Latrunculin a Enhances the Parthenogenetic Developmental Potentials of Electrically Activated Porcine Oocytes Matured In Vitro

2011 ◽  
Vol 236-238 ◽  
pp. 2548-2553
Author(s):  
Jian Hui Wang ◽  
Dong Min Liu ◽  
Yong Le Liu

The present study was carried out to determine the effect of latrunculin A (Lat-A) and FBS on the developmental potentials of electrically activated porcine oocytes maturedin vitro. Electrically activated MII oocytes were incubated for 2 hr in mPZM-3 supplemented either with 0、20 nM、1 μM Lat-A or 2.2 μg/ml cytochalasin B (CB). They were then removed and placed in mPZM-3 with or without 10% FBS (addition) on Day 4 for further development. The nuclear activation rate was significantly improved when activated oocytes were cultured in mPZM-3 with Lat-A (P<0.05). At higher dosage (1μM) of Lat-A, the extrusion of second polar body was inhibited while the cleavage rate increased significantly (P<0.05). Significant interaction between Lat-A and FBS supplementation on Day 4 was observed duringin vitrodevelopment (P<0.05). The hatched blastocyst rates and cell numbers per blastocyst were significantly enhanced with the supplementation of FBS (P<0.05). The blastocyst formation, hatched blastocyst rates and mean cell numbers per blastocyst of 1 μM Lat-A treatment with FBS supplementation were significantly higher than those of 20 nM Lat-A and CB treatments with FBS supplementation (P<0.05), but the individual effect of FBS supplementation was not observed on blastocyst formation in 20 nM and 1 μM Lat-A treatments. While significant difference was seen in blastocyst formation and cell numbers per blastocyst among all the treatments without FBS supplementation (P<0.05). These results indicate that Lat-A especially at the dosage of 1 μM can significantly improve the developmental potential of electrically activated porcine oocytes, and the FBS supplementation on Day 4 of development have an additional effect on porcine embryo development.

2016 ◽  
Vol 28 (2) ◽  
pp. 209
Author(s):  
M. Nkadimeng ◽  
E. van Marle-Koster ◽  
K. P. M. Lekola ◽  
M. L. Mphaphathi ◽  
M. M. Seshoka ◽  
...  

Heat stress during IVF is associated with reduced fertility in cattle oocytes. It may, however, enhance thermo-tolerance or cause detrimental effects on a variety of cell types or organisms, depending on the duration and intensity of the thermal challenge. The aim of this study was to evaluate the developmental potential of cumulus-oocyte complexes (COC) matured for 18 or 24 h and incubated at 39°C or 41°C. A total of 1000 immature oocytes were collected at slaughter from indigenous South African cow ovaries. The COC were randomly allocated (100/treatment) into 2 maturation times (18 or 24 h) and cultured in M199 + FSH-LH-estradiol medium under oil at 100% humidity and 5% CO2 at 39°C or 41°C. Post maturation, oocytes were subjected to normal subsequent embryo conditions. The Bracket and Oliphant medium was used for IVF. All matured oocytes were fertilised for 6 h with frozen-thawed Nguni bull semen at a concentration of 265 × 106. The presumptive zygotes from each treatment were cultured into SOF-BSA medium under oil and incubated at 39°C for assessment of cleavage rate 48 h post IVF. After Day 7 of culture, blastocyst were stained (Hoechst 33323) for nuclei cell count. Statistical analyses was performed using Genstat® software of SAS (SAS Institute, Cary, NC, USA; P < 0.05). Oocytes that were matured for 18 h in 41°C resulted in more 8-cell embryos (41%) compared with those incubated at 39°C (21.6%). However, no difference was observed for cleavage rate at both maturation times and incubation temperatures (41 or 39°C). There was more morula formation from oocytes matured for 18 h (19.6%) and 24 h (19.0%) at 41°C compared to 39°C (8.4%) group. The results further showed more blastocyst formation during 18 h at 41°C (15.2%) than at 39°C (7.4%) and during 24 h at 41°C (11.2%), 39°C (11.4%). However there was no difference in the nuclei cell number during 18 h at 41°C (45.2), 24 h (45.8), and 18 h at 39°C (43.4) of maturation. Thus, there was a significant difference in the nuclei cell numbers at 24 h on 39°C (n = 133.2) and 41°C (n = 45.8). In conclusion, oocytes that were matured for 18 and 24 h at 41°C or for 18 h at 39°C developed further to blastocyst stage on in vitro embryo production, however, with low nuclei cell numbers due to accelerated maturation temperature or shortened maturation period.


2004 ◽  
Vol 16 (2) ◽  
pp. 154
Author(s):  
H.S. Park ◽  
M.Y. Lee ◽  
S.P. Hong ◽  
J.I. Jin ◽  
J.K. Park ◽  
...  

Recent techniques in somatic cell nuclear transfer (SCNT) have been widely used for animal research. In addition, SCNT techniques may allow for the rescue of endangered species. Despite efforts for wildlife preservation, however, some threatened or endangered wild animal species will likely become extinct. As a preliminary experiment of a series in wildlife research, we tried to identify an improved method for the production of more transferable NT embryos in goats. Mature donor animals of Korean native goats (20–25kg) were synchronized with a CIDR (type G; InterAg, New Zealand) vaginal implant for 10 days followed by a total of 8 twice daily injections of 70mg of FSH (Folltropine, London, Ontario, Canada) and 400IU of hCG (Chorulon, Intervet, Moxmeer, The Netherlands). Oocytes were then collected surgically by retograde oviduct flush or direct aspiration from ovarian follicles in vivo at 29–34h after hCG. Oocytes collected from follicles were matured in TCM-199 containing 10% FBS and hormones. Prepared ear skin cells from the goat were cultured in TCM-199 containing 10% FBS at 39°C, 5% CO2 in air, and confluent monolayers were obtained. Oocytes were enucleated and donor cells from serum starvation (0.5%) culture were fused through a single electric pulse (DC 2.36kvcm−1, 17μs), and then activated by a single electric pulse (AC 5vmm−1, 5s+DC 1.56kvcm−1, 30μs) or chemical treatment (5μgmL−1 ionomycin 5min−1, 1.9mM 6-DMAP/4h). Reconstructed oocytes were cultured in M16 medium with 10% goat serum (GS) for 6–7 days. Data were analyzed by chi-square test. In in vitro development, significantly (P&lt;0.05) more oocytes were cleaved (24/30, 80.0%) and developed (7/24, 29.2%) to morula or blastocyst stage, respectively, in NT oocytes activated by Iono + DMAP compared to electric stimulated oocytes (2/21, 40.0%; 0/2, 0%). There was a significant difference in in vitro development of NT embryos by the method of oocyte collection. Cleavage rate was higher (P&lt;0.05) in NT embryos from in vivo oocytes (23/28, 82.1%) than in in vitro matured oocytes (19/35, 54.3%), and further development to morula or blastocyst was also significantly (P&lt;0.05%) higher in NT embryos from in vivo oocytes (7/23, 30.4%) than in NT embryos from in vitro matured oocytes (0/19, 0%). When we compared NT embryos to parthenotes, developmental rate was not significantly different between NT embryos and parthenotes. These results strongly suggest that the in vivo oocytes will have superior developmental potential to oocytes matured in vitro. Table 1 Effect of different oocyte source on in vitro development following caprine SCNT


2013 ◽  
Vol 25 (1) ◽  
pp. 219
Author(s):  
J. H. Moon ◽  
S. J. Kim ◽  
J. T. Kang ◽  
S. J. Park ◽  
J. Y. Choi ◽  
...  

Seminal plasma consisting of carbohydrates, proteins, and lipids not only serves as a nutritive and protective medium for sperm cells but also play a pivotal role in inducing the tolerance to pre-existing immune cells as well as improving the intra-uterine conditions for implantation of fertilized embryos (Guerin et al. 2009 Hum. Reprod. Update 15, 517–535). However, the effects of seminal plasma in in vitro culture of fertilized embryos are unknown. In the present study, the seminal plasma was separated from the second fraction of a normal farm boar (n = 1) by centrifugation and filtered seminal plasma was stored at –30°C until use. In a preliminary experiment, the optimal activity of seminal plasma was evaluated by incubating the embryos for different time intervals. To investigate the developmental rates, electrically (EA) (triplicates, n = 490) or chemically (CA) (quintuplicates, n = 599) activated 2-day-old porcine embryos were incubated for 3 h in PZM-5 medium (Funakoshi Co., Tokyo, Japan, Catalog no. IFP0410P) containing 0% (EA: n = 122 and CA: n = 152), 0.1% (EA: n = 123 and CA: n = 148), 0.5% (EA: n = 122 and CA: n = 150), or 1% (EA: n = 123 and CA: n = 149) seminal plasma. Similarly, the developmental rate of chemically activated 2-day-old somatic cell nuclear transferred porcine embryos (quadruplicates, n = 239) was studied after incubation with 0% (n = 119) or 0.1% (n = 120) seminal plasma for 3 h. A significant difference was noticed only in the rate of blastocyst formation in the chemically activated embryos treated with 0.1% seminal plasma (31.7 v. 24.8% in the 0% group, ANOVA; P < 0.05; Prism5, GraphPad Software Inc., La Jolla, CA, USA). None of the treatments showed a significant effect on the cleavage rate and cell numbers of blastocysts. In conclusion, the seminal plasma did not show any harmful effect on early embryos development. Furthermore, the seminal plasma (0.1%) improved the rate of blastocyst formation among the chemically activated nuclear transferred embryos. The results of this preliminary study suggest that the addition of seminal plasma during embryo transfer could increase the rate of pregnancy in pig. This study was supported by MKE (#10033839-2012-21), IPET (#311011-05-1-SB010), the Research Institute for Veterinary Science, and TS Corporation.


2010 ◽  
Vol 58 (4) ◽  
pp. 465-474 ◽  
Author(s):  
Tamás Somfai ◽  
Yasushi Inaba ◽  
Yoshio Aikawa ◽  
Masaki Ohtake ◽  
Shuji Kobayashi ◽  
...  

The aim of the present study was to optimise the culture conditions for the in vitro production of bovine embryos. The development of in vitro fertilised bovine oocytes in CR1aa supplemented with 5% calf serum and IVD101 culture media were compared using traditional microdrops and Well of the Well (WOW) culture systems either under 5% or 20% oxygen tension. After 7 days of culture, a significantly higher blastocyst formation rate was obtained for embryos cultured in CR1aa medium compared to those cultured in IVD101, irrespective of O 2 tensions and culture systems. The blastocyst formation in IVD101 was suppressed under 20% O 2 compared to 5% O 2 . Despite their similar total cell numbers, higher rates of inner cell mass (ICM) cells were observed in blastocysts developed in IVD101 medium than in those developed in CR1aa, irrespective of O 2 tensions. There was no significant difference in blastocyst formation, total, ICM and trophectoderm (TE) cell numbers between embryos obtained by microdrop and WOW culture systems irrespective of the culture media and O 2 tensions used. In conclusion, CR1aa resulted in higher blastocyst formation rates irrespective of O 2 tension, whereas IVD101 supported blastocyst formation only under low O 2 levels but enhanced the proliferation of ICM cells.


2008 ◽  
Vol 20 (1) ◽  
pp. 109 ◽  
Author(s):  
B. S. Song ◽  
J. S. Kim ◽  
X. L. Jin ◽  
Y. Y. Lee ◽  
Y. J. Cho ◽  
...  

Interspecies somatic cell nuclear transfer (iSCNT) is an invaluable tool for studying nucleus–cytoplasm interaction and it provides a possible alternative to cloning animals whose oocytes are limited. In Experiment 1 of the present study, we investigated the developmental potential of iSCNT embryos created from monkey, pig, and goat donor cells and bovine cytoplasts. Bovine ovaries were obtained at a local slaughterhouse and the cumulus-oocyte complexes (COCs) aspirated. COCs were matured in vitro in TCM-199 supplemented with 10 IU mL–1 pregnant mare serum gonadotropin (PMSG), 10 IU mL–1 hCG, and 10 ng mL–1 epidermal growth factor (EGF) at 38.5�C and 5% CO2 in air for 20–22 h. At the end of IVM, half of the COCs were inseminated using frozen semen (1 � 106 sperm mL–1) and the remainder were used for iSCNT after the cumulus cells were removed with 0.1% hyaluronidase in TCM-199. The procedure of iSCNT and establishment of donor cells were according to Koo et al. (2002 Biol. Reprod. 67, 487–492). After IVF and iSCNT, presumptive zygotes were cultured in CR1-aa medium supplement with 0.3% BSA. After 3 days, cleaved embryos were transferred to CR1-aa medium supplemented with 10% FBS and cultured for an additional 4 days. In Experiment 2, we investigated the developmental ability of reconstructed embryos produced from monkey cells and bovine cytoplasts using various IVC media, such as IVC-1/2 (InVitroCare, Frederick, MD, USA), G-1/2 (Vitrolife, Inc., Englewood, CO, USA) and complete medium (CM; Irvine Scientific, Santa Clara, CA, USA). All experiments were repeated more than three times and data were analyzed with t-test of one-way ANOVA using the SAS 8.01 program (SAS Institute, Inc., Cary, NC, USA). Cleavage and developmental rate of blastocysts were expressed as mean � SEM. In Experiment 1, we investigated the development ability among IVF, SCNT (bovine-bovine), and iSCNT (monkey-bovine, pig-bovine, and goatbovine) embryos cultured in CR1-aa medium. Our results showed that the cleavage rate of IVF (73.6 � 1.8%, 86/117) embryos was not significantly different compared to SCNT (84.6 � 2.7%, 38/45), and iSCNT (89.3 � 2.7%, 100/110, monkey; 89.3 � 3.3%, 45/49, pig; and 86.0 � 2.3%, 87/95, goat). Although cloned embryos reconstructed with monkey cells did not develop to the blastocyst stage, iSCNT embryos derived from pig and goat cells did (3.3 � 3.0%, 2/49, and 7.9 � 1.7%, 7/95, respectively). However, these blastocyst formation rates were significantly lower compared to those of IVF and SCNT bovine embryos (32.5 � 2.9%, 38/117, and 26.7 � 2.8%, 12/88, respectively; P < 0.05). The success of iSCNT was confirmed by PCR of mitochondrial DNA, porcine PKA region, and SRY region. In Experiment 2, we investigated the developmental potential of cloned embryos produced by monkey cells using various IVC media (IVC-1/2, G-1/2, and CM). The cleavage rate of iSCNT embryos was not significantly different among these media (86.9 � 2.7%, 78.1 � 2.1%, and 82.3 � 1.8%, respectively). However, we did not observe blastocyst formation using these media. Therefore, we suggest that the cytoplasts of bovine oocytes can support blastocyst development of cloned embryos with pig and goat cells, but they were not suitable for monkey cells. In conclusion, our results suggest that species-specific differences are apparent in the production of iSCNT embryos.


2008 ◽  
Vol 20 (1) ◽  
pp. 145
Author(s):  
H. J. Kim ◽  
S. R. Cho ◽  
C. Y. Choe ◽  
S. H. Choi ◽  
D. S. Son ◽  
...  

The objective of this study was to examine the selection effects of in vitro matured porcine follicular oocytes with polar body extrusion and early cleavage as a non-invasive marker to know the developmental competence in advance. Porcine oocytes matured for 48 h and then examined for polar body extrusion. The examined oocytes were matured for an additional 16–18 h, activated with 7% ethanol, and cultured in 5 µg mL–1 cytochalasin B for 5 h for diploid formation. The treated oocytes were examined for cleavage after 48 h and continued culturing for 5 days. Each treatment was replicated by 3–4 times. Oocytes of 21.9% (70/320) were discarded in morphological selection, and 32.1% (167/520) oocytes were discarded by failure of first polar body extrusion. The selected oocytes were matured and activated, and after 48 h, the cleavage rate was examined. In morphologically selected oocytes, 15.8% (30/190) were not cleaved, 52.6% (100/190) were normally cleaved (consisted of 2–7 cells), and 31.6% (60/190) were hyper-cleaved (consisted of 8 cells or more) at 48 h after activation. However, in the first polar body extruded oocytes, 7.1% (18/253) were not cleaved, 73.1% (185/253) were normally cleaved, and 19.8% (50/253) were hyper-cleaved. From the morphologically selected oocytes, 16.7% (10/60) were developed up to blastocyst stage from those in which cleavage selection was not performed and 31.7% (19/60) from those in which cleavage selection was performed. From the polar body extruded oocytes, 39.0% (39/100) were developed up to blastocyst stage from those in which cleavage selection was not performed and 49.0% (49/100) from those in which cleavage selection was performed. Cleavage was examined within 12 h interval after activation (0 = time of activation) up to 48 h. At 0–12, 12–24, 24–36, and 36–48 h intervals, 4.1% (9/220), 68.6% (151/220), 19.1% (42/220), and 2.3% (5/220) oocytes were cleaved, respectively, and 5.9% (13/220) oocytes were not cleaved at 48 h after activation. The cleaved embryos in each interval were cultured and developed up to blastocyst with 0 (0/9), 39.1 (59/151), 9.5 (4/42), and 0% (0/5), respectively. This result suggests that the polar body extruded and cleaved at 12–36 h embryo has higher developmental potential than the others.


2010 ◽  
Vol 22 (1) ◽  
pp. 199
Author(s):  
L.-Y. Sung ◽  
C.-H. Chen ◽  
T.-A. Lin ◽  
L.-J. Sung ◽  
H.-Y. Su ◽  
...  

This study was designed to examine the effect of rabbit oocytes collected from oviducts v. follicles on the developmental potential of nuclear transplant (NT) embryos. Rabbit oocytes were flushed from the oviducts (oviduct oocytes) or collected from the ovarian Graafian follicles(follicular oocytes) of superovulated does at 12 h post-hCG injection (hpi). Cumulus cells were then removed from the oocytes by incubation in 0.5% hyaluronidase and pipetting. Oocyte enucleation was conducted in TCM-199 +10% fetal bovine serum (FBS) and confirmed under fluorescent microscopy. Skin fibroblasts from an adult rabbit were prepared and cultured to passage 8 to 10 before use as nuclear donors. A donor cell with a diameter of approximately 15 to 19 μm was transferred into the perivitelline space of an enucleated oocyte and subsequently fused with the recipient oocyte by applying 3 direct current pulses at 3.2 kV cm-1 for 20 μs per pulse. Fused oocytes were activated by the same electrical stimulation described above, and then cultured in TCM-199 + 10% FBS containing 2.0 mM 6-DMAP and 5 μg mL-1 cycloheximide for 1 h. Cloned embryos were cultured in 2.5% FBS B2 medium in 5% CO2 and 95% humidified air at 38.5°C for 3 d. Embryo development to cleavage (2- to 4-cell), 8-cell, and morula/blastocyst (Mor/BL) stages was evaluated. The data were analyzed by the General Linear Model procedure (SPSS 11.0, SPSS Inc., Chicago, IL, USA).The total number of oocytes collected per animal was 27.6 ± 1.3, with 47.8% from oviducts, and 52.2% from follicles. The percentage of oviduct oocytes that showed the first polar body was 98.3% (n = 150) at the time of collection, whereas follicular oocytes only had 54.8% at collection (n = 93), but it reached 92.4% when immature follicular oocytes were cultured for 3 h in vitro. The enucleation rates were similar between the follicular (82.7%) and the oviduct (79.1%) groups. Table 1 shows that a significantly higher fusion rate was found in follicular oocytes compared with that in the oviduct group (90.8 v. 63.4%; P < 0.05). There was no difference in the cleavage rate and Mor/BL development between the 2 groups, although the 8-cell(78.4 v. 63.9%; P = 0.11) and the overall efficiencies (30.6% v. 17.9%; P = 0.14) appeared higher in the follicular group. These results demonstrated that rabbit follicular oocytes at 12 hpi have potential equivalent or maybe better (fusion) than that with oviduct oocytes for promoting the preimplantational development of NT embryos. Table 1.The effect of follicular and oviduct oocytes on the development of rabbit NT embryos Supported by NIH1R43 RR023774-01A1 and 5R44HL091605-03.


2009 ◽  
Vol 21 (1) ◽  
pp. 166
Author(s):  
Y. H. Zhang ◽  
H. T. Xi ◽  
Y. Liu ◽  
J. Li ◽  
A. Pederson ◽  
...  

The present study was designed to examine if frozen storage of porcine zygote medium (PZM3) plus 3 mg mL–1 BSA (Yoshioka et al. 2002 Bio. Reprod. 66, 112–119) is feasible to culture pig embryos produced by parthenogenetic activation and somatic nuclear transfer. Slaughterhouse-derived sow cumulus–oocyte complexes (COCs) were matured in TCM199 supplemented with 10% porcine follicle fluid, 5% cattle serum, 10 IU mL–1 eCG, 5 IU mL–1 hCG, 0.8 mm L-glutamine and 0.05 mg mL–1 gentamicin at 38.5°C, 100% humidity and 5% CO2 in air. For activation, cumulus cells were removed after 42 to 44 h of maturation, and the denuded oocytes with 1st polar body were activated with a double 160 V mm–1, 100 μs direct pulse followed by culture in PZM3. Each experiment was replicated at least three times. Data were expressed as mean ± SEM and analyzed by using chi-square module in SPSS 11.0, with P < 0.05 denoting significant difference. In Experiment 1, after preparation, liquid PZM3 was aliquoted to 50 mL falcon centrifuge tubes. Randomly, half of the tubes with PZM3 were put into –80°C freezers, and the rest were placed into 4°C refrigerator. Within one week after storage, a tube of frozen PZM3, while that stored at 4°C served as control, was warmed at 38.5°C in CO2 incubator, and more than three 4-well culture dishes were then made with 400 μL PZM3 in each well and balanced for at least 4 h in the incubator before experiment. The results showed that both cleavage (78/93, 83.9 ± 1.2% v. 87/103, 84.5 ± 1.8%, P > 0.05) and blastocyst (60/93, 65.2 ± 2.1% v. 65/103, 63.1 ± 3.8%, P > 0.05) rates were similar between frozen-warmed PZM3 and control, as was total cell numbers per blastocyst (50 ± 7 v. 47 ± 5, P > 0.05) between groups. In Experiment 2, we used somatic cloned embryos to investigate the effect of frozen-warmed PZM3 on pre-implantation development of such embryos. Our results indicated that no significant difference in rates of cleavage (68/95, 71.5 ± 5.1% v. 78/100, 78.1 ± 1.9%, P > 0.05), blastocyst formation (33/95, 34.6 ± 7.6% v. 78/100, 38.2 ± 3.5%, P > 0.05) and total cell numbers per blastocyst (40 ± 11 v. 48 ± 9, P > 0.05) was found between the test and control groups, designed the same as in Experiment 1. In Experiment 3, we tested whether PZM3 in frozen storage for 5 months was able to support in vitro development of parthenotes comparable to freshly-made ones. PZM3 after frozen storage for 5 months was warmed using the same method as Experiment 1, and the newly made PZM3 within 1 week of storage at 4°C acted as control. The results showed that although the cleavage (135/138, 97.8 ± 2.7% v. 117/129, 90.7 ± 3.1%, P > 0.05) and blastocyst (104/138, 75.4 ± 1.6% v. 84/129, 65.1 ± 2.3, P > 0.05) rates in control group were both slightly higher than that in the test group, no statistical differences was observed. We also found no significant difference in total cell numbers per blastocyst (48 ± 7 v. 46 ± 6, P > 0.05) between groups. Taken together, our results imply that frozen storage of PZM3 is feasible, and of practical value for culture pig embryos.


2011 ◽  
Vol 23 (1) ◽  
pp. 170 ◽  
Author(s):  
K. C. Lehloenya ◽  
N. Mahoete ◽  
J. P. C. Greyling ◽  
T. L. Nedambale

Ovine embryonic development was evaluated 8 days following in vitro fertilization, after using fresh or frozen–thawed Merino and indigenous (Pedi and Zulu) sheep semen. Semen used was collected twice weekly over a 3-month period with the aid of an electro-ejaculator. Following collection, semen samples were evaluated and semen with acceptable sperm motility and a percentage live sperm of 60% diluted with an egg yolk-based extender (Egg-Yolk Citrate). Semen samples were cryopreserved in straws with a programmable freezer to –130°C and then plunged into liquid nitrogen (–196°C) until used for IVF. Fresh and frozen–thawed semen was used to fertilize the matured oocytes in vitro. A total of 791 oocytes were fertilized using fresh semen and 802 oocytes fertilized using frozen–thawed semen. No significant differences were recorded between the fresh and frozen–thawed semen regarding the embryonic developmental stages. The performance of fresh and frozen–thawed semen followed the same trend, with the cleavage rate gradually declining with the progression in time and the embryonic developmental stage. The lowest developmental rate recorded was the occurrence of blastocyst formation, ranging between 0.4 ± 0.4% and 2.6 ± 1.0%. Regarding breed, no significant difference was observed from cleavage to the 2- to 4-cell stages. The use of fresh and frozen–thawed Zulu semen resulted in a significantly (P < 0.05) higher percentage of 8-cell development compared with the Pedi semen. However, the 8-cell embryonic stage recorded with the use of the Zulu ram semen (fresh and frozen–thawed), did not differ significantly from that of the Merino breed. No significant difference between the breeds regarding blastocyst formation was recorded. The overall cleavage rate, 2- to 4-cell, and blastocyst embryonic developmental stages following the use of fresh and frozen–thawed semen from the different rams were generally lower than those recorded by other researchers. The low blastocyst rates obtained warrant more research regarding the in vitro embryo production technique in order to improve the ovine blastocyst formation rate. The study was funded by the University of the Free State and conducted at the Germplasm Conservation and Reproduction Biotechnologies ARC.


2007 ◽  
Vol 19 (1) ◽  
pp. 293 ◽  
Author(s):  
K. Song ◽  
J. Park ◽  
E. Lee

Oocytes for somatic cell nuclear transfer (SCNT) have to be removed from their cumulus cells before enucleation. Denuding oocytes by vortexing or repeated pipetting makes the polar body (PB) deviate from the metaphase (MII) plate, which in turn makes it difficult to remove DNA materials completely during enucleation. We hypothesized that denuding oocytes at 30 h of IVM maintains the MII plate and PB in a closer position and therefore makes it easy to enucleate. To test this hypothesis, oocytes were matured in TCM-199 supplemented follicular fluid, hormones, EGF, cysteine, and insulin for first 22 h, and in a hormone-free medium for 18 h with three modifications: (1) cumulus cells were removed from oocytes just prior to enucleation at 40 h of IVM (control), (2) oocytes were denuded at 30 h of IVM and co-cultured with their detached cumulus cells for 10 h (D+), and (3) oocytes denuded at 30 h of IVM were cultured without cumulus cells (D-). After IVM, some oocytes were stained with Hoechst 33342 and photographed by a digital camera; the distance between the MII plate and the PB were measured using an image analysis program (ImageJ 1.36; http://rsb.info.nih.gov/ij). Also, the enucleation rate after blind enucleation and the in vitro development of SCNT embryos were determined. For SCNT, oocytes were enucleated, and nuclear material from donor cells (skin fibroblasts from a miniature pig) was inserted; oocytes were then electrically fused, and activated 1 h after fusion. SCNT embryos were cultured in a modified NCSU-23 (Park et al. 2005 Zygote 13, 269-275) for 6 days. Embryos were examined for their cleavage and blastocyst formation on Days 2 and 6, respectively (the day of SCNT was designated Day 0). Data were analyzed by the GLM procedure and the least significant difference test in SAS (SAS Institute, Cary, NC, USA). The distance between the MII plate and the PB was significantly (P &lt; 0.01) shorter in D+ and D- embryos (19.4 and 18.9 �m, respectively) than in the controls (25.5 �m). Enucleation rates after blind enucleation were significantly (P &lt; 0.01) higher in D+ and D- groups (77% and 72%, respectively) than in the controls (60%). Oocyte maturation (89–91%), SCNT embryo cleavage (71–77%), blastocyst formation (4–5%), and embryo cell number (39-45 cells/embryo) were not altered by different denuding methods. The perivitelline space (PVS) increases with time during maturation and denudation, after PB extrusion markedly enhances PB deviation. It is likely that increased PVS in control oocytes enhanced PB deviation during denudation and then resulted in lower enucleation rate. In conclusion, the results of this study indicated that denuding at 30 h of IVM maintained the MII plate and the PB in a closer position and improved enucleation efficiency without impairing developmental capacity of SCNT embryos. This work was supported by the Research Project on the Production of Bio-organs (No. 200506020601), Ministry of Agriculture and Forestry, Republic of Korea.


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