• Journal of Embryo Transfer
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• v.29 no.1
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• pp.1-5
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• 2014

Recent 2 decades, including in vitro maturation (IVM), assisted reproductive technologies (ARTs) achieved noteworthy development. However the efficiency of ARTs with in vitro matured oocytes is still lower than that with in vivo oocytes. To overcome those limitations, many researchers attempted to adapt co-culture system during IVM and consequently maturation efficiency has been increased. The beneficial effects of applying co-culture system is contemplated base on communication and interaction between various somatic cells and oocytes, achievement of paracrine factors, and spatial effects of extracellular matrix (ECM) from somatic cell surface. The understanding of co-culture system can provide some information to narrow the gap between in vitro and in vivo. Here we will review current studies about issues for understanding cu-culture system with various somatic cells to improve in vitro maturation microenvironment and provide bird view and strategies for further studies.

• Korean Journal of Animal Reproduction
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• v.21 no.4
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• pp.355-362
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• 1997

This study was undertaken in an effort to product embryos through in vitro maturation(IVM), in vitro fertilization(IVF) and in vitro culture(IVC) after cryopreservation of immature and mature porcine oocytes. The experiments were conducted to investigate IVM rate of oocytes frozen with 3 different cryoprotectants and to examine IVF and IVC of frozen-thawed oocytes. The CEI(cumulus cells expansion index) after IVM of frozen-thawed immature oocytes was higher in oocytes frozen with PG＋PEG(propylene glycol plus polyethylene glycol) than those frozen with single cryoprotectant and this index was almost 90% of unfrozen oocyte's index(2.39 vs. 2.66). The IVF rate of all frozen oocytes was very low(68% of unfrozen oocytes) and the IVF rate of frozen immature oocytes was slightly higher than that of frozen mature oocytes(39.0% vs. 34.4%), but polyspermic penetration was higher in frozen immature oocytes(21.9% vs. 19.1%). The cleavage rate after IVF of frozen-thawed oocytes was 9.3% for frozen mature oocytes and 11.3% for frozen immature oocytes and this rate was significantly lower(P<0.05) than that of control(60.7%). The development to 8-cell stage was greatly lower in frozen mature oocytes than in frozen immature oocytes. The results indicate that the use of PG plus PEG as cryoprotectant may be very effective for vitrification of porcine oocytes and the frozen-thawed immature porcine oocytes can be used fro in vitro embryo production based on IVM, IVF and IVC system.

• Journal of Embryo Transfer
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• v.33 no.3
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• pp.99-105
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• 2018

To determine the differences in the in-vitro ovum maturation process of bovine, we compared the expression of MMPs in these oocytes and cumulus cell throughout oocytes maturated. In an attempt to investigate the effect of MMP activation and inhibitors in total protein of cumulus cell and, oocytes during oocytes maturation, we examined and monitored the localization and expression of MMPs (MMP-2 and MMP-9), TIMPs (TIMP-2 and TIMP-3), as well as their expression profiles (Real-time PCR, Gelatin Zymography and ELISA). Our results that the bovine oocytes MMP-2 and MMP-9 level was significantly associated with the rate of maturity of oocytes (P<0.05). In cumulus cell, MMP-2 was highly expressed in all stages of the oocyte's maturation. The final oocytes maturation exhibited strong gelatinase activity. There was no significant correlation between cumulus cell MMP-9 and the maturation rate of oocytes. However, for the oocyte cytoplasm MMP-9 expression was significant correlation to the maturation oocytes. There was no significant correlation between cumulonimbus cells MMP-9 and oocyte maturation rates; however, for oocyte cytoplasm, MMP-9 expression was significantly correlated with mature oocyte. However, the TIMP-1 and TIMP-2 protein expression patterns are not correlated with the maturation rate of the oocyte. Our results suggest that MMP different expression pattern may regulate the morphological remodeling of oocyte's in the cumulus cell. Further, the MMP-2 expression has a strong relation with a higher maturation rate of the oocyte.

• Reproductive and Developmental Biology
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• v.32 no.2
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• pp.71-79
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• 2008

Surface-enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF MS) is one of the recently developed proteomic technologies which is based on capturing proteins and peptides by chemically modified surfaces and highly sensitive for the analysis of complex biological samples. In the present study, to gain insights into oocyte maturation and early embryo development, SELDI-TOF-MS was used to find the protein candidates that are specifically or prominently expressed in porcine oocytes at the in vitro matured metaphase II (MIIl) and germinal vesicle (GV) stages. By selected CM10 chip, 16 candidates were found to be up-regulated in GV stage oocytes compared with in MII stage oocytes, their molecular weights were 8,180 (2 candidates), 10,226 (5 candidates), 15,767 (5 candidates) and 16,770 (4 candidates) Da respectively. And the expression of 29 candidates were higher in MII than in GV stage oocytes, their molecular weight were 10,832 (3 candidates), 17,743 (8 candidates), 20,122 (3 candidates), 22,131 (3 candidates), 24,857 (7 candidates) and 33,507 (5 candidates) Da, respectively. The expression of selected 13 candidates (0.2 and 1.0 % error tolerances) were analyzed using real time RT-PCR. The proteins that differentially regulated during oocyte in vitro maturation in the pigs may be potential biomarkers of oocyte maturation and quality.

• Korean Journal of Animal Reproduction
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• v.21 no.2
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• pp.111-116
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• 1997

We determined the effects of follicular fluid fractions in the maturation medium on bovine oocyte maturation, fertilization and subsequent development, as well as on number of cells in blastocysts following culture. Follicular fluid and oocytes from bovine follicles less than 5 mm in diameter were collected from the ovaries of slaughtered cows. Follicular fluid was separated into different molecular weight fractions by untrafiltration through a membrane using a centrifuge at 500$\times$g, for 2h. For the maturation medium, follicular fluid fractions (30%, v/v), whole fluid (30%) or PVP(3mg/ml) were added to TCM 199(0.1$\mu\textrm{g}$/ml estradiol-17$\beta$, 100IU hCG). After maturation for 24h, oocytes were fertilized in vitro with bull frozen-thawed spermatozoa and cultured on a monolayer of granulosa cells for 9 days after fertilization. There were no differences in maturation rates or fertilization rates among any maturation conditions. The rates of development to >2-cell stage of the oocytes were significantly decreased when fraction of follicular fluid below 10,000 MW were added into maturation medium, compared with control and fraction above 10,000 MW(26.0% vs 40.8% to 64.0%, respectveily. p<0.01). Likewise, the rates of development to blastocysts of fertilized oocytes were significantly decreased in maturation medium containing fraction of follicular fluid (<10,000 MW). The average cell number of blastocysts derived from oocytes that matured in the fraction(>10,000 MW) of follicular fluid was 154.7$\pm$13.7. These embryos contained more cells than those matured in whole follicular fluid, or the fraction(<10, 000 MW) of follicular fluid or control(107.0$\pm$8.4, 91.8$\pm$11.8 and 95.8$\pm$6.2, respectively). In conclusion, we found that fractions of follicular fluid contained factors stimulating or inhibiting oocyte cytoplasmic matruation. These suggest that a factor(s) inducing cytoplasmic maturation of oocytes may exist in >10,000 MW fraction of follicular fluid.

• Korean Journal of Animal Reproduction
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• v.23 no.4
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• pp.323-331
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• 1999

The effects of insulin-like growth factor-I (IGF-I) and cumulus cells during in vitro maturation in porcine oocytes were examined. When follicular oocytes were cultured in medium with different concentrations of IGF-I, maturation rates were 60, 61 and 62 and 72% for 0, 15 and l0ng/$m\ell$ IGF-I. In medium with 10ng/$m\ell$ IGF-I, maturation rates were not significantly difference between oocytes with (68%) and without (52%) cumulus cells during the culture. In medium with-out IGF-I, however, the maturation rates in oocytes with cumulus cells (63%) was significantly (P＜0.05) higher than oocytes without cumulus cells (32%). On the other hand, when IGF-I was added for first 24 h period or later 24 h period of culture, maturation rates were higher in oocytes with (61 and 49%) that than without (49 and 45%) cumulus cells. In experiment used medium without fetal calf serum (FCS) and porcine follicular fluid (PFF), the maturation rates in oocytes with cumulus cells for 48 h (48 and 67%) or first 24 h (46 and 63%) period after culture were significantly (P＜0.01) higher than in oocytes without cumulus cells (16 and 18%) in the presence or absence of IGF-I. These results indicated that cumulus cells is essential on maturation in vitro in porcine oocytes, but IGF-I can promote oocytes maturation of oocytes without cumulus cells in medium with FCS and PFF.

• Development and Reproduction
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• v.17 no.1
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• pp.63-72
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• 2013

A specific inhibitor of RNA polymerase II, ${\alpha}$-amanitin is broadly used to block transcriptional activities in cells. Previous studies showed that ${\alpha}$-amanitin affects in vitro maturation of cumulus-oocyte-complex (COC). In this study, we evaluated the target of ${\alpha}$-amanitin, and whether it affects oocytes or cumulus cells (CCs), or both. We treated ${\alpha}$-amanitin with different time period during in vitro culture of denuded oocytes (DOs) or COCs in comparison, and observed the changes in morphology and maturation status. Although DOs did not show any change in morphology and maturation rates with ${\alpha}$-amanitin treatment, oocytes from COCs were arrested at metaphase I (MI) stage and CCs were more scattered than control groups. To discover causes of meiotic arrest and scattering of CCs, we focused on changes of cumulus expansion, gap junctions, and cellular metabolism which to be the important factors for the successful in vitro maturation of COCs. Expression of genes for cumulus expansion markers (Ptx3, Has2, and Tnfaip6) and gap junctional proteins (Gja1, Gja4, and Gjc1) decreased in ${\alpha}$-amanitin-treated CCs. However, these changes were not observed in oocytes. In addition, expression of genes related to metabolism (Prps1, Rpe, Rpia, Taldo1, and Tkt) decreased in ${\alpha}$-amanitin-treated CCs but not in oocytes. Therefore, we concluded that the transcriptional activities of CCs for supporting suitable transcripts, especially for its metabolic activities and formation of gap junctions among CCs as well as with oocytes, are important for oocytes maturation in COCs.

• Journal of Embryo Transfer
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• v.11 no.3
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• pp.233-240
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• 1996

This study was carried out to determine the effect of cumulus cell attachment and various factors on in vitro maturation of pig foflicular oocytes. Oocytes with various configuration of cumulus cell mass were collected ftom ovaries of mature gilts by asperating with syringe equipped with needles of different gauges, follicle size and with or without cumulus cells. They were cultured in TCM-199 mediun containing FGS(fetal calf serum) for 30~48 hours in incubator with air containing 5% $CO_2$ at 38.5$^{\circ}C$. Mter orcein staining at in vitro maturation condition, GV, GVBD, anaphase, telophase and M II were observed. Results are surumarized as follows: 1. Recovery rates were 55.8, 55.5 and 34.4% when the cumulus-compacted oocytes were collected with 18, 21, 26 gauge needles of syringes, respectively. 2. 79% of oocytes with compacted cumulus cells were at GV stage and most of the oocytes with partially denuded and denuded cumulus cells were from GVBD to M- II stages. 3. Percentage of mature oocytes among those which are follicular diameter of 1~2, 3~6 and over 6 mm was 42.6, 53.2 and 60.8%, respectively. 4. Percentage of mature oocytes among those which are compacted, partially denuded and denuded was 60.5, 46.2 and 35.4% respectively. 5. Percentage of mature oocytes in co-cultured with monolayers of cumulus cells was higher (57.1%) than that found with oocytes cultured alone (53.4%).

• Korean Journal of Animal Reproduction
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• v.14 no.4
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• pp.263-271
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• 1990

This study was carried out to investigate the factors affecting maturation in vitro of follicular oocytes in Korean Native Cattle. The bovine ovaries were obtained at a slaughter house and the follicular oocytes were recovered by aspirating the follicular fluid from the visible follicles of 3~6mm. The bovine oocytes were matured in vitro in TCM-199 containing FCS and hormones. The effects of TCM-199 salt type, number of oocytes per drop, incubation time and co-culture with granulosa cells on maturation of oocytes, were investigated. The results obtained are summarized as follows. 1. The maturation rates of follicular oocytes cultured for 22, 25 and 28 hours in Hank's TCM-199 or Earle's TCM-199 were 59.3, 59.6, 80% and 80.0, 90.0, 93.7%, respectively. The maturation rate of follicular oocytes in Earle's TCM-199 was faster and higher than in Hank's TCM-199(P<0.05). 2. The maturation rates of oocytes were 54.5, 62.5 and 62.0% when cultured the oocytes number 10, 20 and 40 per 200${mu}ell$ drop for 18 hours. 3. The maturation of follicular oocytes in the Korean Native Cattle was induced at 14 hours culture, by giving the maturation rate of 90.0% after 20 hours. 4. The maturation rates were 63.3% and 66.7%, respectigely when the oocytes were co-cultured with granulosa cells from medium-size follicles used immediately after recovery in the presence or absence of hormones added(0.02AU/ml FSH, 10$\mu\textrm{g}$/ml LH and 1$\mu\textrm{g}$/ml estradiol 17-$\beta$). When the oocytes were co-cultured with granulosa cells from medium-size follicles cultured for 3 days, the maturation rates were 20.8% and 76.2%, respectively(P<0.05). 5. The maturation rate were 88.0% and 70.0%, respectively when the oocytes were co-cultured with granulosa cells from large-size follicles used immediately after recovery in the presence or absence of hormones added(0.02AU/ml FSH, 10$\mu\textrm{g}$/ml LH and 1$\mu\textrm{g}$/ml estradiol 17-$\beta$)(P<0.05). When the hormones added(0.02AU/ml FSH, 10$\mu\textrm{g}$/ml LH and 1$\mu\textrm{g}$/ml estradiol 17-$\beta$)(P<0.05). When the oocytes were co-cultred with granulosa cells from large-size follicles cultured for 3 days, the maturation rates were 41.2% and 73.3%, respectively(P<0.05).

• Clinical and Experimental Reproductive Medicine
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• v.45 no.4
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• pp.189-194
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• 2018

Objective: The aim of this study was to compare the rate of maturation, fertilization, and embryo development of in vitro-matured human oocytes derived from pregnant and non-pregnant women. Methods: Immature oocytes were obtained by needle aspiration from 49 pregnant women (group 1) who underwent a cesarean section at term and 77 non-pregnant women (group 2) who underwent a gynecological operation during the same period (8 months). Healthy immature oocytes (530 in group 1 and 539 in group 2) were cultured and assessed for maturation 36 hours later. Mature oocytes were inseminated by intracytoplasmic sperm injection and cultured up to 144 hours. Results: The percentage of degenerated oocytes was significantly higher (12.1% vs. 6.3%; p<0.001) in group 1 than in group 2. There was no significant difference in the maturation rate (66.8% vs. 68.1%; p=0.698), fertilization rate (66.7% vs. 67.6%; p=0.857), or the rate of formation of good-quality blastocysts (46.2% vs. 47.2%; p=0.898) in oocytes obtained from pregnant and non-pregnant women. Conclusion: The developmental competence of immature oocytes did not differ between pregnant and non-pregnant women.