program with 5% significance level. Results demonstrated that all treatments induced an increase (P < 0.05) in fluorescence intensity (V: 1.76 ± 1.13; PM-V: 1.58 ± 0.98; PM: 1.38 ± 0.94) compared with control (C: 1.00 ± 0.48). Regarding the staining patterns analyses, immature vitrified oocytes (V group) differed from control group in middle and low patterns (G1, calibrator – high: 11.2%ab, middle: 43.8%a, low: 44.9%a; G2 – high: 8.2%ab, middle: 63.9%b, low: 27.9%b; G3 – high: 16.3%a, middle: 42.3%a, low: 41.3%a; G4 – high: 6.7%b, middle: 53.9%ab, low: 39.3a). In conclusion, unexpectedly, vitrification also increased gap junctional activity, as was found for pre-in vitro maturation group. However, staining pattern analysis results showed only vitrified group was different from control, suggesting vitrified and pre-in vitro maturation groups could have gap activity affected by different ways. This research was supported by FAPERJ (E26/111.61/2013) and CAPES.

scholarly journals Meiotic Status Does Not Affect the Vitrification Effectiveness of Domestic Cat Oocytes

Animals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1371
Author(s):  
Natalia Sowińska ◽  
Jennifer Zahmel ◽  
Wojciech Niżański ◽  
Romy Hribal ◽  
Lorena Fernandez-Gonzalez ◽  
...  
Keyword(s):  
In Vitro Maturation ◽  
Fetal Calf Serum ◽  
Calf Serum ◽  
Toxicity Assessment ◽  
Domestic Cat ◽  
Developmental Potential ◽  
Vitro Fertilization ◽  
Negative Effect ◽  
Meiotic Competence

Cryopreservation is important for animal fertility and biodiversity. Unfortunately, cryopreservation of feline oocytes is still an experimental technique. The aims of this study were to analyze the potential toxicity of the cryoprotectants in the vitrification solution (VS) on cat oocytes and to investigate whether the meiotic status of oocytes influences their developmental potential after vitrification. Two experiments were conducted with the VS composed of 20% ethylene glycol, 20% dimethyl sulfoxide, 20% fetal calf serum, 1.5 M trehalose, and 10% Ficoll PM-70: (1) toxicity assessment of the VS on immature cumulus oocyte complexes (COCs), and subsequently in vitro maturation (IVM) and in vitro fertilization; (2) assessment of the influence of the meiotic status on vitrification effectiveness, where immature and in vitro matured COCs were vitrified on the Cryotop. After rewarming, vitrified oocytes were subjected to IVM (immature) and intracytoplasmic sperm injection (ICSI) with fresh epididymal sperm. The toxicity test revealed no negative effect of oocyte exposure to the applied VS on their developmental potential (p > 0.05). Although the vitrification procedure itself significantly reduced the meiotic competence of oocytes, their meiotic status before vitrification (immature vs. in vitro matured) did not influence fertilization and morula rates. The only parameter affected by vitrification was the rate of oocytes suitable for ICSI, which was significantly lower for immature oocytes. Regardless of the meiotic status of vitrified oocytes, morphologically normal morulae were obtained. Moreover, the two meiotic stages examined are suitable for vitrification, with mature oocytes being a better choice when a well-equipped laboratory is available.

scholarly journals 46 VITRIFICATION OF IMMATURE AND MATURE BOVINE OOCYTES

2017 ◽  
Vol 29 (1) ◽  
pp. 130
Author(s):  
P. T. Hardin ◽  
F. A. Diaz ◽  
B. A. Foster ◽  
E. J. Gutierrez ◽  
K. R. Bondioli
Keyword(s):  
Ethylene Glycol ◽  
Dimethyl Sulfoxide ◽  
Maturation Stage ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Exact Test ◽  
Immature Oocytes ◽  
Commercial Source ◽  
Bovine Oocytes

While vitrification has become a valuable system used in oocyte and embryo preservation, there is still much to be learned in optimizing this protocol. Both mature and immature oocytes can be vitrified but each presents challenging aspects. Mature oocytes have microfilaments that are not yet developed in immature oocytes, which are fragile and may be disrupted by ice crystal formation during freezing. Further, currently many different cryoprotectants are used in different concentrations, most being combinations of dimethyl sulfoxide (DMSO), glycerol, and ethylene glycol. This study aimed to determine if vitrification solutions composed of ethylene glycol and either dimethyl sulfoxide or glycerol resulted in more-competent post-thaw oocytes, and to determine if maturation stage affected optimal vitrification solution. As validation of the IVF protocol, fresh mature oocytes from a commercial source were fertilized and proportion, with pronuclei formation 48 h post-IVF was recorded. Two experiments evaluated 2 cryoprotectant solutions by analysing post-vitrification and thaw competence of in vitro-fertilized oocytes to form pronuclei. Oocytes in both studies were exposed to 2 sequential vitrification solutions containing 10% DMSO or glycerol, 10% ethylene glycol and 0.5 M sucrose, and then 20% DMSO/glycerol and ethylene glycol and 0.5 M sucrose, before vitrification on cryolocks. In the first study, immature bovine oocytes (n = 200) were vitrified. Following thawing and IVM, they were analysed for pronuclei formation, with 8.49% and 0% fertilization following vitrification in DMSO and glycerol, respectively (P < 0.01). In the second study, mature oocytes were vitrified (n = 200), thawed, and fertilized using the same methods as in study 1. In total, 12.62% and 3.4% of the mature oocytes were successfully fertilized following vitrification in DMSO and glycerol, respectively (P < 0.05). Fisher’s exact test was used for all statistics in both studies. These results suggest that DMSO in combination with ethylene glycol may be superior to glycerol for vitrification of both immature and mature bovine oocytes.

292 INHIBITION OF HSP90 AGGRAVATES THE EFFECTS OF HEAT SHOCK ON DEVELOPMENTAL COMPETENCE OF BOVINE OOCYTES

2015 ◽  
Vol 27 (1) ◽  
pp. 235
Author(s):  
E. D. Souza ◽  
N. C. Rabelo ◽  
T. D. Araujo ◽  
C. M. Assunção ◽  
C. C. R. Quintão ◽  
...  
Keyword(s):  
Heat Shock ◽  
In Vitro Maturation ◽  
Calf Serum ◽  
Developmental Competence ◽  
Cleavage Rate ◽  
Oocyte Developmental Competence ◽  
Significant Difference ◽  
Blastocyst Rate ◽  
Bovine Oocytes

The heat shock protein 90kDa (HSP90) is a chaperone involved in protein homeostasis under normal and stress conditions. Its inhibition by 17-(allylamino)-17-demethoxygeldanamycin (17AAG, Sigma, St. Louis, MO, USA) for 12 or 24 h during in vitro maturation reduces the oocyte's ability to develop after in vitro fertilization (Souza et al. 2014 Reprod. Fert. Dev. 26, 197). This study aimed to evaluate the effect of treatment with 17AAG during the heat shock on oocyte developmental competence. Immature bovine COC were randomly allocated in 4 treatments during IVM: control = no heat shock or 17AAG; HS = heat shock (41.5°C) for the first 12 h of IVM; 17AAG = 2 µM 17AAG for the first 12 h of IVM; and 17AAG + HS = 2 µM 17AAG plus heat shock for the first 12 h of IVM. In vitro maturation was performed in Nunc plate containing 400 µL of TCM199 medium (Invitrogen, Carlsbad, CA, USA) supplemented with porcine FSH (Hertape Calier, Juatuba, Brazil) and 10% oestrus cow serum under 5% CO2 in air, 95% humidity, and 38.5°C for 24 h. Semen was processed by Percoll gradient (Nutricell, Campinas, Brazil) and oocytes were in vitro fertilized for 20 h with 2 × 106 spermatozoa mL–1 under the same IVM atmospheric conditions. Presumptive zygotes were completely denuded in a PBS solution with 0.1% hyaluronidase and then cultured in wells with 500 µL of modified CR2aa medium supplemented with 2.5% fetal calf serum (Nutricell) in an incubator at 38.5°C under 5% CO2, 5% O2, 90% N2, and saturated humidity. Cleavage rate was evaluated 72 h postfertilization and blastocyst rate was evaluated at Day 7 (D7) and 8 (D8). Data from 7 replicates were submitted to analysis of variance and means were compared by Student Newman Keul's test. There was no difference (P > 0.05) on cleavage rate among treatments. Heat shock or treatment with 17AAG, both for 12 h of IVM, decreased (P < 0.05) the blastocyst rate at D7 and D8 when compared to control but no significant difference between HS and 17AAG treatments was found (Table 1). However, the lowest (P < 0.05) blastocyst rate at D7 and D8 was achieved when oocytes were submitted simultaneously to 17AAG and heat shock for 12 h of IVM (17AAG + HS treatment, Table 1). In conclusion, the treatment with 17AAG during IVM worsens the deleterious effect of heat shock on oocyte developmental competence and suggests that HSP90 may also play role on cellular protection during heat shock in bovine oocytes. Table 1.Cleavage and blastocyst (Bl) rates at D7 and D8 for control, 17AAG, Heat Shock (HS), and 17AAG plus HS treatments Financial support comes from CNPq, FAPEMIG, and FAPES.

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