scholarly journals 274SIMILARITY OF EMBRYOS PRODUCED BY OVUM PICK-UP AND IN VITRO FERTILIZATION IN IDENTICAL TWIN CATTLE

2004 ◽  
Vol 16 (2) ◽  
pp. 257 ◽  
Author(s):  
K. Imai ◽  
S. Kobayashi ◽  
S. Matoba ◽  
M. Tagawa ◽  
N. Saito

The present study was designed to assess the similarity of follicular development, oocyte quality, and their subsequent development on ovum pick-up (OPU)-IVF in identical twin cattle. Four pairs of identical twin Japanese black cows (A, B pairs at 5 years old and C, D pairs at 3 years old) were kept under the same feeding and environmental conditions. OPU was performed for these cows once a week for seven continuous weeks. OPU was done by using a 7.5-MHz linear transducer with needle (17 G, 530-mm length) connected to an ultrasound scanner (SSD-1200, ALOKA, Tokyo, Japan). Oocytes were evaluated by their cumulus cell morphology, cytoplasmic color, and density. To assess the development, collected COCs were cultured for 20h in TCM-199 supplemented with 5% calf serum (CS) in a microdroplet (volume was adjusted to 5μL/oocyte) at 38.5°C under atmosphere of 5% CO2 in air. After maturation, the COCs were inseminated with frozen-thawed semen collected from the same ejaculation of a single bull. The fertilization was performed with BO solution as described by Imai et al (J. Vet. Med. Sci., 2002, 64(10), 887–891). The zygotes were then cultured in CR1aa supplemented with 5% CS under the same condition of maturation for nine days. Embryo development was assessed by the cleavage rate on Day 2 and the blastocyst production rate on Days 7 to 9 (insemination day=Day 0). Blastocysts were classified according to the IETS creteria. Data were analyzed by ANOVA. A total 56 sessions of OPU were performed in this study. The overall mean number of developing follicles (larger than 2mm in diameter), collected oocytes, and produced blastocysts were 30.3±9.2, 20.1±9.2 and 6.3±3.8 (mean±SD) per session, respectively. The mean number of developing follicles on the day of OPU were significantly different between B and D pairs (38.6±7.5 and 21.9±6.5, P<0.01); however, no significant difference was found within each twin. In oocyte quality, C and D pairs were significantly higher grade than the A pair. The percentages of cleaved oocytes and embryos developed to the blastocyst stage (34±16, 27±10, 41±17 and 39±24) showed no differences among 4 pairs and within each twin. However, the percentage of Grade 1 blastocyst of B pair was significantly lower (P<0.01) than that of other pairs, and C pair was significantly higher (P<0.05) than that of A and D pairs (67±25, 41±22, 93±10 and 71±25; A, B, C and D pairs, respectively). There was no significant difference within twins. These results show little statistical variation between cows of the same genetic background in the production of embryos in vitro.

2005 ◽  
Vol 17 (2) ◽  
pp. 273
Author(s):  
K. Imai ◽  
M. Tagawa ◽  
S. Matoba ◽  
M. Narita ◽  
N. Saito

The present study was designed to assess the renewal of follicular development and oocyte quality after ovum pickup (OPU) in Holstein dry cows. Cows were kept under the same feeding and environmental conditions. In Experiment 1, follicle aspiration (more than 2 mm) by OPU using a 7.5 MHz linear transducer with needle (cova needle, Misawa Medical, Tokyo, Japan) connected to an ultrasound scanner (SSD-1200, ALOKA, Tokyo, Japan) was performed in four cows. After OPU ovaries were observed from Day 4 (Day 0 = the day of OPU) to Day 11 to assess the number of follicles that developed. In Experiment 2, two sessions of OPU (n = 11) were performed with a 7-day interval between to assess the quality of developing follicles and oocytes. Oocytes were evaluated by their cumulus cell morphology, cytoplasmic color, and density. To assess the developmental competence of oocytes, collected cumulus-oocyte complexes (COCs) were cultured for 20 h in TCM-199 supplemented with 5% calf serum (CS) in a microdroplet (volume was adjusted to 5 μL/oocyte) at 38.5°C under atmosphere of 5% CO2 in air. After maturation, the COCs were inseminated with frozen-thawed semen collected from the same ejaculation of a single bull. The fertilization was performed with BO solution as described by Imai et al. (2002 J. Vet. Med. Sci. 64(10), 887–891). The putative zygotes were then cultured in CR1aa supplemented with 5% CS under the same conditions as maturation culture for nine days. Embryo development was assessed by the cleavage rate on Day 2 and the blastocyst formation rate on Days 7 to 9 (the day of insemination = Day 0). Data were analyzed by ANOVA or Student's t-test. In Experiment 1, the mean number of developing follicles (larger than 2 mm in diameter) were increased from Day 4 to Day 11 (Day 4: 19.8 ± 10.0, Day 7: 32.5 ± 9.5; Day 11: 39.5 ± 10.7 (mean ± SD), respectively, P < 0.05). In Experiment 2, the mean number of developing follicles and collected oocytes on the day of OPU were significantly (P < 0.05) different between the first and second sessions (54.2 ± 12.4 and 40.8 ± 12.7, 45.7 ± 20.2 and 27.7 ± 8.7, respectively). The percentage of Grade 1 and 2 oocytes for the first session was significantly lower (P < 0.05) than those for the second session (59.1 ± 8.4 and 69.0 ± 11.8), and no significant differences were found within cleavage and blastocyst rates. The mean numbers of blastocysts obtained per session were 14.2 ± 8.9 and 9.7 ± 6.3 in the first and second sessions, respectively. These results indicate that populations of follicles were increased till Day 11 after OPU, and proportion of normal oocytes were increased in the renewal follicles.


2006 ◽  
Vol 18 (2) ◽  
pp. 270
Author(s):  
C. Hanna ◽  
C. Long ◽  
M. Westhusin ◽  
D. Kraemer

The objectives of this study were to determine whether the percentage of canine oocytes that resume meiosis during in vitro maturation could be increased by either increasing culture duration or by removing approximately one-half of the cumulus cells 24 h after oocytes were placed into culture. Canine female reproductive tracts were collected from a local clinic and ovaries were minced in warm TL-HEPES. Oocytes with a consistently dark ooplasm and at least two layers of cumulus cells were selected, cultured in a basic canine oocyte in vitro maturation medium consisting of TCM-199 with Earl's salts, 2.92 mM Ca-lactate, 20 mM pyruvic acid, 4.43 mM HEPES, 10% fetal calf serum, 1% Penicillin/Streptomycin (GibcoBRL, Grand Island, NY, USA), and 5 μg/mL porcine somatotropin, and incubated at 38.5°C in 5% CO2 in humidified air. Treatment groups were randomly assigned and oocytes were cultured for 60, 84, or 132 h (Basic). From each of these groups, one-half of the oocytes were pipetted through a fine bore pipette to partially remove the cumulus cells 24 h after the start of culture (Basic–1/2). At the end of culture, all oocytes were denuded and the nuclear status was observed with Hoechst 33342 under ultraviolet fluorescence. All data were analyzed by ANOVA with P < 0.05. Since the canine oocyte is ovulated at the germinal vesicle (GV) stage of meiosis and requires up to five days to mature in the oviduct, it was hypothesized that an increased culture time would allow for more oocytes to undergo nuclear maturation to metaphase II (MII). It was also hypothesized that partial removal of cumulus cells would decrease the cumulus cell component in the ooplasm that sustains meiotic arrest, allowing for more oocytes to resume meiosis (RM = germinal vesicle breakdown to MII). Results within each treatment group indicate that there is no significant difference between culture duration and the percent of oocytes that mature to MII. Additionally, there was no significance in the percent of oocytes that resumed meiosis after partial cumulus cell removal. Taken together, these data suggest that neither treatment is effective in canine in vitro maturation systems, given the current maturation culture conditions. Table 1. Nuclear status* of oocytes for three time periods with or without partial cumulus cell removal


2006 ◽  
Vol 18 (2) ◽  
pp. 246
Author(s):  
K. Imai ◽  
M. Tagawa ◽  
S. Matoba ◽  
M. Narita ◽  
K. Kanayama

The present study was designed to assess the recruitment of follicles after ovum pickup (OPU) and dominant follicle (DF) removal on the follicular wave after OPU in Holstein dry cows. Cows were reared under the same feeding and environmental conditions. In Experiment 1, follicle aspiration (>2 mm in diameter) by OPU using a 7.5-MHz linear transducer with needle (COVA needle; Misawa Medical, Tokyo, Japan) connected to an ultrasound scanner (SSD-1200; ALOKA, Tokyo, Japan) was performed in four cows. Then, ovaries were observed after OPU from Day 1 (Day 0 = the day of OPU) to Day 11 to assess the number of follicles developed. In Experiment 2, two sessions of OPU were performed with a 7 day interval between sessions, with or without dominant follicle removal, to assess the quality of developing follicles and oocytes. In the DF removal group, >8-mm follicles were aspirated at Day 5 after the first OPU session, and the same cows without DF removal were designated as a control (n = 4, crossover trial). Oocytes were evaluated by their cumulus cell morphology, cytoplasmic color, and density. To assess the developmental competence of oocytes, Grades 1 and 2 cumulus-oocyte complexes (COCs) were collected, matured, fertilized, and cultured as described by Imai et al. (2002 J. Vet. Med. Sci. 64(10), 887-891). Embryo development was assessed by the cleavage rate on Day 2 and the blastocyst formation rate on Days 7 to 9 (the day of insemination = Day 0). Data were analyzed by ANOVA or Student t-test. In Experiment 1, a dominant follicle (>8 mm in diameter) was developed during Days 3 to 5 after OPU in each donor. The mean number of developing follicles (>2 mm in diameter) were increased from Day 1 to Day 9 (Day 1: 7.5 � 2.1, Day 3: 19.0 � 1.2, Day 5: 23.3 � 9.0, Day 7: 30.3 � 11.0, Day 9: 42.0 � 15.8 and Day 11: 41.0 � 16.7 (mean � SD), P < 0.05). In Experiment 2, there was no difference in the mean number of developing follicles on the day of OPU and collected oocytes between DF removal and control groups (follicles: 47.8 � 23.0 and 39.3 � 6.2; oocytes: 27.0 � 11.6 and 26.5 � 5.4, respectively). The number of Grades 1 and 2 oocytes for the DF removal group was significantly higher (P < 0.05) than that for the control (83.6 � 1.5 and 63.2 � 14.2, respectively), and no significant difference was found within cleavage (60.0 � 37.2, 53.6 � 23.2) and blastocyst rates (34.1 � 33.9, 34.4 � 16.8). These results indicate that populations of follicles were increased till Day 9 after OPU, and the DF removal was effective at increasing oocyte quality in the developing follicles.


2008 ◽  
Vol 20 (1) ◽  
pp. 182 ◽  
Author(s):  
K. Imai ◽  
Y. Inaba ◽  
H. Yoshioka ◽  
Y. Aikawa ◽  
M. Ohtake ◽  
...  

We previously reported that follicular wave synchronization, by removal of the dominant follicle on Day 5 after ovum pickup (OPU), was effective in increasing oocyte quality in the developing follicles (Imai et al. 2006 32th Annual Conference of the IETS, poster presentation no. 277). The current study was designed to examine the effect of superstimulatory treatment to induce subsequent follicular wave synchronization on embryo production by OPU and IVM-IVF-IVC in Holstein dry cows. Cows were reared under the same feeding and environmental conditions, and 2 OPU sessions were conducted in each cow. In the first session, OPU was performed in 8 cows on arbitrary days of the estrous cycle by using a 7.5-MHz linear transducer with needle (Cova needle, Misawa Medical, Tokyo, Japan) connected to an ultrasound scanner (SSD-1200, Aloka, Tokyo, Japan). Follicles larger than 8 mm in diameter were then aspirated and a CIDR was inserted on Day 5 (the day of first OPU session = Day 0). Cows then received 30 mg of FSH (Antrin-R10; Kawasaki Mitaka Pharmaceutical Co., Tokyo, Japan) twice a day from Days 7 to 10 in decreasing doses (6, 6, 4, 4, 3, 3, 2, 2 mg) by i.m. injection. Cloprostenol (PGF; Clopromate C; Sumitomo Pharmaceuticals Co., Tokyo, Japan; 0.75 mg) was administered in the morning of Day 9 (third day of superstimulation). The second OPU session was performed 48 h after PGF administration (Day 11), and only follicles larger than 5 mm in diameter were aspirated. The CIDR was removed from the cows just before OPU. Collected oocytes were evaluated by their cumulus cell morphology, cytoplasmic color, and density. Grades 1 and 2 COC were matured, fertilized, and cultured as described by Imai et al. [2006 J. Reprod. Dev. 52(Suppl.), S19–S29]. Embryo development was assessed by the cleavage rate on Day 2 and by the blastocyst formation rate on Days 7 to 8 (the day of insemination = Day 0). Data were analyzed by Student's t-test. There were no differences in the mean (� SD) number of aspirated follicles or collected oocytes between the first (32.5 � 6.8 and 26.0 � 12.7, respectively) and second (29.3 � 10.4 and 19.0 � 9.4, respectively) OPU sessions (P > 0.1). The percentage of Grade 1 and 2 oocytes for the second OPU session (90.5 � 13.8%) was significantly higher (P < 0.01) than for the first OPU session (63.1 � 6.3%), and significant differences were found for cleavage (79.4 � 14.1, 61.8 � 25.1, P < 0.01) and blastocyst rates (68.1 � 16.7, 24.2 � 22.3, P < 0.001) between sessions. The mean numbers of blastocysts obtained per session were 4.3 � 2.9 and 12.8 � 8.7 in the first and second sessions, respectively (P < 0.01). These results indicate that superstimulatory treatment and subsequent follicular wave synchronization were effective on in vitro embryo production by increasing the oocyte quality.


Zygote ◽  
2005 ◽  
Vol 13 (2) ◽  
pp. 177-185 ◽  
Author(s):  
A. Nader Fatehi ◽  
Bernard A.J. Roelen ◽  
Ben Colenbrander ◽  
Eric J. Schoevers ◽  
Bart M. Gadella ◽  
...  

The present study was conducted to evaluate the function of cumulus cells during bovine IVF. Oocytes within cumulus–oocyte complexes (COCs) or denuded oocytes (DOs) were inseminated in control medium, or DOs were inseminated in cumulus cell conditioned medium (CCCM). DOs exhibited reduced cleavage and blastocyst formation rates when compared with intact COCs. The reduced blastocyst formation rate of DOs resulted from reduced first cleavage but subsequent embryo development was not changed. Live-dead staining and staining for apoptotic cells revealed no differences in blastocysts from oocytes fertilized as COC or DO. Fertilization of DOs in CCCM partially restored the cleavage rate, suggesting that factors secreted by cumulus cells are important for fertilization but that physical contact between oocytes and cumulus cells is required for optimal fertilization and first cleavage. Exposure of COCs to hydrogen peroxide shortly before fertilization reduced the cleavage rate, but did not lead to enhanced death of cumulus cells or oocyte death. Exposure of DOs to hydrogen peroxide, however, resulted in oocyte death and a complete block of first cleavage, suggesting that cumulus cells protect the oocyte against oxidative stress during fertilization.


2008 ◽  
Vol 20 (1) ◽  
pp. 115
Author(s):  
L. Attanasio ◽  
A. De Rosa ◽  
L. Boccia ◽  
R. Di Palo ◽  
G. Campanile ◽  
...  

Although removal of cumulus cells improves the efficiency of vitrification of buffalo (Bubalus bubalus) in vitro-matured (IVM) oocytes (Gasparrini et al. 2007 Anim. Reprod. Sci. 98, 335–342), the lack of cells impairs the fertilization process. Therefore, the aim of the present work was to evaluate the influence of a somatic support during in vitro fertilization (IVF) of buffalo vitrified denuded matured oocytes. Since IVF on a cumulus cells monolayer was inefficient, we verified the effects of co-culture with cumulus-enclosed oocytes (COCs). IVM buffalo oocytes (n = 316) were vitrified by the Cryotop� method (Kuwayama and Kato 2000, J. Assist. Reprod. Genet. 17, 477 abst) that was recently proven suitable for buffalo oocyte cryopreservation (Attanasio et al. 2006 Reprod. Domest. Anim. 41, 302–310). Denuded buffalo oocytes were equilibrated in 10% ethylene glycol (EG) and 10% dimethyl sulfoxide (DMSO) for 3 min, transferred into 20% EG and 20% of DMSO in TCM199 with 20% fetal calf serum (FCS) + 0.5 m sucrose, loaded on Cryotops, and plunged into liquid nitrogen within 25 s. For warming, oocytes were exposed for 1 min to 1.2 m sucrose and then to decreasing concentrations of the sugar (0.6, 0.4, 0.3 m for 30 s) in TCM199 + 20% FCS. Oocytes were rinsed and allocated to IVM drops for 1.5 h. Survival rate was evaluated at this point and the oocytes that had survived (292/316 = 92.4%) were split into 2 fertilization groups: (A) approximately 5 buffalo oocytes per 50-µL drop of IVF medium, and (B) approximately 3 buffalo oocytes + 3 bovine fresh COCs per 50-µL drop of IVF medium. Since buffalo COCs easily lose their cells following IVF, for better identification we used bovine COCs that have a brighter and more compact cumulus mass. In vitro fertilization and culture were carried out as previously described (Gasparrini et al. 2007). As control, buffalo oocytes (n = 104) were in vitro-matured, fertilized, and cultured up to the blastocyst stage. On Day 1, survival rate was evaluated in the two vitrification groups; cleavage and blastocyst rates were recorded on Days 5 and 7, respectively, in all groups. The experiment was repeated 4 times. Differences in the percentages of survival, cleavage, and blastocyst formation among treatments were analyzed by chi-square test. Within vitrification groups, despite similar survival rates on Day 1 (90.6% v. 93.3%, respectively, in Groups A and B), cleavage rate was significantly improved in Group B compared to Group A (59.2% v. 45.4%, respectively; P < 0.01). Interestingly, the cleavage rate in Group B was not significantly different from that recorded in the control group (71.0%). Although blastocysts were produced in both vitrification groups (3.6% v. 4.1%, respectively, in Groups A and B), the yield was significantly lower than that of the control group (29.0%, P < 0.01). In conclusion, co-culture with bovine COC during fertilization improves the capability of buffalo denuded vitrified oocytes to cleave.


2002 ◽  
Vol 45 (6) ◽  
pp. 547-556
Author(s):  
N. R. Mtango ◽  
M. D. Varisanga ◽  
D. Y. Juan ◽  
P. Wongrisekeao ◽  
T. Suzuki

Abstract. This study was designed 1) to determine the effectiveness of two in vitro maturation (IVM) media (tissue culture medium [TCM] and modified synthetic oviduct fluid supplemented with amino acids [mSOFaa]), 2) to compare the effects of two in vitro fertilization (IVF) media (modified Tris-buffered medium [mTBM] and mSOFaa) on the developmental competence of pig oocytes, and 3) to test the activation ability of IVM pig oocytes matured in TCM or mSOFaa, electroactivated and cultured in mSOFaa. The nuclear maturation rates were similar between IVM media (91.0 % vs. 89.0 %). A similar result was obtained when the activation rates were 54.2 % in TCM and 56.0 % in mSOFaa, and the blastocyst rates were 7.9 % and 6.1 %, respectively. There was no significant difference between mSOFaa and mTBM in the percentage of embryos with two pronuclei 33.2 % vs. 13.8 % or polypronuclei 5.3 % vs. 13.4 %. The cleavage rate was the same in both media. The medium mSOFaa gave a significantly higher (P< 0.05) blastocyst rate than mTBM (12.7 % vs. 3.9 %). We concluded that mSOFaa can enhance in vitro maturation, fertilization and culture of pig oocytes.


2017 ◽  
Vol 114 (29) ◽  
pp. E5796-E5804 ◽  
Author(s):  
Ye Yuan ◽  
Lee D. Spate ◽  
Bethany K. Redel ◽  
Yuchen Tian ◽  
Jie Zhou ◽  
...  

Assisted reproductive technologies in all mammals are critically dependent on the quality of the oocytes used to produce embryos. For reasons not fully clear, oocytes matured in vitro tend to be much less competent to become fertilized, advance to the blastocyst stage, and give rise to live young than their in vivo-produced counterparts, particularly if they are derived from immature females. Here we show that a chemically defined maturation medium supplemented with three cytokines (FGF2, LIF, and IGF1) in combination, so-called “FLI medium,” improves nuclear maturation of oocytes in cumulus–oocyte complexes derived from immature pig ovaries and provides a twofold increase in the efficiency of blastocyst production after in vitro fertilization. Transfer of such blastocysts to recipient females doubles mean litter size to about nine piglets per litter. Maturation of oocytes in FLI medium, therefore, effectively provides a fourfold increase in piglets born per oocyte collected. As they progress in culture, the FLI-matured cumulus–oocyte complexes display distinctly different kinetics of MAPK activation in the cumulus cells, much increased cumulus cell expansion, and an accelerated severance of cytoplasmic projections between the cumulus cells outside the zona pellucida and the oocyte within. These events likely underpin the improvement in oocyte quality achieved by using the FLI medium.


Author(s):  
Maryam Adib ◽  
Seyed Morteza Seifati ◽  
Mahmood Dehghani Ashkezari ◽  
Arezoo Khoradmehr ◽  
Roshan Rezaee-Ranjbar-Sardari ◽  
...  

Background: To increase the results of infertility treatment, many efforts have been made to improve the treatment methods. As assisted reproductive technology is mainly using cell culture methods, one of the approaches to improve this technology is conditioned medium from different sources. It is desirable to apply in vitro maturation (IVM) and use oocytes from normal cycles instead of stimulating ovulation. Objective: To investigate the effect of human cumulus cell condition medium (hCCCM) on the IVM of immature mouse oocytes and morphology. Materials and Methods: In this experimental study, 240 germinal vesile oocytes were collected from four-six wk-old mice after 48 hr of 5IU pregnant mare serum gonadotropin (PMSG) injection and cultured in hCCCM (test group, n = 120) and DMEM + 20% FBS (control group, n = 120). The IVM rates and changes in perivitelline space (PVS) and shape were investigated at 8, 16, and 24 hr following the culture. The mature (MII) oocytes were subjected to in vitro fertilization (IVF) and the fertilization rate was assessed in three days. Results: A significant difference was observed between the maturation rates in the hCCCM and control groups (24.16% vs 0%; p = 0.001), as well as morphologic changes between the two groups (p = 0.04, p = 0.05). The development rate for MII oocytes attained from IVM in the hCCCM group was 27.58% (2-cell) and 6.89% (4-cell). Data displayed that hCCCM is an effective medium for oocytes maturation compared to the control medium. Conclusion: hCCCM supports oocyte in vitro growth and maturation. Moreover, hCCCM changes the oocyte shape and size of perivitelline space. Key words: Germinal vesicle, Cumulus cell, Conditioned medium, In vitro fertilization, In vitro maturation, Oocyte.


2007 ◽  
Vol 19 (1) ◽  
pp. 179
Author(s):  
R. Morató ◽  
D. Izquierdo ◽  
M. J. Palomo ◽  
B. Anguita ◽  
A. R. Jiménez-Macedo ◽  
...  

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


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