Identification of unbalanced complex chromosomal rearrangements in IVF-derived embryos during NGS analysis of preimplantation genetic testing: A case report

Complex chromosome rearrangements (CCRs) are structural chromosomal rearrangements involving at least three chromosomes and more than two breakpoints. CCR carriers are generally phenotypically normal but related to higher risk of recurrent miscarriage and having abnormal offspring with congenital anomalies. However, most of CCR carriers are not aware of their condition until genetic analysis of either abortus or affected baby or parental karyotyping is performed. Herein, we present the case that CCR carrier patients can be identified by preimplantation genetic testing of preimplantation embryos. An infertile male patient with severe oligoasthenoteratozoospermia was diagnosed balanced reciprocal translocation, 46,XY,t(3;11) (p26;p14) at first. After attempting the first preimplantation genetic testing for structural rearrangement (PGT-SR) cycle, we found the recurrent segmental gain or loss on 21q21.3-q22.3 of five out of nine embryos. As a result of karyotype re-analysis, the patient’s karyotype showed a balanced CCR involving chromosomes 3, 11, and 21 with three breakpoints 3p26, 11p14, and 21q21. The patient underwent two PGT-SR cycles, and a pregnancy was established after the transfer of an euploid embryo in the second cycle. Amniocentesis confirmed that the baby carried normal karyotype without mosaicism. At 37 weeks gestation, a healthy girl weighting 3,050 g was born.

Outdoor air pollution and diminished ovarian reserve among infertile Korean women

BACKGROUND@#Mounting evidence implicates an association between ambient air pollution and impaired reproductive potential of human. Our study aimed to assess the association between air pollution and ovarian reserve in young, infertile women.@*METHODS@#Our study included 2276 Korean women who attended a single fertility center in 2016-2018. Women's exposure to air pollution was assessed using concentrations of particulate matter (PM@*RESULTS@#The mean age was 36.6 ± 4.2 years and AMH level was 3.3 ± 3.1 ng/mL in the study population. Average AMH ratio was 0.8 ± 0.7 and low AMH was observed in 10.3% of women (n=235). The average concentration of six air pollutants was not different between the normal ovarian reserve and low AMH groups for all averaging periods. In multivariable models, an interquartile range (IQR)-increase in 1 month-average PM@*CONCLUSIONS@#In a cohort of infertile Korean women, there was a suggestive evidence of the negative association between ambient PM concentration and ovarian reserve, highlighting the potential adverse impact of air pollution on women's fertility.

The association of stromal antigen 3 (STAG3) sequence variations with spermatogenic impairment in the male Korean population / 亚洲男科学杂志(英文版)

The stromal antigen 3 (STAG3) gene, encoding a meiosis-specific cohesin component, is a strong candidate for causing male infertility, but little is known about this gene so far. We identified STAG3 in patients with nonobstructive azoospermia (NOA) and normozoospermia in the Korean population. The coding regions and their intron boundaries of STAG3 were identified in 120 Korean men with spermatogenic impairments and 245 normal controls by using direct sequencing and haplotype analysis. A total of 30 sequence variations were identified in this study. Of the total, seven were exonic variants, 18 were intronic variants, one was in the 5'-UTR, and four were in the 3'-UTR. Pathogenic variations that directly caused NOA were not identified. However, two variants, c.3669+35C>G (rs1727130) and +198A>T (rs1052482), showed significant differences in the frequency between the patient and control groups (P = 0.021, odds ratio [OR]: 1.79, 95% confidence interval [CI]: 1.098-2.918) and were tightly linked in the linkage disequilibrium (LD) block. When pmir-rs1052482A was cotransfected with miR-3162-5p, there was a substantial decrease in luciferase activity, compared with pmir-rs1052482T. This result suggests that rs1052482 was located within a binding site of miR-3162-5p in the STAG3 3'-UTR, and the minor allele, the rs1052482T polymorphism, might offset inhibition by miR-3162-5p. We are the first to identify a total of 30 single-nucleotide variations (SNVs) of STAG3 gene in the Korean population. We found that two SNVs (rs1727130 and rs1052482) located in the 3'-UTR region may be associated with the NOA phenotype. Our findings contribute to understanding male infertility with spermatogenic impairment.

Could surgical management improve the IVF outcomes in infertile women with endometrioma?: a review

Endometriosis is a chronic inflammatory condition that affects fertility and could be toxic to the ovary. Endometrioma per se and surgical interventions for endometrioma significantly reduce the ovarian reserve. Therefore, to prepare for surgical intervention for endometrioma, the high-risk group with decreased ovarian reserve must be considered. There is no evidence to support the use of surgical intervention before in vitro fertilization (IVF) to improve the reproductive outcomes of subsequent IVF in infertile women with advanced-stage endometriosis or endometrioma. As surgical treatment has few benefits, IVF could be recommended immediately for aiding conception in these women. However, the reproductive prognosis of IVF may be worse in the more advanced stages of endometriosis. When dysmenorrhea is severe or when cancer is suspected, surgery prior to IVF may be necessary and justified. When the size of the endometrioma is very large, surgery could be required prior to IVF to facilitate access to follicles during oocyte retrieval or to improve the ovarian response to controlled ovarian stimulation. Prolonged pituitary downregulation in women with surgically diagnosed endometriosis may be helpful to increase the clinical pregnancy rate in subsequent IVF cycles. The purpose of this paper was to review the efficiency and clinical application of the surgical intervention and IVF for infertile women with advanced-stage endometriosis or endometrioma.

Correlation between Morphologic Grading and Euploidy Rates of Blastocysts, and Clinical Outcomes in In Vitro Fertilization Preimplantation Genetic Screening

BACKGROUND: The standard morphological evaluation has been widely used for embryo selection, but it has limitations. This study aimed to investigate the correlation between morphologic grading and euploidy rate of in vitro fertilization (IVF) preimplantation genetic screening (PGS) and compare the pregnancy rates in young and old ages. METHODS: This is a retrospective study using the medical records of patients who underwent IVF procedures with PGS between January 2016 and February 2017 in a single center. The embryo grades were categorized into 4 groups: excellent, good, fair, and poor. Basic characteristics, euploidy rates, clinical pregnancy (CP) rates and ongoing pregnancy rates were analyzed. RESULTS: The excellent group had significantly higher rate of euploid embryos than fair group (47.82% vs. 29.33%; P = 0.023) and poor group (47.82% vs. 29.60%; P = 0.005). When the four groups were recategorized into two groups (excellent and good vs. fair and poor), they also showed significant difference in euploidy rates (44.52% vs. 29.53%; P = 0.002). When the patients were divided into two groups by age 35, the CP rates for those under and over 35 years old were 44.74% and 47.83%, respectively, which showed no significant difference. CONCLUSION: The significant differences among the euploidy rates of different morphologic embryo grades demonstrated the positive correlations between the morphologic grading of the embryo and the euploidy rate of PGS. Additionally, there was no significant difference between the younger and older patients' CP rates. These findings emphasize the fact that old age patients might benefit from PGS whatever the indication of PGS is.

Application of serum anti-Müllerian hormone levels in selecting patients with polycystic ovary syndrome for in vitro maturation treatment / 대한생식의학회지

OBJECTIVE: The purpose of this study was to identify useful clinical factors for the identification of patients with polycystic ovary syndrome (PCOS) who would benefit from in vitro maturation (IVM) treatment without exhibiting compromised pregnancy outcomes. METHODS: A retrospective cohort study was performed of 186 consecutive patients with PCOS who underwent human chorionic gonadotropin-primed IVM treatment between March 2010 and March 2014. Only the first IVM cycle of each patient was included in this study. A retrospective case-control study was subsequently conducted to compare pregnancy outcomes between IVM and conventional in vitro fertilization (IVF) cycles. RESULTS: Through logistic regression analyses, we arrived at the novel finding that serum anti-Müllerian hormone (AMH) levels and the number of fertilized oocytes in IVM were independent predictive factors for live birth with unstandardized coefficients of 0.078 (95% confidence interval [CI], 1.005-1.164; p=0.037) and 0.113 (95% CI, 1.038-1.208; p=0.003), respectively. Furthermore, these two parameters were able to discriminate patients who experienced live births from non-pregnant IVM patients using cut-off levels of 8.5 ng/mL and five fertilized oocytes, respectively. A subsequent retrospective case-control study of patients with PCOS who had serum AMH levels ≥8.5 ng/mL showed that IVM had pregnancy outcomes comparable to conventional IVF, and that no cases of ovarian hyperstimulation syndrome were observed. CONCLUSION: Serum AMH levels are a useful factor for predicting pregnancy outcomes in PCOS patients before the beginning of an IVM cycle. IVM may be an alternative to conventional IVF for PCOS patients if the patients are properly selected according to predictive factors such as serum AMH levels.

Chronic endometritis and infertility / 대한생식의학회지

Chronic endometritis (CE) is a condition involving the breakdown of the peaceful co-existence between microorganisms and the host immune system in the endometrium. A majority of CE cases produce no noticeable signs or mild symptoms, and the prevalence rate of CE has been found to be approximately 10%. Gynecologists and pathologists often do not focus much clinical attention on CE due to the time-consuming microscopic examinations necessary to diagnose CE, its mild clinical manifestations, and the benign nature of the disease. However, the relationship between CE and infertility-related conditions such as repeated implantation failure and recurrent miscarriage has recently emerged as an area of inquiry. In this study, we reviewed the literature on the pathophysiology of CE and how it may be associated with infertility, as well as the literature regarding the diagnosis and treatment of CE. In addition, we discuss the value of hysteroscopic procedures in the diagnosis and treatment of CE.

The meaning of anti-Müllerian hormone levels in patients at a high risk of poor ovarian response / 대한생식의학회지

Measurements of ovarian reserve play an important role in predicting the clinical results of assisted reproductive technology (ART). The ideal markers of ovarian reserve for clinical applications should have high specificity in order to determine genuine poor responders. Basal follicle-stimulating hormone levels, antral follicle count, and serum anti-Müllerian hormone (AMH) levels have been suggested as ovarian reserve tests that may fulfill this requirement, with serum AMH levels being the most promising parameter. Serum AMH levels have been suggested to be a predictor of clinical pregnancy in ART for older women, who are at a high risk for decreased ovarian response. We reviewed the prognostic significance of ovarian reserve tests for patients undergoing ART treatment, with a particular focus on the significance of serum AMH levels in patients at a high risk of poor ovarian response.

Anti-Mullerian hormone levels as a predictor of clinical pregnancy in in vitro fertilization/intracytoplasmic sperm injection-embryo transfer cycles in patients over 40 years of age / 대한생식의학회지

OBJECTIVE: The aim of the current study was to determine the predictive value of anti-Mullerian hormone (AMH) levels for pregnancy outcomes in patients over 40 years of age who underwent in vitro fertilization or intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) cycles. METHODS: We retrospectively analyzed the medical records of 188 women aged 40 to 44 years who underwent IVF/ICSI-fresh ET cycles due to unexplained infertility in the fertility center of CHA Gangnam Medical Center. Patients were divided into group A, with AMH levels or =1.0 ng/mL (n=91). We compared the clinical pregnancy rate (CPR) in the two groups and performed logistic regression analysis to identify factors that had a significant effect on the CPR. RESULTS: The CPR was significantly lower in group A than group B (7.2% vs. 24.2%, p or =1.90 ng/mL than in the group with AMH levels <1.90 ng/mL (p<0.001). CONCLUSION: Our study showed that AMH levels were predictive of clinical pregnancy in infertility patients over 40 years of age. Further prospective studies should be conducted to validate the predictive capability of AMH levels for the outcome of clinical pregnancy.

A healthy delivery of twins by assisted reproduction followed by preimplantation genetic screening in a woman with X-linked dominant incontinentia pigmenti / 대한생식의학회지

The purpose of this study is to report a successful twin pregnancy and delivery in a female patient with X-linked dominant incontinentia pigmenti (IP) who underwent assisted reproductive technology followed by preimplantation genetic screening (PGS). A 29-year-old female with IP had a previous history of recurrent spontaneous abortion. A molecular analysis revealed the patient had a de novo mutation, 1308_1309insCCCCTTG(p.Ala438ProfsTer26), in the inhibitor of the kappa B kinase gamma gene located in the Xq28 region. IVF/ICSI and PGS was performed, in which male embryos were sexed using array-based comparative genomic hybridization (aCGH). After IVF/ICSI and PGS using aCGH on seven embryos, two euploid male blastocysts were transferred with a 50% probability of a viable male pregnancy. The dizygotic twin pregnancy was confirmed and the amniocentesis results of each twin were normal with regard to the mutation found in the mother. The patient delivered healthy twin babies during the 37th week of gestation. This case shows the beneficial role of PGS in achieving a successful pregnancy through euploid male embryo gender selection in a woman with X-linked dominant IP with a history of multiple male miscarriages.

Spontaneous ovarian hyperstimulation syndrome following a thawed embryo transfer cycle / 대한생식의학회지

This article reports a case of spontaneous ovarian hyperstimulation syndrome (OHSS) following a thawed embryo transfer cycle. OHSS, a potentially life-threatening condition, is an iatrogenic complication of controlled ovarian stimulation; therefore, it is very important to prevent and treat OHSS during treatment with ovulation-inducing agents. Despite our efforts to prevent OHSS, in this case, severe spontaneous OHSS occurred, which resulted in uncontrolled preterm labor and a preterm delivery and also persisted for 6 weeks after delivery. Freezing all embryos cannot entirely prevent the development of OHSS because OHSS can occur spontaneously. Although spontaneous OHSS remains a rare event, females with a history of OHSS may have an elevated risk for spontaneous OHSS. We suggest closely monitoring cases of pregnancy following thawed embryo transfer for early diagnosis of spontaneous OHSS and the use of conservative management.

Correlation between Expression of Glucose Transporters in Granulosa Cells and Oocyte Quality in Women with Polycystic Ovary Syndrome

BACKGROUND: The glucose transporters (GLUTs) exhibit different tissue-specific expression. This study aimed to investigate the types of GLUTs expressed in human granulosa cells (GCs) obtained from women with polycystic ovary syndrome (PCOS) and their relationship with insulin resistance (IR) and the outcomes of in vitro maturation (IVM) of immature oocytes. METHODS: Expression of GLUTs was evaluated in GCs from women with PCOS with or without IR. Thirty-six women with PCOS undergoing an IVM program were included. Differential gene expression between the insulin sensitive (IS) and IR group was measured by reverse transcription polymerase chain reaction. RESULTS: Expression of GLUTs 1, 3, 5, 8, and 13 was constitutive, whereas expression of GLUTs 2 and 7 was not observed in human GCs. The remaining GLUTs, 4, 6, 9, 10, 11, and 12, were differentially expressed among patients according to metabolic status, such as insulin sensitivity. A higher number of GCs from patients with IR (92%) expressed GLUT6 than GCs from IS PCOS patients (46.3%). Logistic regression showed that expression of GLUTs 9, 11, and 12 correlates with rates of IVM at 48 hours, fertilization, and implantation, respectively. CONCLUSION: This is the first report describing the expression pattern of all 13 members of the GLUT family in human GCs. Results of the present study suggest that patients' insulin sensitivity regulates GLUT expression in GCs in PCOS patients, and this may control oocyte quality for IVM and subsequent processes such as fertilization and implantation in patients taking part in an in vitro fertilization program.

In vitro maturation of human oocytes: Its role in infertility treatment and new possibilities / 대한생식의학회지

IVM refers to the maturation of immature oocytes in culture after their recovery from small antral follicles at the stage prior to selection and dominance. IVM requires little or no FSH in vivo and has been proposed as an alternative to conventional IVF, since it reduces the primary adverse effects caused by controlled ovarian stimulation, including the ovarian hyperstimulation syndrome. Moreover, IVM is a promising option for cases for which no standard protocol is suitable, such as FSH resistance, contraindications for ovarian stimulatory drugs, and the need for urgent fertility preservation. Recently, IVM has been used in women with regular cycles and normal ovaries. However, the pregnancy rate following IVM is suboptimal compared with that of conventional IVF, indicating that further studies to optimize the protocol and the culture conditions are warranted.

Reversible Infertility Associated with Testosterone Therapy for Symptomatic Hypogonadism in Infertile Couple

PURPOSE: Androgen replacement therapy has been shown to be safe and effective for most patients with testosterone deficiency. Male partners of infertile couples often report significantly poorer sexual activity and complain androgen deficiency symptoms. We report herein an adverse effect on fertility caused by misusage of androgen replacement therapy in infertile men with hypogonadal symptoms. MATERIALS AND METHODS: The study population consisted of 8 male patients referred from a local clinic for azoospermia or severe oligozoospermia between January 2008 and July 2011. After detailed evaluation at our andrology clinic, all patients were diagnosed with iatrogenic hypogonadism associated with external androgen replacement. We evaluated changes in semen parameters and serum hormone level, and fertility status. RESULTS: All patients had received multiple testosterone undecanoate (NebidoR) injections at local clinic due to androgen deficiency symptoms combined with lower serum testosterone level. The median duration of androgen replacement therapy prior to the development of azoospermia was 8 months (range: 4-12 months). After withdrawal of androgen therapy, sperm concentration and serum follicle-stimulating hormone level returned to normal range at a median 8.5 months (range: 7-10 months). CONCLUSION: Misusage of external androgen replacement therapy in infertile men with poor sexual function can cause temporary spermatogenic dysfunction, thus aggravating infertility.

A case of the rare variant of Klinefelter syndrome 47,XY,i(X)(q10) / 대한생식의학회지

Klinefelter syndrome is the most common genetic form of male hypogonadism, but the phenotype becomes evident only after puberty. It is characterized by infertility, small testes, sparse body and facial hair, increased body weight, gynecomastia, increased LH and FSH, and a low level of testosterone. Early recognition and treatment of Klinefelter syndrome can significantly improve the patient's quality of life and prevent serious consequences. Here, we report an infertile man with a rare variant of Klinefelter syndrome with a 47, XY, i(X)(q10) karyotype.

Current status of assisted reproductive technology in Korea, 2009

Great advances have been made in the field of assisted reproductive technology (ART) since the first in vitro fertilization (IVF) baby was born in Korea in the year of 1985. However, it deserve to say that the invaluable data from fertility centers may serve as a useful source to find out which factors affect successful IVF outcome and to offer applicable information to infertile patients and fertility clinics. This article intended to report the status of ART in 2009 Korean Society of Obstetrics and Gynecology surveyed. The current survey was performed to assess the status and success rate of ART performed in Korea, between January 1 and December 31, 2009. Reporting forms had been sent out to IVF centers via e-mail, and collected by e-mail as well in 2012. With International Committee Monitoring Assisted Reproductive Technologies recommendation, intracytoplasmic sperm injection (ICSI) and non-ICSI cases have been categorized and also IVF-ET cases involving frozen embryo replacement have been surveyed separately. Seventy-four centers have reported the treatment cycles initiated in the year of 2009, and had performed a total of 27,947 cycles of ART treatments. Among a total of 27,947 treatment cycles, IVF and ICSI cases added up to 22,049 (78.9%), with 45.3% IVF without ICSI and 54.7% IVF with ICSI, respectively. Among the IVF and ICSI patients, patients confirmed to have achieved clinical pregnancy was 28.8% per cycle with oocyte retrieval, and 30.9% per cycle with embryo transfer. The most common number of embryos transferred in 2009 is three embryos (40.4%), followed by 2 embryos (28.4%) and a single embryo transferred (13.6%). Among IVF and ICSI cycles that resulted in multiple live births, twin pregnancy rate was 45.3% and triple pregnancy rate was 1.1%. A total of 191 cases of oocyte donation had been performed to result in 25.0% of live birth rate. Meanwhile, a total of 5,619 cases of frozen embryo replacement had been performed with 33.7% of clinical pregnancy rate per cycle with embryo transfer. When comparing with international registry data, clinical pregnancy rate per transfer from fresh IVF cycles including ICSI (34.1%,) was comparable to clinical pregnancy rate per transfer in European Society for Human Reproduction and Embryology report was 32.5% though lower than 45.0% for USA data. There was no remarkable difference in status of assisted reproductive technology in Korea between the current report and the data reported in 2008. The age of women trying to get pregnant was reconfirmed to be the most important factor that may have impact on success of ART treatment.

Function of the pentose phosphate pathway and its key enzyme, transketolase, in the regulation of the meiotic cell cycle in oocytes / 대한생식의학회지

OBJECTIVE: Previously, we identified that transketolase (Tkt), an important enzyme in the pentose phosphate pathway, is highly expressed at 2 hours of spontaneous maturation in oocytes. Therefore, this study was performed to determine the function of Tkt in meiotic cell cycle regulation, especially at the point of germinal vesicle breakdown (GVBD). METHODS: We evaluated the loss-of-function of Tkt by microinjecting Tkt double-stranded RNAs (dsRNAs) into germinal vesicle-stage oocytes, and the oocytes were cultured in vitro to evaluate phenotypic changes during oocyte maturation. In addition to maturation rates, meiotic spindle and chromosome rearrangements, and changes in expression of other enzymes in the pentose phosphate pathway were determined after Tkt RNA interference (RNAi). RESULTS: Despite the complete and specific knockdown of Tkt expression, GVBD occurred and meiosis was arrested at the metaphase I (MI) stage. The arrested oocytes exhibited spindle loss, chromosomal aggregation, and declined maturation promoting factor and mitogen-activated protein kinase activities. The modified expression of two enzymes in the pentose phosphate pathway, Prps1 and Rbks, after Tkt RNAi and decreased maturation rates were amended when ribose-5-phosphate was supplemented in the culture medium, suggesting that the Tkt and pentose phosphate pathway are important for the maturation process. CONCLUSION: We concluded that Tkt and its associated pentose phosphate pathway play an important role in the MI-MII transition of the oocytes' meiotic cell cycle, but not in the process of GVBD.

What is the best treatment of heterotopic cervical pregnancies for a successful pregnancy outcome? / 대한생식의학회지

Heterotopic pregnancy is rare event and the risk is increased with assisted reproductive technology procedures. Heterotopic cervical pregnancy is even more unusual. We report a rare case of heterotopic cervical pregnancy that was managed successfully. A 36-year-old women who conceived by IVF-ICSI was diagnosed with heterotopic cervical pregnancy. She visited the emergency room with vaginal bleeding at 5 weeks of gestation and underwent careful intracervical gestational sac reduction with forceps under abdominal guidance the next day. The postoperative course was uneventful and with regular check-ups, the intrauterine pregnancy (IUP) progressed unremarkably through 41 weeks with delivery of a healthy newborn. We reviewed a total of 37 cases of heterotopic pregnancy that have been reported in the English language literature. There have been many attempts to eliminate the cervical embryo while preserving the IUP, and complete cervical evacuation is important in order to avoid infection, bleeding, and premature birth.

Efficiency of laser-assisted intracytoplasmic sperm injection in a human assisted reproductive techniques program / 대한생식의학회지

OBJECTIVE: Laser-assisted intracytoplasmic sperm injection (LA-ICSI), also known as micro-opening or thinning of the zona pellucida (ZP) prior to ICSI, may help to reduce mechanical damage to the oocyte during the procedure. The aim of the present study was to evaluate and analyze the efficacy of our institutional LA-ICSI program, which features laser-assisted ZP thinning prior to ICSI, in comparison with conventional ICSI (C-ICSI), performed on patients with different clinical characteristics. METHODS: Patients undergoing a total of 212 ICSI cycles were randomly divided into an LA-ICSI group (106 cycles) and a conventional ICSI group (106 cycles). To reduce tissue damage, we thinned the ZP by approximately 70%, using a laser, before ICSI. Patients thus treated formed the LA-ICSI group. Comparisons included the morphological quality of transferred embryos, blastocyst development of the remaining embryos, and clinical pregnancy, in terms of ICSI method and patient characteristics. RESULTS: Fertilization, development of remaining embryos, and pregnancy rate were significantly higher in the LA-ICSI group compared with the C-ICSI group. Fertilization, embryonic development, and the pregnancy rate were all improved in younger patients (<38 years of age) and in those who underwent a low number of IVF-ET attempts (<3 trials). In addition, the pregnancy rate was increased in older patients. CONCLUSION: LA-ICSI may be useful in improving the chance of pregnancy in all ICSI patients.

Expression of interferon regulatory factor-1 in the mouse cumulus-oocyte complex is negatively related with oocyte maturation / 대한생식의학회지

OBJECTIVE: We found previously that interferon regulatory factor (Irf)-1 is a germinal vesicle (GV)-selective gene that highly expressed in GV as compared to metaphase II oocytes. To our knowledge, the function of Irf-1 in oocytes has yet to be examined. The present study was conducted to determine the relationship between retinoic acid (RA) and RA-mediated expression of Irf-1 and the mouse oocyte maturation. METHODS: Immature cumulus-oocyte-complexes (COCs) were collected from 17-day-old female mice and cultured in vitro for 16 hours in the presence of varying concentrations of RA (0-10 microM). Rate of oocyte maturation and activation was measured. Gene expression was measured by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) and cytokine secretion in the medium was measured by Bio-Plex analysis. Apoptosis was analyzed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. RESULTS: The rates of oocyte maturation to metaphase II and oocyte activation increased significantly with RA treatment (10 nM-1 microM). With 100 nM RA treatment, lowest level of Irf-1 mRNA and cumulus cell's apoptosis was found. Among 23 cytokines measured by Bio-Plex system, the substantial changes in secretion of tumor necrosis factor-alpha, macrophage inflammatory protein-1beta, eotaxin and interleukin-12 (p40) from COCs in response to RA were detected. CONCLUSION: We concluded that the maturation of oocytes and Irf-1 expression are negatively correlated, and RA enhances the developmental competence of mouse immature oocytes in vitro by suppressing apoptosis of cumulus cells. Using a mouse model, results of the present study provide insights into improved culture conditions for in vitro oocyte maturation and relevant cytokine production and secretion in assisted reproductive technology.