Immature oocyte retrieval combined with in-vitro oocyte maturation

In vitro maturation (IVM) of human immature oocytes: is it still relevant?

In vitro maturation (IVM) of human immature oocytes has been shown to be a viable option for patients at risk of ovarian hyperstimulation syndrome (OHSS), those seeking urgent fertility preservation and in circumstances where controlled ovarian stimulation is not feasible. Moreover, IVM techniques can be combined with ovarian tissue cryobanking to increase the chances of conception in cancer survivors. The clinical applications of IVM in the field of reproductive medicine are rapidly expanding and the technique is now classified as non-experimental. In contrast to conventional IVF (in vitro fertilization), IVM offers several advantages, such as reduced gonadotropin stimulation, minimal risk of ovarian hyperstimulation syndrome (OHSS), reduced treatment times and lower costs. However, the technical expertise involved in performing IVM and its lower success rates compared to traditional IVF cycles, still pose significant challenges. Despite recent advances, such as innovative biphasic IVM systems, IVM is still an evolving technique and research is ongoing to refine protocols and identify techniques to improve its efficiency and effectiveness. A comprehensive understanding of the distinct mechanisms of oocyte maturation is crucial for obtaining more viable oocytes through in vitro methods, which will in turn lead to significantly improved success rates. In this review, the present state of human IVM programs and future research directions will be discussed, aiming to promote a better understanding of IVM and identify potential strategies to improve the overall efficiency and success rates of IVM programs, which will in turn lead to better clinical outcomes.

Testosterone supplementation improves estrogen synthesis of buffalo (Bubalus bubalis) granulosa cells

Granulosa cells (GCs) synthesize estrogens needed for follicular growth. However, the effects of androgen on estrogen production in buffalo GCs remain unclear. In this study, the impacts of testosterone on estrogen synthesis in buffalo GCs were examined. The results showed that testosterone that was added to cell medium at a concentration of 10-7  mol/L and applied to GCs for 48 or 72 h enhanced the estrogen synthesis of buffalo GCs. This study provides a theoretical basis for further exploration of ovarian endocrine mechanism for steroidogenesis.

Hypoxia enhances steroidogenic competence of buffalo (Bubalus bubalis) granulosa cells

Granulosa cells (GCs) synthesize estrogens needed for follicular growth. However, the effects of hypoxia on steroidogenesis in buffalo GCs remain unclear. In this study, the impacts of hypoxic conditions (5% oxygen) on estrogen synthesis in buffalo GCs were examined. The results showed that hypoxia improved both the expression levels of estrogen synthesis-related genes (CYP11A1, CYP19A1, and 3β-HSD) and the secretion levels of estradiol in buffalo GCs. Hypoxic conditions promoted the sensitivity of buffalo GCs to FSH. Furthermore, inhibition of cAMP/PKA signaling pathway (H89, a cAMP/PKA signaling pathway inhibitor) reduced both the expression levels of estrogen synthesis-related genes (CYP11A1, CYP19A1, and 3β-HSD) and the secretion levels of estradiol in hypoxia-cultured buffalo GCs. Besides, inhibition of cAMP/PKA signaling pathway lowered the responsiveness of buffalo GCs to FSH under hypoxic conditions. The present study indicated that hypoxia enhanced the steroidogenic competence of buffalo GCs principal by affecting cAMP/PKA signaling pathway and subsequent sensitivity of GCs to FSH.

Granulosa Cells Improved Mare Oocyte Cytoplasmic Maturation by Providing Collagens

Assisted reproductive technology has important clinical applications and commercial values in the horse industry. However, this approach is limited largely by the low efficiency of oocyte in vitro maturation (IVM), especially cytoplasmic maturation. To improve the efficiency of mare oocyte IVM, we evaluated the effects of co-culture with cumulus–oocyte complexes (COCs) and granulosa cells (GCs) from follicles with small (<15 mm) and large diameters (>35 mm). Our results showed that oocyte nucleus maturation was not significantly improved by co-culturing with GCs. Interestingly, the cytoplasmic maturation of oocytes, defined by the distribution of cortical granules and mitochondria, as well as reactive oxygen species (ROS) levels, improved dramatically by co-culture with GCs, especially those derived from small follicles. Moreover, GCs promoted cumulus cell expansion by upregulating the expression of BMP15 in oocytes. To determine the mechanism underlying the effects of GCs, the transcriptomes of GCs from large and small follicles were compared. Expression levels of COL1A2, COL6A1, and COL6A2 were significantly higher in GCs from small follicles than in those from large follicles. These three genes were enriched in the extracellular matrix proteins-receptor interaction pathway and were involved in the regulation of collagens. Taken together, our results suggest that co-culture with GCs is beneficial to oocyte cytoplasmic maturation, and the increased expression of COL1A2, COL6A1, and COL6A2 improve the mare oocyte IVM system via the regulation of collagen.

Effect of dominant follicle status at the time of retrieval on the clinical outcomes in natural cycle IVF combined with immature oocyte treatment

Objective: It is commonly believed that the oocytes from small follicles are unhealthy when a dominant follicle (DF) is recruited in the ovaries, especially when the DF is ovulated. This study aims to confirm whether the presence or ovulation of DF at the time of retrieval affects the clinical outcome of the natural cycle IVF with in vitro maturation (NC-IVF/M) treatment.

Methods: Data were collected from 446 women with regular menstrual cycle and 536 retrieval cycles using NC-IVF/M treatment. The cycles were divided into three groups based on the results of the oocyte retrieval cycle. Group A covers the collection of oocytes from the DF and small follicles; Group B incorporates failed oocyte retrieval from DF and then the oocytes are retrieved only from small follicles; and Group C includes the retrieval of oocytes only from small follicles accompanied with an ovulated DF. Furthermore, Group B and C have subgroups to include whether in vivo matured oocytes were obtained from small follicles. Following aspiration of DF and small follicles, mature oocytes were inseminated on the date of retrieval by intracytoplasmic sperm injection (ICSI) and the immature oocytes were matured in vitro. If the immature oocytes were matured in vitro, they were inseminated using ICSI, and then the embryos obtained from in vivo and in vitro matured oocytes were transferred accordingly.

Results: The oocytes from DF were successfully retrieved in 445 cycles (83.0%), failed to be retrieved in 54 cycles (10.1%) and ovulated in 37 cycles (6.9%). In Group A, an average of 2.0 ± 1.7 mature oocytes were retrieved, which was significantly higher than the average of Group B, with 1.3 ± 1.3 matured oocytes and Group C, with an average of 1.1 ± 1.5 matured oocytes (P < 0.01). However, the average number of immature oocytes retrieved from each group show no difference among the three groups. There was no significant difference in maturation rates of immature oocytes, fertilization rates among the three groups. The clinical pregnancy rate per transfer cycle is 34.5%, 34.6% and 25.7% in Group A, B and C, respectively. No significant differences were observed in embryonic development and implantation capacity in Group B and C in comparison to Group A. And there was no significant difference in clinical pregnancy, implantation, live birth and miscarriage rates among the three groups. No significant differences were observed in the developmental and implantation capacity according to with or without in vivo matured oocytes were retrieved in Group B and Group C.

Conclusion: The presence or ovulation of the dominant follicle from the ovaries does not significantly influence the developmental and implantation capacity of immature oocytes retrieved from small follicles, suggesting that NC-IVF/M is a promising treatment option for women without ovarian stimulation.

Granulosa cells affect in vitro maturation and subsequent parthenogenetic development of buffalo (Bubalus bubalis) oocytes

Granulosa cells (GCs) play a crucial role in follicular development and atresia. Previous studies have showed that GCs in the form of monolayer influenced in vitro maturation (IVM) of oocytes. However, the effects of GCs in the form of conditioned medium and monolayer on IVM and development competence of buffalo oocytes remain unclear. In the present study, we examined the impacts of GC-conditioned medium (GCCM) and monolayer GC on maturation efficiency and embryo development of buffalo oocytes after parthenogenetic activation (PA). Our results showed that GCCM that was collected on day 2 and added to IVM medium at a 20% proportional level (2 days and 20%) exerted significant negative effects on IVM rate (41.6% vs. 44.5%), but significantly enhanced embryo development (oocyte cleavage, 81.3% vs. 69.3%; blastocyst formation, 36.3% vs. 29.3%) of buffalo oocytes after PA compared with the control group. Furthermore, monolayer GC significantly reduced both maturation efficiency (40.2% vs. 44.5%) and embryo development (oocyte cleavage, 60.6% vs. 69.3%; blastocyst formation, 20.6% vs. 29.3%) of buffalo oocytes after PA compared to the control group. Our study indicated that GCs in the form of GCCM (2 days and 20%) and monolayer GC had different effects on IVM and subsequent parthenogenetic development of buffalo oocytes.

Enhancing Oocyte Competence With Milrinone as a Phosphodiesterase 3A Inhibitor to Improve the Development of Porcine Cloned Embryos

The objective of this study was to investigate the effect of milrinone supplementation as a phosphodiesterase 3A inhibitor during in vitro maturation (IVM) to coordinate the cytoplasmic and nuclear maturation of porcine oocytes and subsequent development of porcine cloned embryos. Brilliant cresyl blue (BCB)-stained (BCB +) oocytes, classified as well-developed, and BCB− oocytes were used in parthenogenesis (PA) and cloning, and their preimplantation development was compared. In PA embryos, BCB + oocytes had significantly higher rates of development than BCB− oocytes in terms of maturation (87.5 vs. 71.3%), cleavage (88.6 vs. 76.3%), and blastocyst development (34.3 vs. 25.3%) and also had higher cell numbers (46.9 vs. 38.9%), respectively (p < 0.05). In cloned embryos, the BCB + group also had a significantly higher blastocyst formation rate than the BCB− group (30.6 vs. 20.1%; p < 0.05). Supplementation with 75 μM milrinone during IVM of BCB− oocytes showed improvement in maturation and blastocyst development rates, which may be due to the coordinated maturation of the cytoplasm with the nucleus as an effect of milrinone. Moreover, the analysis of nuclear reprogramming via the examination of the expression levels of the reprogramming-related genes POU5F1, DPPA2, and NDP52IL in milrinone-supplemented BCB− oocytes showed higher expression levels than that in non-treated BCB− oocytes. These findings demonstrate that milrinone is useful in improving developmental competence in less competent oocytes during IVM and for proper nuclear reprogramming in the production of porcine cloned embryos by coordinating cytoplasmic and nucleus maturation.

COMPARISON OF MORPHOMETRIC AND MORPHOLOGY OOCYTES AFTER IN VITRO MATURATION BETWEEN HEALTHY WOMEN AND PATIENTS WITH POLYCYSTIC OVARIAN SYNDROME

Objectives

Polycystic ovarian syndrome (PCOS) occurs in 6-10% of all women in their reproductive age. In women with PCOS, controlled ovarian hyperstimulation (COH) often results in an increased risk of ovarian hyperstimulation syndrome (OHSS). In vitro maturation (IVM) of human oocyte is an alternative technique for in vitro fertilization (IVF). The aim of this study was to compare the morphometric analysis and morphology of oocytes after in- vitro maturation (IVM) between normal women and those suffering from polycystic ovary syndrome (PCOS).

Material and Methods

Thirty two women of 20 to 35 years of age that were undergoing controlled ovarian stimulation by the ICSI/IVF protocol were chosen for the study. The immature oocytes (n=108) were divided into two groups: the first oocyte group was comprised of 16 normal women (n=54); and the second group included 16 women with PCOS (n=54); then the oocytes were matured in vitro. After 24-48h of incubation, the oocyte maturation rate and morphometric and morphological characteristics were assessed using an inverted microscope, and then the images were compared.

Results

There were significant differences in the maturity of oocytes between normal women and those with PCOS after IVM (P<0.05). Moreover, morphometric assessments revealed that there were no significant difference in the total diameter (μm) (zona thickness (ZPT) + perivitelline space width (PVS) + cytoplasm (CD) of oocytes between normal women and those with PCOS (156.3±6.8 and 137.7±9.9), respectively (P>0.05). Evaluation of morphological oocytes showed that morphological abnormalities, including ooplasmic vacuolization and granulation were higher in PCOS women compared to normal women (P<0.05).

Conclusion

The increased quality of oocytes after IVM reflected a positive impact of IVM oocytes on normal women as compared to women with PCOS.

Vitrification of in vitro matured oocytes diminishes embryo development potential before but not after embryo genomic activation

PURPOSE

The aim of this study is to evaluate the impact of oocyte vitrification on embryo development potential and to assess the chromosome abnormalities of blastocysts derived from fresh/vitrified-warmed oocytes to assure the safety of the oocyte cryopreservation technique.

METHODS

In vitro matured oocytes derived from immature oocytes were retrieved from small follicles during IVF/intracytoplasmic sperm injection (ICSI) cycles were randomly divided into a fresh and vitrified-warmed groups. After intracytoplasmic sperm injection, the fertilization rate, embryo quality, and developmental status were compared between the two groups. Blastocysts derived from both groups were analyzed using the copy number variation (CNV)-seq technique to evaluate DNA abnormalities.

RESULTS

The fertilization rate with ICSI and the cleavage rate were similar between the two groups. Among the vitrified-warmed group, there was a lower incidence of usable embryos on day 3 (16.42 vs. 28.57 %; P < 0.05) and a lower incidence of blastocysts (7.46 vs. 17.86 %; P < 0.05). However, the proportions of embryos that developed to blastocysts from the day 3 available embryos were similar between the two groups (62.5 vs. 45.45 %; P > 0.05). In the day 3 embryos, the proportion of >5 cell embryos in the fresh group was markedly higher than in the vitrified-warmed group (41.67 vs. 21.64 %; P < 0.05), and the proportion of embryos with ≧50 % fragments was not significantly different between the two groups (39.29 vs. 43.28 %; P > 0.05). The result of CNV-seq demonstrated that there was no difference in chromosomal abnormalities between the two groups (20 vs. 20 %).

CONCLUSIONS

Oocyte vitrification and the warming procedure diminished the embryo development potential before day 3, when embryo genomic activation started. The day 3 usable embryos derived from vitrified-warmed oocytes had the same potential for developing into blastocysts. Vitrification and the warming procedure did not increase the chromosome abnormalities of the blastocysts. Oocyte vitrification is a safe technique for those patients who have no other options, although the oocyte efficiency may be diminished after the vitrified-warmed procedure.

The potential role of granulosa cells in the maturation rate of immature human oocytes and embryo development: A co-culture study

Objective

In order to increase the number of mature oocytes usable for intracytoplasmic sperm injection (ICSI), we aimed to investigate the effect of co-culturing granulosa cells (GCs) on human oocyte maturation in vitro, the fertilization rate, and embryo development.

Methods

A total of 133 immature oocytes were retrieved and were randomly divided into two groups; oocytes that were cultured with GCs (group A) and oocytes that were cultured without GCs (group B). After in vitro maturation, only oocytes that displayed metaphase II (MII) underwent the ICSI procedure. The maturation and fertilization rates were analyzed, as well as the frequency of embryo development.

Results

The mean age of the patients, their basal levels of follicle-stimulating hormone, and the number of oocytes recovered from the patients were all comparable between the two study groups. The number of oocytes that reached MII (mature oocytes) was 59 out of 70 (84.28%) in group A, compared to 41 out of 63 (65.07%) in group B (p=0.011). No significant difference between fertilization rates was found between the two study groups (p=0.702). The embryo development rate was higher in group A (33/59, 75%) than in group B (12/41, 42.85%; p=0.006). The proportion of highest-quality embryos and the blastocyst formation rate were significantly lower in group B than in group A (p=0.003 and p<0.001, respectively).

Conclusion

The findings of the current study demonstrate that culturing immature human oocytes with GCs prior to ICSI improves the maturation rate and the likelihood of embryo development.

The effect of vitrification on maturation and viability capacities of immature human oocytes

BACKGROUND

15 % of oocytes collected from Assisted Reproductive Technology (ART) cycles are immature. These oocytes may be matured following in vitro maturation (IVM) program. It is possible to cryopreserve the immature oocytes for further use in ART after application of IVM.

OBJECTIVE

The aim was to determine the maturation rate and viability of human oocytes that were matured in vitro after vitrification program.

MATERIALS AND METHODS

63 women (19-43 years old) who underwent controlled ovarian stimulation for ART were included in this study. 53 immature oocytes were used for fresh group (fIVM) and 50 immature oocytes for vitrification group (vIVM). The maturation medium was Ham's F10 supplemented with 0.75 IU FSH, 0.75 IU LH and 40 % human follicular fluid (HFF). After 36 h, maturation and morphology of all oocytes were assessed. Also, the oocyte viability was assessed using PI/Hoechst immunostaining technique.

RESULTS

The maturation rates were reduced in vIVM group (56.0 %) in comparison to fIVM group (88.7 %; P < 0.001). Oocyte viability rate were also reduced in vIVM group (56.0 %) in comparison to fIVM (86.8 %, P < 0.007).

CONCLUSIONS

Cryopreservation via vitrification reduced both the maturation capacity and viability of human oocytes in IVM technology. It is, therefore, recommended to apply IVM on fresh immature oocytes, instead.

The effect of human cumulus cells on the maturation and developmental potential of immature oocytes in ICSI cycles

PURPOSE

To investigate the effect of human cumulus cells on the maturation and developmental potential of immature oocytes in ICSI cycles.

METHODS

Immature oocytes were randomly divided into two groups: the cumulus-denuded oocyte group (group A) and the cumulus-intact oocyte group (group B). Only oocytes that reached metaphase II (MII) stage after in vitro maturation were used in the ICSI procedure. In vivo mature sibling MII oocytes served as the control group. Maturation rate, fertilization rate, embryo quality and developmental potential were examined.

RESULTS

There was no significant difference in maturation rate between group A (68.16%) and group B (70.49%; P > 0.05). The total fertilization rate among the three groups was comparable (P > 0.05), while the zygotes with two pronuclei in group A (74.59%) or group B (75.97%) were significantly lower than those in control group (84.29%; P < 0.05). The available embryo rate in group A (11.49%) was markedly lower than that in group B (27.66%; P < 0.05), and both of them were significantly lower than that in control group (62.38%; P < 0.05). The proportion of ≥6-cell embryos in group B (45.74%) was notably higher than in group A (26.44%; P < 0.05), and both were markedly lower than in control group (65.92%; P < 0.05). The proportion of embryos with <10% fragmentation in group A (13.79%) was significantly lower than in group B (29.79%; P < 0.05), and both were notably lower than in control group (42.98%; P < 0.05).

CONCLUSIONS

The presence of cumulus cells surrounding the immature oocytes during IVM before ICSI had no influence on nuclear maturation and fertilization, but leads to better subsequent embryonic development. This is perhaps mediated by an improvement in cytoplasmic maturation.

Healthy live birth from vitrified blastocysts produced from natural cycle IVF/IVM

Natural-cycle IVF combined with in-vitro maturation (natural-cycle IVF/IVM) was used as a treatment for a 27-year-old woman. She was administered 10,000 IU of human chorionic gonadotrophin intramuscularly about 36 h prior to oocyte collection and oocyte collection was performed on day 11 of her menstrual cycle. One mature oocyte was retrieved from the leading follicle and another five mature oocytes and six immature oocytes were retrieved from the rest of the follicles. Out of 10 fertilized zygotes, eight of them cleaved. Three day-3 embryos derived from in-vivo matured oocytes (one was from the leading follicle) were transferred but failed to conceive. The remaining five embryos were continuously cultured until day 6 and four of them developed to the expanded blastocyst stage and vitrified for the storage. Six months later, two vitrified-warmed blastocysts derived from the immature oocytes were transferred and resulted in the full-term delivery of a healthy female infant. This case report for the first time indicates that blastocysts produced from the immature oocytes retrieved from the small follicles, when a leading follicle exists in the ovaries, can be vitrified to produce a healthy live birth, suggesting that natural-cycle IVF/IVM is an efficient infertility treatment.

Selection of oocytes for in vitro maturation by brilliant cresyl blue staining: a study using the mouse model

Selecting oocytes that are most likely to develop is crucial for in vitro fertilization and animal cloning. Brilliant cresyl blue (BCB) staining has been used for oocyte selection in large animals, but its wider utility needs further evaluation. Mouse oocytes were divided into those stained (BCB+) and those unstained (BCB-) according to their ooplasm BCB coloration. Chromatin configurations, cumulus cell apoptosis, cytoplasmic maturity and developmental competence were compared between the BCB+ and BCB- oocytes. The effects of oocyte diameter, sexual maturity and gonadotropin stimulation on the competence of BCB+ oocytes were also analyzed. In the large- and medium-size groups, BCB+ oocytes were larger and showed more surrounded nucleoli (SN) chromatin configurations and higher frequencies of early atresia, and they also gained better cytoplasmic maturity (determined as the intracellular GSH level and pattern of mitochondrial distribution) and higher developmental potential after in vitro maturation (IVM) than the BCB- oocytes. Adult mice produced more BCB+ oocytes with higher competence than the prepubertal mice when not primed with PMSG. PMSG priming increased both proportion and developmental potency of BCB+ oocytes. The BCB+ oocytes in the large-size group showed more SN chromatin configurations, better cytoplasmic maturity and higher developmental potential than their counterparts in the medium-size group. It is concluded that BCB staining can be used as an efficient method for oocyte selection, but that the competence of the BCB+ oocytes may vary with oocyte diameter, animal sexual maturity and gonadotropin stimulation. Taken together, the series of criteria described here would allow for better choices in selecting oocytes for better development.

Poor responders in IVF: cancellation of a first cycle is not predictive of a subsequent failure

Management of women with a poor response to controlled ovarian hyperstimulation during IVF remains a frustrating challenge. The present study included 96 cycles from an equal number of women with a poor ovarian response and successful oocyte retrieval. Poor response was defined by the presence of at least one of the following characteristics: three or fewer oocytes on retrieval, serum estradiol level less than 500 pg/mL on the day of hCG administration, and serum FSH levels less than 20 IU/L. The same patients had a previous cycle cancelled because of a poor ovarian response whereas in the second cycle they preferred to continue the treatment despite the poor prognosis. We obtained 241 oocytes in the 96 IVF cycles. The fertilization rate was 60.2%. Three oocytes per cycle were retrieved in 56 cycles (58.3%), two oocytes per cycle in 33 cycles (34.4%), and one oocyte per cycle in 7 cycles (7.3%). In 19 cycles (19.8%) no fertilization was achieved. An embryo transfer was finally performed in 74 out of 96 cycles. Pregnancy rate was 12.5% per cycle and 16.2% per transfer. Among the 12 pregnancies achieved, 7 were in the 3-oocyte cycles and 5 in the 2-oocyte cycles. No pregnancies were achieved in the 1-oocyte cycles. Our data demonstrate that continuation of therapy in poor responders undergoing IVF can be an option despite the low pregnancy rates. The prognosis of these patients is not affected by a poor response in the first cycle and for some of them the outcome can be favorable.

Effects of in vitro maturation of monkey oocytes on their developmental capacity

The study of in vitro maturation (IVM) of rhesus monkey oocytes has important implications for biomedical research and human infertility treatment. In vitro-matured rhesus monkey oocytes show much less developmental potential than IVM oocytes of other species. Since about 1980 when rhesus monkey IVM, in vitro fertilization (IVF) and in vitro embryo culture (IVC) systems were established, numerous efforts have been made to improve the developmental competence of oocytes and to understand the mechanisms regulating oocyte maturation. This review describes recent progress in this area, particularly the effects of factors such as steroid hormones, energy substrates, amino acids, ovarian follicle status, maternal age and breeding season on the developmental competence, gene expression patterns and genome integrity of rhesus IVM oocytes.

In vitro maturation of human oocytes for assisted reproduction

OBJECTIVE

To describe and evaluate the current practice of in vitro maturation of oocytes for assisted reproduction.

DESIGN

Review of the available and relevant literature regarding in vitro maturation of oocytes.

CONCLUSION(S)

In vitro maturation of human oocytes retrieved from antral ovarian follicles is an emerging procedure quickly being incorporated into the realm of assisted reproductive technologies. This new technology has several potential advantages over traditional controlled ovarian hyperstimulation for IVF, such as reduction of costs by minimizing gonadotropin and GnRH analogue use, elimination of ovarian hyperstimulation syndrome, and simplicity of protocol. In vitro maturation of oocytes for assisted reproduction in human beings still is undergoing refinement but currently is providing efficacy and safety outcome comparable to that of traditional IVF in recent selected studies. Implementing in vitro maturation into an established IVF practice is feasible and requires only a few simple adjustments. Crucial to the advancement and optimization of the technology is a better understanding of how to maximize immature oocyte developmental competence and endometrial receptivity.

Fertilization, cleavage and blastocyst development according to the maturation timing of oocytes in in vitro maturation cycles*

BACKGROUND

This study was to examine the developmental capacity of oocytes collected from an in vitro maturation (IVM) programme according to their maturation time.

METHODS

The study included 47 IVM cycles that underwent blastocyst transfer. The patients (n = 38) were primed with 10 000 IU HCG 36 h before their oocyte retrieval. The oocytes were classified into three groups: group 1 (n = 139) where oocytes were matured on day of oocyte collection; group 2 (n = 627) where oocytes were matured on day 1 after IVM; group 3 (n = 163) where oocytes matured on day 2 after IVM. Fertilization, cleavage and blastocyst formation were compared between three groups.

RESULTS

Rates of cleavage and blastocyst development in group 3 (72.2%, 96/133; 19.0%, 15/133) were significantly lower than those of group 1 (100%, 108/108; 58.3%, 63/108) and group 2 (91.5%, 487/532; 50.4%, 268/532) respectively (P < 0.01). The number of freezable good quality blastocysts among blastocysts developed from group 1 (52.4%, 33/63) was significantly higher than those from group 2 (35.4%, 95/268) and group 3 (6.7%, 1/15) (P < 0.01). There were 24 clinical pregnancies (51.1%, 24/47) after transfer of the blastocysts and 29 healthy babies were delivered.

CONCLUSION

These results suggest that oocytes reaching metaphase II faster in an IVM programme have better embryonic developmental competence.

Correlation between in vitro maturation and expression of LH receptor in cumulus cells of the oocytes collected from PCOS patients in HCG-primed IVM cycles

BACKGROUND

The aim of this study was to investigate whether in vitro maturation (IVM) and blastocyst development of oocytes collected following HCG-primed IVM cycles of PCOS patients are correlated with their cumulus cell (CC) patterns and further to investigate mRNA expression of the receptors for FSH, LH and epidermal growth factor (EGF) in the CCs with each pattern.

METHODS

Patients who underwent IVM were primed with 10,000 IU of HCG 36 h before oocyte aspiration. The isolated cumulus-oocyte complexes were divided into three groups according to the CC patterns: oocytes with dispersed CCs (group A), oocytes with compacted CCs (group B) and oocytes with sparse CCs (group C). Oocyte maturation and blastocyst development were compared among three groups. The expression of the mRNA for FSH, LH and EGF receptors in group A and B was analysed by semi-quantitative RT-PCR.

RESULTS

The maturation rate of group A was significantly higher than those of group B and C. The rate of blastocysts in group A was significantly higher than those of group B and C. mRNA expression of the LH receptor in group A was more abundant than that of group B.

CONCLUSIONS

These results suggest that the presence of dispersed CCs at oocyte collection may be positively correlated with the rates of oocyte maturation and blastocysts in HCG-primed IVM cycles. In addition, the expression of LH receptor in CCs may be correlated with the CC pattern of oocytes at collection.

Correlation between human follicular diameter and oocyte outcomes in an ICSI program

PURPOSE

To determine the correlation between the follicular sizes and oocyte recovery, metaphase II oocyte recovery, fertilization rate and good embryo quality from mature and immature oocytes in an intracytoplasmic sperm injection (ICSI) program.

METHODS

991 follicles obtained from 72 ICSI cycles were classified into three groups according to their diameters as measured by transvaginal ultrasound including group A (< 10 mm), group B (10-14 mm), and group C (> 14 mm). All obtained oocytes were classified according to their nuclear maturation: germinal vesicle (GV), metaphase I (MI) and metaphase II (MII). Mature oocytes underwent ICSI while immature oocytes were further cultured until maturity before ICSI was performed. The rates of fertilization and good quality embryos at day 3 were evaluated.

RESULTS

A progressive and significant increase in the rates of oocyte recovery and MII oocyte recovery were observed from group A follicles compared to the other groups (p < 0.001). The fertilization rate of mature and in vitro matured oocytes, as well as the rate of good quality embryos showed a tendency to increase from group A to group C follicles, but not significantly. The corresponding fertilization rates were 78 and 55.3% (p < 0.001) for mature and in vitro matured oocytes, respectively.

CONCLUSION

Collection of oocytes from small follicles, especially with a mean diameter less than 10 mm, and in vitro maturation of immature oocytes before fertilization may allow the total number of good quality and transferable embryos to be increased.

In-vitro maturation of oocytes from unstimulated polycystic ovaries

In-vitro fertilization (IVF), an established treatment for infertility, may result in pregnancy and live-birth rates higher than following natural conception in fertile couples. However, IVF is associated with two major complications, namely, multiple pregnancy and ovarian hyperstimulation syndrome. The latter is a consequence of the ovarian stimulation required for IVF. Women with polycystic ovaries (PCO) are at increased risk of developing this complication. Ovarian stimulation is not required for in-vitro maturation (IVM) of immature oocytes. This approach is therefore both cheaper and safer than IVF, particularly for women with PCO. It has been found that the IVM pregnancy rate is correlated with the number of antral follicles present, the peak ovarian stromal blood flow velocity at the baseline ultrasound scan, the number of immature oocytes collected, absence of a dominant follicle at the time of immature oocyte retrieval, and endometrial thickness at embryo transfer. The indications for IVM at present would include women requiring IVF who have PCO, those with primarily poor quality embryos in repeated previous IVF cycles for no apparent reason, poor responders to high dose gonadotrophin stimulation for IVF, and finally, women with PCO who are considering egg donation.

Influence of the dominant follicle on in-vitro maturation of human oocytes: a prospective non-randomized study

The present study was designed to examine the influence of timing of aspiration and the influence of a dominant follicle on maturation and fertility potential of immature oocytes aspirated in unstimulated cycles. The study included 81 regularly cycling women. In group I (n = 53), oocyte retrieval was scheduled the day after a follicle of 10 mm and an endometrium of at least 5 mm were observed. In group II (n = 28), aspiration was scheduled the day after observation of the same ultrasound criteria plus a detected increase (100%) in the level of oestradiol compared with the level on day 3. The maturation rate was significantly higher in group I compared with group II (107/184, 58.2% versus 56/124, 45.2%, P < 0.05), whereas the rates of fertilization and cleavage did not differ between the two groups. The clinical pregnancy rate per aspiration was significantly higher in group I compared with group II (9/53, 17% versus 0/28, 0%, P < 0.05). When comparing oocytes originating from the ovary with the dominant follicle (ipsilateral ovary) with oocytes originating from the ovary without a dominant follicle (contralateral ovary) an increased fertilization rate was observed in group I, and an increased maturation rate was observed in group II. When the data from the two groups were pooled, an increased maturation rate was observed in oocytes originating from the ipsilateral ovary compared with oocytes originating from the contralateral ovary. No difference was found with respect to rates of fertilization and cleavage rates when all oocytes originating from the ipsilateral ovary were compared with all oocytes originating from the contralateral ovary.

Evaluation and treatment of low responders in assisted reproductive technology: a challenge to meet

PURPOSE

To investigate the various methods of evaluation and treatment of patients with a low response to controlled ovarian hyperstimulation in assisted reproductive technologies (ART).

METHODS

Review and analysis of relevant studies published in the last decade, identified through the literature and Medline searches.

RESULTS

While a universally accepted definition for low responders is still lacking, these patients are reported to represent about 10% of the ART population. Several ovarian reserve screening techniques have been proposed; however, currently the best-characterized and most sensitive screening tools available are the basal day 3 serum follicle-stimulating hormone level and the clomiphene citrate challenge test. When abnormal, these tests allow physicians to counsel patients that their prognosis for conception is poor. Although the presence of a normal result does indicate better long-term chances for conception, on age-related decline in fecundity remains and patient age should still be considered when counseling patients with normal screening results. Several stimulation protocols have been applied in the low-response group with varying success. Recent studies show that the use of a minidose gonadotropin-releasing hormone-agonist protocol may result in significantly decreased cycle cancellations as well as increased clinical and ongoing pregnancies, and thus is proposed as a first-line therapy. Studies evaluating supplementary forms of treatment to the ovulation induction regimen show improved outcome when pretreating with oral contraceptives, whereas there seems to be no benefit from cotreatment with growth hormone or glucocorticoids. Blastocyst culture and transfer and assisted hatching in low responders are still under evaluation, whereas natural cycle in vitro fertilization may be used in cases of repeated failures as a last option before resorting to oocyte donation or adoption. Future possible forms of treatment like in vitro maturation of immature human oocytes, cytoplasm, and nuclear transfer currently are experimental in nature and their efficacy has still to be proven.

CONCLUSIONS

The evaluation and treatment of low responders in ART remains a challenge. Understanding of the underlying etiology and pathophysiology of this disorder may help the clinician to approach it successfully.

In-vitro maturation of human oocytes from regularly menstruating women may be successful without follicle stimulating hormone priming

This prospective randomized study investigated whether the developmental potential of in-vitro matured (IVM) human oocytes is improved by follicle stimulating hormone (FSH) priming before aspiration. Normally cycling women were recruited among couples referred for in-vitro fertilization or intracytoplasmic sperm injection because of male factor and/or tubal disease. In the first experiment, 20 women were randomly allocated to either no stimulation (n = 10) or stimulation for 3 days with rec-FSH (Gonal-F, Serono) at a fixed dose of 150 IU/day from day 3 (n = 10). The oocytes were aspirated when the follicle(s) was observed to be 10 mm and matured in vitro for 36 h. In experiment 2, 12 women received rec-FSH (150 IU/daily) from day 3. In five patients stimulation was given for 3 days and aspiration performed as in the first experiment; the remaining seven patients continued stimulation until follicles were 10 mm in diameter and aspiration was performed 72 h later. All the oocytes were cultured for 48 h. FSH priming did not increase the number of oocytes obtained per aspiration and did not improve on maturation to metaphase II, cleavage rate or embryo development. The implantation potential of IVM embryos may be improved by maturation for 36 h compared to 48 h. In the first experiment, five out of 20 patients (25%) obtained a clinical pregnancy with an implantation rate of 15% (5/33). One has delivered a healthy boy and three pregnancies are ongoing beyond 32 gestational weeks. In the second experiment, an implantation rate of 7% and a single pregnancy (8%) was obtained, with delivery of a healthy girl.

In-vitro matured metaphase-I oocytes have a lower fertilization rate but similar embryo quality as mature metaphase-II oocytes after intracytoplasmic sperm injection

About 4% of all the oocytes denuded prior to intracytoplasmic sperm injection (ICSI) are in metaphase-I (MI). Frequently, these oocytes achieve meiosis after a few hours of in-vitro culture and are available for ICSI on the day of oocyte retrieval. In this retrospective study, the aim was to evaluate the fertilization rate and the developmental capacity of these in-vitro matured MI oocytes. After controlled ovarian stimulation using human menopausal gonadotrophin (HMG) and human chorionic gonadotrophin (HCG) in 896 ICSI cycles, 1210 MI-to-MII-matured oocytes were injected approximately 4 h after in-vitro culture and 8803 MII oocytes were injected immediately, or later, after denudation. The fertilization rate of in-vitro matured oocytes was significantly lower than that of mature MII oocytes (52.7 and 70.8% respectively, P < 0.00l). Embryo quality was only slightly different as regards the numbers of good quality embryos: 47.4% good quality embryos were obtained in the in-vitro matured oocyte group, whereas 53.2% good quality embryos were obtained in the MII oocyte group (P < 0.05). The same proportions of excellent (5.7 and 7.0%, NS) and fair quality (17.6 and 15.3%, NS) embryos were obtained for in-vitro matured and mature oocytes respectively. Embryos derived from in-vitro matured oocytes were transferred only if they were of better quality or if there were not enough mature oocyte derived embryos available. Fifteen transfers involved only embryos derived from in-vitro matured oocytes: 11 single embryo transfers and four transfers of two embryos, resulting in one singleton pregnancy and the birth of a healthy baby. It may be concluded that in cycles with few MII oocytes it might be worthwhile to inject in-vitro matured MI oocytes in order to increase the number of embryos available for transfer.

Immature oocyte retrieval with in-vitro oocyte maturation

Early studies of in-vitro fertilization used immature oocytes. The process evolved to retrieving metaphase II oocytes, and was eventually successful. At present, aggressive ovulation induction protocols are the mainstay of assisted reproductive technology programs, but not without increased cost, multiple gestations, morbidity, potential future risks and isolated mortalities. The ability to retrieve each month's cohort of immature oocytes transvaginally opened the door to search for a new option for infertile couples requiring assisted reproductive technology. Immature oocyte retrieval combined with in-vitro oocyte maturation eliminates the stimulation, costs and time that were required to monitor oocytes, along with the short- and long-term complications. The essential components are optimal maturation media and a synchronized endometrium in which the embryos transferred from a truncated follicular phase can implant. The process has been successful in several centers with an acceptable success rate when used in conjunction with a host uterus. Future research with maturation, culture, and endometrial synchronization may allow immature oocyte retrieval with in-vitro oocyte maturation to replace in-vitro fertilization in its present form.