• Journal of Embryo Transfer
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• v.13 no.1
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• pp.11-19
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• 1998

This study was to determine the effect of ionomycin and 6-dimethylaminopurine (6-DMAP) and/or elcetrical stimulation on the oocyte activation and production of rabbit nuclear transplant embryos. The oocytes were collected from the oviduct of superovulated rabbits at 14 h post hCG injection and cultured in TCM-199 containing 10% FBS until 19 h post hCG injection. To determine the optimum concentration and exposure time of 6-DMAP, some oocytes were activated with 5 $\mu$M ionomycin for 5 min and then in 2.0 mM 6-DMAP for 0.5 to 3.0 h, or in 1.0 to 3.0 mM 6-DMAP for 2.0 h. Other control oocytes were stimulated electrically(3X, 1.25 kV/cm, 60 $\mu$sec) in 0.3 M mannitol solution supplemented with 100 $\mu$M CaCl$_2$ and MgCl$_2$. The nuclear donor embryos of 8-cell stage were synchronized to G$_1$ phase of 16-cell stage, and the recipient cytoplasms were obtained from removal of the first polar body and a portion of membrane bound cytoplasm of the oocytes collected at 15 h post hCG injection. A separated blastomere was injected into the perivitelline space of the enucleated oocytes. The oocytes injected with nucleus were cultured until 19 h post hCG and then electrofused and activated by electrical stimulation with or without ionomycin and 6-DMAP. These nuclear transplant embryos were cultured in TCM-199 containing 10% FBS in 39˚C, 5% CO2 incubator for 120 h. For the oncytes activated parthenogenetically with electrical stimulation with or with-out ionomycin and the various concentration of exposure time of 6-DMAP, the highest cleavage(92.3%) and development to blastocyst stage(41.0%) were resulted from the oocytes activated by ionomycin and 2.0 mM 6-DMAP for 2.0 h, which were found to be significantly(P<0.05) higher than the cleavage(45.2%) and developement to blastocyst stage(14.3%) from the oocytes activated with electrical stimulation. The significantly(P<0.05) more oocytes(71.4%) developed to 4 cell stage at 24 h post activation by ionomycin and 6-DMAP than those by electrical stimulation(18.9%). For the nuclear transplant embryos, the cleavage rate was similarly high in oocyte activation by electrical stimulation with(79.4%) or without ionomycin and 6-DMAP(70.5%). However, the embryo development to blastocyst stage was significantly(P<0.05) higher in oocyte activation by electrical stimulation with ionomycin and 6-DMAP(44.4%) than by electrical stimulation only(25.0%). The significantly(P<0.05) more nuclear transplant embryos(45.6%) developed to 4 cell stage at 18 h post activation by electrical stimulation with ionomycin and 6-DMAP than those by electrical stimulation only(10.6%). These results indicated that the supplemental oocyte activation by ionomycin and 6-DMAP with electrical stimulation enhanced and accelerated the preimplanted in vitro development of the rabbit nuclear transplant embryos.

• Clinical and Experimental Reproductive Medicine
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• v.43 no.2
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• pp.119-125
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• 2016

Objective: The aim of this study was to report a case series of in vitro matured (IVM) oocyte freezing in gynecologic cancer patients undergoing radical surgery under time constraints as an option for fertility preservation (FP). Methods: Case series report. University-based in vitro fertilization center. Six gynecologic cancer patients who were scheduled to undergo radical surgery the next day were referred for FP. The patients had endometrial (n=2), ovarian (n=3), and double primary endometrial and ovarian (n=1) cancer. Ex vivo retrieval of immature oocytes from macroscopically normal ovarian tissue was followed by mature oocyte freezing after IVM or embryo freezing with intracytoplasmic sperm injection. Results: A total of 53 oocytes were retrieved from five patients, with a mean of 10.6 oocytes per patient. After IVM, a total of 36 mature oocytes were obtained, demonstrating a 67.9% maturation rate. With regard to the ovarian cancer patients, seven IVM oocytes were frozen from patient 3, who had stage IC cancer, whereas one IVM oocyte was frozen from patient 4, who had stage IV cancer despite being of a similar age. With regard to the endometrial cancer patients, 15 IVM oocytes from patient 1 were frozen. Five embryos were frozen after the fertilization of IVM oocytes from patient 6. Conclusion: Immature oocytes can be successfully retrieved ex vivo from macroscopically normal ovarian tissue before radical surgery. IVM oocyte freezing provides a possible FP option in patients with advanced-stage endometrial or ovarian cancer without the risk of cancer cell spillage or time delays.

• Clinical and Experimental Reproductive Medicine
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• v.30 no.4
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• pp.333-340
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• 2003

Objective: This study was performed to examine the maturation and the development to the blastocyst stage of immature oocytes collected from patients with high risk of ovarian hyperstimulation syndrome (OHSS). Materials and Methods: Cumulus-oocyte complexes (COCs) were collected following only HCGpriming for non stimulated IVF-ET cycles of the patients. At the time of oocyte collection, COCs were classified into three groups in accordance with their appearance (Group I: oocytes with dispersed cumulus cells; Group II: oocytes with compacted cumulus cells; Group III: oocytes with sparse cumulus cells). The in vitro maturation and blastocyst development rates of the COCs were compared among these groups. From August 2001 to June 2002, 48 IVM/IVF-ET cycles from 42 patients (mean age: $32.4{\pm}3.8$ years) were performed. To prevent the occurrence of OHSS, the patients were primed with 10, 000 IU HCG alone 36 h before oocyte collection without gonadotropin stimulation. Oocytes were aspirated on cycle days from 7 to 13. The normal COCs were classified into three groups according to their appearance. The aspirated immature oocytes were cultured in YS maturation medium containing 30% (v/v) human follicular fluid (HFF), 1 IU/ml FSH, 10 IU/ml HCG and 10 ng/ml rhEGF. Fertilization was induced by intracytoplasmic sperm injection (ICSI). All zygotes were co-cultured with cumulus cells in $10{\mu}l$ YS medium containing 10% HFF until day 7 after oocyte collection. Blastocyst transfer was performed on day 5 after ICSI. Results: Th e mean number of oocytes cultured in the IVM/IVF cycles was $24.7{\pm}10.6$. Of 1185 COCs, those assigned to Group I, II and III were 470 (39.7%), 414 (35.0%) and 301 (25.4%), respectively. The maturation rate (94.5%, 444/470, p<0.05) in Group I was significantly higher than those of Group II (62.8%, 260/414) and Group III (73.1%, 220/301). Especially, 30.9% of COCs in Group I (145/470) was matured on the day of oocyte aspiration. There were no differences in the rates of fertilization and cleavage among the three groups. The development rate to the blastocyst stage in Group I (54.6%, 206/377, p<0.05) was also significantly higher than those in Group II (33.0%, 68/206) and Group III (30.1%, 52/173). Twenty-four clinical pregnancies (50.0%) was obtained and 22 pregnancies (45.8%) are ongoing. Implantation rate in the present study was 24.6%. Conclusion: These results suggest that there is a positive correlation between the appearance of COCs and the developmental competence of the immature oocytes in non stimulated IVM/IVF cycles.

• The Korean Journal of Zoology
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• v.33 no.2
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• pp.175-182
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• 1990

Progesterone production and oocyte maturation in ovarian follicles of Rana nigromaculata and Rana rugosa were investigated. Addition of frog pituitary homogenate (FPH) to the in utiro cultured follicles of R. nigromaculata stimulated a marked increase in the accumulation and secretion of progesterone (P$_4$) by the follicles and induced their oocyte maturation (germinal vesicle breakdown, GVBD) in a dose dependent manner. The FPH (0.1 pituitary equivalent/2 ml)-inducted P4 peak appeared in 3-6 hours and followed by the oocyte GVBD in 9-12 hours after the hormone stimulation. lncreae of intrafollicular cAMP levels with forskolin (an adenylatecyclase stimulator) and 3-isobutyl-1-methylxanthine (IBMX, a phosphodiesterase inhibitor) mimic the FPH action in the stimulation of P$_4$ production but not in the induction of oocyte maturation. The in uitro cultured follicies of R. rugosa behaved very differently from other amphibian follicles. Addition of FPH-(0. 1 pit. equivl2 ml) to the culture medium neither stimulated P$_4$ production by the follicles nor induced the oocyte GVBD. However, treatment of the follicles with forskolin and IBMX drastically stimulated both the intrafollicular accumulation (800 pg/follicle) and secretion (1700 pg/follicle) of P$_4$ by the follicles during culture period. Thus, the data suggest that the follicles are ready to respond to cAMP increase but not to the FPH stimulation in terms of P$_4$ production.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.139-146
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• 2017

The objective of this study was to determine the effect of fructose that was supplemented to a chemically defined in vitro maturation (IVM) medium on oocyte maturation and embryonic development after parthenogenesis in pigs. The base medium for in vitro maturation (IVM) was porcine zygote medium (PZM) that was supplemented with 0.05% (w/v) polyvinyl alcohol (PVA) or 10% (v/v) porcine follicular fluid (pFF). In the first experiment, when immature pig oocytes were matured in a chemically defined medium that was supplemented with 5.5 mM glucose or with 1.5, 3.0 and 5.5 mM fructose, 3.0 mM fructose resulted in a higher nuclear maturation (91.5%) than 1.5 and 5.5 mM fructose (81.9 and 81.9%, respectively) but showed a similar result with 5.5 mM glucose (94.2%). However, there was no significant differences among groups in the embryo cleavage (89.4-92.4%), blastocyst formation (37.5-41.1%), and mean cell number of blastocyst (30.8-34.2 cells). Fructose at the concentration of 3.0 mM (1.08 pixels/oocyte) resulted in a higher intra-oocyte glutathione (GSH) content than 1.5 and 5.5 mM fructose (1.00 and 0.87 pixels/oocytes, respectively) while the cumulus cell expansion was not influenced. In the second experiment, effect of individual and combined supplementation of a chemically defined maturation medium with 5.5 mM glucose or 3.0 mM fructose was examined. No significant effect was found in the nuclear maturation (86.3-92.6%). Embryo cleavage was significantly increased by the combined supplementation with glucose and fructose (95.2%) compared to that with 3.0 mM fructose only (85.7%) while blastocyst formation (37.3-42.8%) and embryonic cell number (33.3-34.1 cells) were not altered. Effect of supplementation of pFF-containing medium with glucose and fructose + glucose was examined in the third experiment. No significant effect by the supplementation with glucose and fructose or glucose alone was observed in the nuclear maturation of oocytes (90.7-94.1%) and blastocyst formation (51.0-56.5%). Our results demonstrate that 3.0 mM fructose was comparable to 5.5 mM glucose in supporting in vitro oocyte maturation and embryonic development after parthenogenesis and could be used as an alternative energy source to glucose for in vitro maturation of pig oocytes.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.7
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• pp.956-965
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• 2019

Objective: The main goal of this study was to provide a morphological indicator that could be used to select high-quality oocytes of appropriate meiotic and developmental capabilities in pig. The higher quality of immature oocytes, the higher success rates of in vitro maturation (IVM) and in vitro fertilization (IVF). Thus, prior to the IVM culture, it is important to characterize oocytes morphologically and biochemically in order to assess their quality. Two of the largest indicators of oocyte quality are the presence of cumulus cells and status of chromatin. To investigate the effects of porcine oocyte chromatin configurations on the developmental capacity of blastocysts, we assessed oocyte chromatin status according to follicle size and measured the developmental potency of blastocysts. Methods: To sort by follicle size, we divided the oocytes into three groups (less than 1 mm, 1 to 3 mm, and more than 3 mm in diameter). To assess chromatin configuration, the oocytes were assessed for their stages (surrounded nucleolus [SN] germinal vesicle [GV], non-surrounded nucleolus [NSN] GV, GV breakdown, metaphase I [MI], pro-metaphase II [proMII], and metaphase II [MII]) at different maturation times (22, 44, and 66 h). To assess the development rate, oocytes of each follicle size were subjected to parthenogenetic activation for further development. Finally, GV oocytes were grouped by their chromatin configuration (SN, SN/NSN, and NSN) and their global transcriptional levels were measured. Results: SN GV oocytes were more suitable for IVF than NSN GV oocytes. Moreover, oocytes collected from the larger follicles had a greater distribution of SN GV oocytes and a higher developmental capacity during IVM, reaching MII more quickly and developing more often to blastocysts. Conclusion: Porcine oocytes with high-level meiotic and developmental capacity were identified by analyzing the relationship between follicle size and chromatin configuration. The porcine oocytes from large follicles had a significantly higher SN status in which the transcription level was low and could be better in the degree of meiotic progression and developmental capacity.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.266-266
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• 2004

재래산양은 우리나라 고유의 재래가축이라는 특성과 산양육의 경우 건강보조식품으로서의 인식이 팽배해 왔기 때문에 그동안 체계적인 개량이 이루어지지 못하였다. 동물복제 또는 형질전환 등과 같은 첨단생명공학연구를 위해서는 무엇보다도 oocyte의 대량확보가 가능해야 한다. 본 연구는 재래산양에 있어서 과배란 처리에 의한 oocyte의 회수방법과 회수란의 질적 개선을 확립하기 위하여 과배란 처리 후 회수시간이 난포의 발달과 난자의 회수율에 미치는 영향을 조사하였다. (중략)

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.72-72
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• 2002

Oocytes maturation, characterized by germinal vesicle (GV) breakdown, formation of the first meiotic spindle, expulsion of the first polar body and arrest in metaphase of second meiotic division (MII), occurs in preovulatory follicles in response to the surge of gonadotropin and leads to an ovulated oocyte in vivo. However, meiotic resumption in vitro occurs spontaneously following removal of cumulus-oocytes complexes (COCs) from the follicle. (omitted)

• 대한생식의학회:학술대회논문집
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• 1999.11a
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• pp.83.1-83.1
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• 1999

• The Korean Journal of Zoology
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• v.39 no.2
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• pp.198-206
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• 1996

Adhesive membranes in the oocvtes of four loach fishes of Korea were investigated by light and electron microscopes to clarify the structural characteristics among the species. In the vitellosenic stage the adhesive membranes of oocvtes could be classified into two forms as follows: 1) fence-shaped form of Nemacheilus yoni and 2) non-adhesive membranous form of Misgurnus anguillicoudotus, M. Mizolepis, and Lefuo costuto. The adhesive membranes of oocvtes in the loach fishes showed a species specificity with reference to their habitats and spawning properties.