• Journal of Embryo Transfer
• /
• v.21 no.3
• /
• pp.183-190
• /
• 2006

These studies were conducted to monitor developmental competence of follicular oocytes collected from the carcass of the high meat quality in Korean native cattle using each individual protocol of IVM, IVF and IVC. The follicular oocytes that were collected from the ovaries of the cow yielded 1, $1^+\;and\;1^{++}$ meat quality were matured, fertilized and cultured using each individual protocol of IVM, IVF and IVC. As results, the number of follicular oocytes collected from individual fundamentally-registered cows yielded 1, $1^+\;and\;1^{++}$ meat grade were 28.9, 28.8 and 29.6 per head, respectively. The rates of blastocyst formation after IVM, IVF and IVC were 27.2, 28.7 and 32.9% in the cows yielded 1, $1^+\;and\;1^{++}$ meat quality, respectively. The rate of blastocyst formation was 8.4 per head. The number of follicular oocytes collected from pedigree registered cows yielded 1, $1^+\;and\;1^{++}$ meat quality were 25.8, 27.1 and 27.0 per head, respectively. The rates of blastocyst formation were 23.0, 33.7 and 42.6% in the meat quality of 1, $1^+\;and\;1^{++}$ after in vitro-manipulation, respectively (p<0.05). The rate of blastocyst formation was 8.5 per head. In conclusion, these results suggest that in vitro embryo production system using individual culture system including IVM, IVF and IVC can make good use of the gene from the carcass of the high meat quality in Korean native cattle.

• Korean Journal of Animal Reproduction
• /
• v.17 no.1
• /
• pp.57-68
• /
• 1993

This stduy was carried out to find a reliable method for the production of in vitro fertilized embryos having more excellent development capacity and freezability in the rabbit and cattle. The greatest number of rabbit oocytes was recovered 6hrs after HCG injection(P<0.05). The maturation rate in vitro was slightly higher in the oocytes(6-h-oocytes) from 6h than those (8-h-oocytes)from 8 hrs after HCG injection and the beneficial effect of FSH during oocyte maturation was significantly great in the oocytes from large follicles. The cleavage rate into 2-to-6-cell stage was not differ between the 6-h-oocytes and 8h-oocytes, but the cleavage of these oocytes was greatly promoted by FSH addition to maturation medium and the cleavge of 8-h-oocytes matured without FSH was significantly low. The embryo development into 16-cell to morula was not promoted by the co-culture with rabbit oviduct epithelial cells. The freezability by embryo stages was ovidusly high at 4-cell and morula stage in 6-h-oocytes and the viability of 16-cell embryos from 8h-oocytes was similar to that of morula stage. The implantation sites after surgical tranfer of fresh rabbit embryos were not implanted. In bovine experiment, the in vitro development into 16-cell and morula after in vitro maturation and fertilization in the follicular oocytes was slightly improved by the co-culture with granulosa cells compared to that with oviduct epithelial cells and the frozen-thawed viability rate of these embryos ranged from 14 to 40%. The excellent fresh embryos were transferred nonsurgically to 6 recipients, but were not pregnant.

• Korean Journal of Animal Reproduction
• /
• v.20 no.2
• /
• pp.179-190
• /
• 1996

Sexing and developing from splitted embryos which were fertilized in vitro implicate a possibility of production of the superior and sex controlled individuals. This study was carried out to investigate the production of transferable late blastocysts from in vitro fertilized embryos and to analyze sex by chromosome analysis from same embryos. In results, the ratio of cleavage and fertility of bovine follicular oocytes matured in vitro was 90% in co-cultured with granulosa cells. The competence of embryonic development from in vitro matured and fertilized bovine oocytes was 38% in co-cultured with bovine oviductal epithelial cells. To produce a lot of transferable embryos, therefore, the best conditon of culture system was co-cultured with granulosa cells for immature bovine oocytes and then co-cultured with bovine oviductal eptithelial cells for matured and fertilized oocytes. In chromosome analysis, 93% of in vitro fertilized embryos were very important aspect in chromosome preparation from bovine embryos such as duration of colcemid treatment, weakening of zona pellucida, methods of hypotonic treatment and fixation treatment.

• Asian-Australasian Journal of Animal Sciences
• /
• v.1 no.3
• /
• pp.153-156
• /
• 1988

Bovine blastocysts were obtained by in-vitro culture of embryos derived from in-vitro fertilization of oocytes matured in-vitro. These blastocysts and blastocysts from inseminated donors were bisected by a simple method (without a holding pipette) using a microblade operated by a micromanipulator. A pair of demi-embryos was transferred nonsurgically into each uterine horn of a recipient cow 6 or 8 days after estrus. Pregnancy resulted from the third transfer. Ultrasound examination done 52 days after estrus (46 days after transfer) confirmed the presence of at least one fetus in the each uterine horn. This is the first report to show the viability of bisected bovine blastocysts obtained from in-vitro culture of embryos derived from in-vitro fertilization of oocytes matured in-vitro. In addition, a simple method to bisect bovine embryos is described.

• Journal of Embryo Transfer
• /
• v.11 no.3
• /
• pp.241-248
• /
• 1996

This study was conducted to improve the production efficiency of in vitro produced (IVP) embryos in Korean Native cows. The optimal conditions and procedures for in vitro maturation(IVM), in vitro fertilization(IVF) and in vitro culture(IVC) of bovine follicular oocytes and IVP embryos were evaluated. Immature follicular oocytes were collected fiom the follicles of bovine ovaries obtained from abattoirs. The oocytes of Grade I and II for IVM were cocultured with monolayered bovine oviductal epithelial cells(BOEG) or granulosa cells in TCM-199 solution supplemented with follicle stimulating hormone, lutenizing hormone, estradiol-17$\beta$ and heat inactivated fetal calf serum at 39$^{\circ}C$ under 5% $CO_2$ in air for 14 to 24 hours. Most of the oocytes(93%) matured to metaphase II in 24 hours. The cocultured IVM oocytes were fertilized in vitro at significantly(P<0.05) higher rate with BOEC(83.8%) and with granulosa cells(84.6%) than the non-cocultured IVM oocytes(73.6%). The IVM-IVF embryos developed to morula and blastocyst at significantly(P<0.05) higher rate in coculture with BOEC(41.2%) than with granulosa cells(23.1%) or conditioned medium(23.4%).

• Journal of Animal Science and Technology
• /
• v.65 no.2
• /
• pp.324-335
• /
• 2023

Korea, located in East Asia in the northern hemisphere, is experiencing severe climate changes. Specifically, the heat stress caused by global warming is negatively affecting the dairy sector, including milk production and reproductive performance, as the major dairy cattle Holstein-Friesian is particularly susceptible to heat stress. Here, we collected artificial insemination and pregnancy data of the Holstein and the Jersey cows from a dairy farm from 2014 to 2021 and analyzed the association between the conception rate and the temperature-humidity index, calculated using the data from the closest official weather station. As the temperature-humidity index threshold increased, the conception rate gradually decreased. However, this decrease was steeper in the Holstein breed than in the Jersey one at a temperature-humidity index threshold of 75. To evaluate the effects of heat stress on the oocyte quality, we examined the nuclear and cytoplasmic maturation of Holstein (n = 158, obtained from six animals) and Jersey oocytes (n = 123, obtained from six animals), obtained by ovum pick-up. There were no differences in the nuclear maturation between the different conditions (heat stress: 40.5℃, non- heat stress: 37.5℃) or breeds, although the Holstein oocytes seemed to have a lower metaphase II development (p = 0.0521) after in vitro maturation under heat stress conditions. However, we found that the Holstein metaphase II oocytes exposed to heat stress presented more reactive oxygen species and a peripheral distribution of the mitochondria, compared to those of the Jersey cattle. Here, we show that weather information from local meteorological stations can be used to calculate the temperature-humidity index threshold at which heat stress influences the conception rate, and that the Jersey cows are more tolerant to heat stress in terms of their conception rate at a temperature-humidity index over 75. The lower fertility of the Holstein cows is likely attributed to impaired cytoplasmic maturation induced by heat stress. Thus, the Jersey cows can be a good breed for the sustainability of dairy farms for addressing climate changes in South Korea, as they are more resistant to hyperthermia.

• Proceedings of the KSAR Conference
• /
• 2003.06a
• /
• pp.51-51
• /
• 2003

Oct-4 is a maternally expressed octamer-binding protein encoded by the murine Oct-4 gene. It is present in unfertilized oocytes, but also in the inner cell mass and in primordial germ cells. In addition, Oct-4 is the first transcrition factor described that is specific for the blastocysts stage bovine embryos. The spatial and temporal expression patterns were further determined using Immunohistochemistry. With this technique Oct-4 protein expression is detected in the oocyte, in the blastocyst. After pregnancy Oct-4 expression is restricted ovary and placental tissue. Therefore Oct-4 is a transcription factor that is specifically expressed in cells participating in the pregnancy of Korean native cattle. These result suggest that Oct-4 localization and expression may contribute to the defects in the developmental normal seen in Korean native cattle.

• Journal of Animal Reproduction and Biotechnology
• /
• v.36 no.3
• /
• pp.162-167
• /
• 2021

Camel (camelus dromedarius) is a unique large mammalian species that can survive harsh environmental conditions and produce milk, meat, and wool. Camel reproduction is inferior when compared to other farm animal species such as cattle and sheep. Several trials have been reported to increase camel reproduction and production through assisted reproductive techniques (ARTs) such as in vitro fertilization and cloning. For these reasons, obtaining enough mature oocytes is a cornerstone for ARTs. This demand would be improved by the oocyte in vitro maturation (IVM) systems. In this review, the current approaches and views from different laboratories using ARTs and the IVM to produce embryos in vitro in camel species. For the last two decades, conventional IVM system was the common approach, however, recently the bi-phasic IVM system has been introduced and showed promising improvement in IVM of camel oocytes. Detailed studies are needed to understand camel meiosis and IVM to efficiently increase the production of this species.

• Proceedings of the KSAR Conference
• /
• 2001.03a
• /
• pp.18-18
• /
• 2001

Despite of importance of integrated events of nucleus and microtubule remodeling in nuclear transferred embryos with somatic cells, little information is available on this subject. In this study we configured chromatin and microtubule organization following somatic cell nuclear transfer in pre- and non-activated bovine oocytes in order to clearify nuclear remodeling process and to demonstrate centrosome inheritance during nuclear transfer. The cumulus-oocyte complexes were collected from slaughterhouse and were matured in vitro for 20 h in TCM 199 supplemented hormone. Matured bovine oocytes were enucleated by aspirating the frist polar body and metaphase chromatin using a beveled pipette. Bovine fibroblast cells were fused into enucleated oocyte by electrical stimulation. Reconstructed oocytes were activated with ionomycine and 6-dimethylaminopurin, and then cultured in CRlaa medium. The organization of nuclear and microtubules were observed using laser-scanning confocal microscopy. At 1 hour after fusion, microtubule aster was seen near the transferred nucleus in most oocytes regardless activation condition. While most of fibroblast nuclei remodeled to premature chromosome condensation (PCC) and to the two masses of chromosome in non-activated oocytes, a few number of fibloblasts went to PCC and multiple pronuclear like structures in activated oocytes. Microtubular spindle was seen around condensed chromosome. Gamma-tubulin was detected in the vicinity of condensed chromosome, suggesting this is a transient spindle. The spindle seperated nucleus into two masses of chromatin which developed to the pronuclear like structures. Two pronuclear like structures were than apposed by microtubular aster and formed one syngamy like nuclear structure at 15 h following nuclear transfer. At 17 to 18 h after fusion, two centrosomes were seen near the nucleus, which nucleates micrtubules for two cell cleavage. While 31% of reconstructed oocytes in non-activated condition developed to morulae and blastocysts, a few reconstructed oocytes in pre-activated condition developed to the blastocyst. These results suggested introduction of foreign centrosome during nuclear transfer, which appeared to give an important role for somatic cell nuclear reprogramming.

• Journal of Embryo Transfer
• /
• v.16 no.2
• /
• pp.99-106
• /
• 2001

This study was undertaken to compare the efficiency of recovery rate and development rate of follicular oocytes collected either by aspiration or by slicing method. The follicular oocytes collected by the two methods matured in TCM199 supplemented with 10% steer serum at 39$^{\circ}C$ in a humidified atmosphere of 5% $CO_2$in air. After 22 h of culture, the oocytes were inseminated with frozen-thawed semen (2$\times$10$^{6}$ sperm/ml of final concentration) prepared with Percoll-density gradient in IVF-TALP medium for 16 h. Later, sets of 15 presumptive zygotes were transferred into 50 $\mu$L, droplets of CR1aa medium. On day 4 of the culture, embryos were transferred to TCM199 until day 9. The percentages of nuclear maturation to pre-metaphase II in the oocytes collected by aspiration are significantly (P<0.05) higher than that by slicing (83% vs. 62%, respectively). The mean number of oocytes recovered by slicing per ovary is significantly (P<0.05) higher than that by aspiration (15.1 vs. 6.7, respectively). Although the rates of cleavage and development to blastocyst of oocytes collected b)\\\\`aspiration are significantly (P<0.05) higher than that by slicing, the number of transferable embryos obtained by slicing method is significantly (P<0.05) higher than that by aspiration. From the results. we may conclude that slicing method is better than aspiration method for obtaining large number of transferable embryos per ovary.