Relationship of the human cumulus-free oocyte maturational profile with in vitro outcome parameters after intracytoplasmic sperm injection

The developmental competence of human metaphase I oocytes with delayed maturation in vitro

OBJECTIVE

To evaluate whether metaphase I (MI) oocytes completing maturation in vitro to metaphase II ("MI-MII oocytes") have similar developmental competence as the sibling metaphase II (MII) oocytes that reached maturity in vivo.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center.

PATIENT(S)

A total of 1,124 intracytoplasmic sperm injection (ICSI) cycles from 800 patients at a single academic center between April 2016 and December 2020 with at least 1 MII oocyte immediately after retrieval and at least 1 sibling "MI-MII oocyte" that was retrieved as MI and matured to MII in culture before ICSI were included in the study.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

A total of 7,865 MII and 2,369 sibling MI-MII oocytes retrieved from the same individuals were compared for the fertilization and blastocyst formation rates. For patients who underwent single euploid blastocyst transfers (n = 406), the clinical pregnancy, spontaneous pregnancy loss, and live birth rates were compared between the 2 groups.

RESULT(S)

The fertilization rate was significantly higher in MII oocytes than in delayed matured MI-MII oocytes (75.9% vs. 56.1%). Similarly, the blastocyst formation rate was higher in embryos derived from MII oocytes than in those from MI-MII oocytes (53.8% vs. 23.9%). The percentage of euploid embryos derived from MII oocytes was significantly higher than that of those from MI-MII oocytes (49.2% vs. 34.7%). Paired comparison of sibling oocytes within the same cycle showed higher developmental competence of the MII oocytes than that of MI-MII oocytes. However, the pregnancy, spontaneous pregnancy loss, and live birth rates after a single euploid blastocyst transfer showed no statistically significant difference between the 2 groups (MII vs. MI-MII group, 65.7% vs. 74.1%, 6.4% vs. 5.0%, and 61.5% vs. 70.0%, respectively).

CONCLUSION(S)

Compared with oocytes that matured in vivo and were retrieved as MII, the oocytes that were retrieved as MI and matured to MII in vitro before ICSI showed lower developmental competence, including lower fertilization, blastocyst formation, and euploidy rates. However, euploid blastocysts from either cohort resulted in similar live birth rates, indicating that the MI oocytes with delayed maturation can still be useful even though the overall developmental competence was lower than that of their in vivo matured counterparts.

Developmental potential of immature human oocytes aspirated after controlled ovarian stimulation

PURPOSE

Intracytoplasmic sperm injection (ICSI) for initially immature oocytes that mature in vitro is controversial and practice varies widely. While it may increase the number of usable embryos, it may also be time-intensive and potentially low-yield. This study sought to elucidate which patients may benefit from ICSI of initially immature oocytes that matured in vitro.

METHODS

A retrospective study comparing fertilization, cleavage, blastulation, and embryo usage rates between sibling initially immature and mature oocytes that underwent ICSI between 2015 and 2019 was performed. Outcomes of initially immature oocytes were stratified by initial maturation stage, timing of progression to metaphase II (MII) in vitro, percentage of mature oocytes in the cycle, and female age.

RESULTS

Ten thousand eight hundred seventeen oocytes from 889 cycles were included. Of 3137 (29.0%) initially immature oocytes, 418 (13.3%) reached MII later on the day of retrieval (day 0) and 1493 (47.6%) on day 1. Overall, embryos originating from initially immature oocytes had lower cleavage and blastulation rates compared to those from initially mature oocytes (P<0.05, all groups). However, embryos from oocytes that matured later on day 0 comprised a unique subset that had clinically similar cleavage (75% vs 80%, RR 0.93, P=0.047) and blastulation rates (41% vs 50%, RR 0.81, P=0.024) compared to initially mature oocytes. Women with low percentages of mature oocytes in the cycle overall and women ≥40 in cleavage cycles derived the highest relative benefit from the use of immature oocytes.

CONCLUSION

ICSI of immature oocytes, particularly those that mature later on the day of retrieval, may improve numbers of usable embryos. This study supports routine reassessment of immature oocytes for progression to MII and ICSI on day 0. An additional reassessment on day 1 may also be of use in older women or those with low percentage of mature oocytes.

The Effect of Human Chorionic Gonadotropin on the In vitro Development of Immature to Mature Human Oocytes: A Randomized Controlled Study

Context

In controlled ovarian hyperstimulation cycles, 15% of oocytes have been proven to be immature. Key factors include failure in signal transmission from the cumulus cell to the oocyte, insufficient level of luteinizing hormone, and internal conditions of the oocyte itself.

Aims

The aim of the present study was to investigate the effect of human chorionic gonadotropin (hCG) on the in vitro maturity of partially cumulus-denuded immature oocytes collected after controlled ovarian stimulation for in vitro fertilization (IVF).

Settings and Design

This was a prospective, randomized controlled design at the department of obstetrics and gynaecology, university hospital.

Subjects and Methods

Infertile women underwent gonadotropin-releasing hormone antagonist stimulated protocol for IVF with final maturation triggered by hCG, partially cumulus-denuded immature human oocytes were allocated to two groups: the first was treated with fertilization medium and the second was treated with fertilization medium and hCG. They were cultured for 24 h. Outcomes measured were the oocyte maturation rates to metaphase II (MII) and glucose-6-phosphate dehydrogenase (G6PD) activity of in vitro maturation (IVM) mature oocytes which represent the oocyte quality.

Statistical Analysis Used

The Mann-Whitney U-test and One-way ANOVA were used to compare continuous variables, and Chi-square was used for categorical data.

Results

In all, 250 immature stimulated oocytes were allocated (125 per group). The maturation rate was higher in the hCG supplement group (48% vs. 39.2%) without significance. The positive brilliant cresyl blue results among the MII oocytes developed from the metaphase I (MI) were significantly higher in the hCG group (P = 0.001).

Conclusions

Rescue IVM in fertilization culture medium plus hCG was slightly better than that in the only fertilization culture. MII oocytes developed from MI in hCG supplemented medium had a higher quality based on the measured G6PD activity.

Factors associated with extremely high progesterone concentrations on the day of HCG administration

OBJECTIVE

Progesterone elevation on the day of human chorionic gonadotropin (hCG) administration remains one of the most controversial topics in reproductive endocrinology. Factors associated with these increases have not been fully determined. The purpose of our study is to investigate factors associated with extreme progesterone elevation on the day of human chorionic gonadotropin (hCG) administration.

MATERIALS AND METHODS

This retrospective observational, single-center cohort study recruited 2000 fresh in vitro fertilization (IVF) and/or intracytoplasmic sperm injection(ICSI)-embryo transfer cycles from January 2000 to December 2014 in our institution.

RESULTS

When cycles were divided into those with progesterone <1.94 ng/mL (n = 1791) and ≧1.94 ng/mL (n = 209) on the day of hCG administration, five factors were positively associated with highly elevated progesterone concentration: protocol (GnRH agonist versus antagonist; odds ratio [OR = 2.786]), number of dominant follicles (OR = 1.098), total dose of follicle stimulating hormone (FSH) used (OR = 1.023), elevated luteinizing hormone (LH) (OR = 1.085) and estradiol (E2; OR = 1.001) concentrations on the day of hCG administration (p < 0.001 each). After omitting the protocol effect, the remaining factors showed limited contributions to highly elevated progesterone (ORs = 0.95-1.2).

CONCLUSIONS

The factor showing the greatest association with extreme progesterone elevation was use of the GnRH agonist protocol.

Fertilisation and early embryonic development of immature and rescue in vitro-matured sibling oocytes

The objective of this study was to assess the effect of rescue in vitro maturation and immediate intracytoplasmic sperm injection (ICSI) application on fertilisation success and early embryonic development of metaphase I (MI) oocytes. This was a retrospective cohort study including 2425 sibling oocytes in 259 ICSI cycles. ICSI was performed on 104 GV (germinal vesicle) oocytes which had reached the metaphase II (MII) stage (Group 1) and 231 MI oocytes which had reached the MII stage (Group 2) following IVM (in vitro maturation). Immediate ICSI was applied following oocyte aspiration on 292 MI stage (Group 3) and 1798 MII stage oocytes (Group 4). Normal fertilisation rates in Groups 1, 2, 3 and 4 were 51.9%, 39%, 30.1% and 59.5%, respectively. The rates of blastocyst development per oocyte and per zygote were calculated as 3.8%, 3.0%, 6.8%, 14.1% and 7.4%, 7.7%, 22.7%, 23.6% for Groups 1, 2, 3 and 4, respectively. The blastocyst development rate was significantly higher in the MI-ICSI group compared with other immature oocytes. Even though performing ICSI on the oocytes at the MI stage on the day of oocyte aspiration resulted in lower fertilisation rates, it was associated with significantly higher rates of blastocyst development.

Impact of sperm DNA fragmentation on ICSI outcome and incidence of apoptosis of human pre-implantation embryos obtained from in vitro matured MII oocytes

BACKGROUND

Sperm DNA integrity and oocyte quality significantly affect embryo development and survival. The current study evaluated embryo development and quality, as well as the expression level of apoptosis-related genes and microRNAs in embryo derived from in vitro matured MII oocytes according to sperm DNA fragmentation (SDF) level.

METHODS

The semen and immature oocytes were collected from 50 ICSI cycles with any recognizable female factor infertility. After ovarian stimulation, germinal vesicle stage (GV) oocytes were collected and incubated in in vitro maturation (IVM) medium for 24 h. Next, reactive oxygen species (ROS) level of media culture was determined. Using by sperm chromatin dispersion (SCD) test, the SDF levels of processed semen were assessed and categorized into SDF ≤ 30% and SDF>30%. Seventy two hours after intracytoplasmic injection, the embryo development and quality score were recorded in the groups I (GV-MII + SDF≤ 30%) and II (GV-MII + SDF> 30%). Also, the apoptosis incidence of embryos at morula stage was evaluated at molecular and cellular levels by quantitative real time PCR and TUNEL staining, respectively.

RESULTS

Cleavage rate did not differ between two groups. The quality score of embryos obtained from IVM matured oocytes and high level of SDF was significantly lower than that of low level of SDF (P < 0.05). The embryos from group II had a significant reduction of the expression of BCL-2 compared to group I (P < 0.05). Also, they showed an increase in relative transcription of pro-apoptotic microRNAs; miR 15a and miR 16-1 versus group I (P < 0.05). A rise of TUNEL positive blastomers of embryo was observed at group II versus group I, but it did not reach to significantly level.

CONCLUSION

The IVM oocytes, probably, did not suffice to recover the high level of paternal genomic damage and inhibition of apoptosis pathway beginning.

Strategies to improve fertilisation rates with assisted conception: a systematic review

Successful fertilisation is one of the key steps determining success of assisted conception. Various factors including sperm or oocyte pathology and environmental factors have a significant impact on fertilisation rates. This systematic review is aimed to evaluate the existing evidence about factors affecting fertilisation and strategies to improve fertilisation rates. A literature search was performed using Ovid MEDLINE ® (Jan 1950-April 2016), EMBASE (Jan 1950-April 2016), Ovid OLDMEDLINE ®, Pre-MEDLINE (Jan 1950-April 2016) and the Cochrane Library. Relevant key words were used to combine sets of results and a total 243 papers were screened. Only qualitative analysis was performed, as there was major heterogeneity in study design and methodology for quantitative synthesis. Factors affecting fertilisation were divided into sperm- and oocyte-related factors. The methods to improve fertilisation rates were grouped together based on the approach used to improve fertilisation rates. Optimising laboratory condition and procedural effects in techniques is associated with improved fertilisation rates. Various techniques are described to improve fertilisation rates including assisted oocyte activation, physiological intracytoplasmic sperm injection (PICSI) and intracytoplasmic morphologically selected sperm injection (IMSI). This review highlights the promising strategies under research to enhance fertilisation rates. Adequately powered multicentre randomised trials are required to evaluate these techniques before considering clinical application.

DECREASED FERTILIZATION: HUMAN SPERM DNA FRAGMENTATION AND IN VITRO MATURATION OF OOCYTE IN STIMULATED ICSI CYCLES

Objective

The aim of this study was to evaluate the impact of sperm DNA fragmentation (SDF) on fertilization rate, and sperm nuclear decondensation after intracytoplasmic injection of sperm (ICSI) into cumulus-free germinal vesicle (GV) oocytes from stimulated cycles.

Methods and study design

After the retrieval of oocytes, the GV oocytes were cultured for 24 h. Oocytes that liberated polar bodies were injected with processed semen, and were used to evaluate SDF level. Based on SDF, the data were categorized into two groups. Group I in which SDF≤ 30% and group II in which SDF > 30%. Fertilization (presence of two pronuclei) was checked 16-19 h after ICSI. Unfertilized oocytes were stained by Hoechst 33258 and examined to evaluate the undecondensed sperm head in oocyte. The rates of maturation, fertilization in fertilized IVM oocytes and the percentage of undecondensed sperm in the unfertilized oocytes were assessed according to SDF.

Results

Out of 146 GV oocytes that were subjected to IVM, 101 (69 %) developed to metaphase II. The fertilization rate of IVM oocytes in group II was significantly lower than that in group I (P < 0.05). Moreover, group I, had 25 % of their unfertilized oocytes containing condensed sperm, while group II had a significantly higher number (53 %) of unfertilized oocytes containing condensed sperm (P < 0.05).

Conclusion

SDF had a negative effect on the rate of fertilization in matured in vitro GV oocytes and could lead to an increase in the percentage of undecondensed sperm in IVM oocytes from stimulated cycles.

Rescue in vitro maturation (IVM) of immature oocytes in stimulated cycles in women with low functional ovarian reserve (LFOR)

Rescue in vitro maturation (IVM) is currently not a routine procedure in association with in vitro fertilization (IVF). We compared in a prospectively cohort study of 10 patients with normal functional ovarian reserve (NFOR) and of 25 with low functional ovarian reserve (LFOR), defined by abnormally high FSH and/or abnormally low AMH levels), IVM dynamics of immature oocytes. Following controlled ovarian hyperstimulation in IVF cycles, only immature oocytes underwent rescue IVM (for up to 48 h). Oocyte maturation dynamics, fertilization rates, embryo development, and pregnancy rates were then compared between NFOR and LFOR patients. Though proportion of MI and GV oocytes reaching MII stages within 48 h and rate of maturation of MI oocytes did not differ, in women with LFOR significantly more GV oocytes reached MII stage within 24 h (30.4 vs. 66.9 %; P = 0.013), while fertilization rates and embryo generation numbers were similar between both groups. Rescue IVM, thus, produced 1.5 additional embryos for transfer in women with LFOR and 1.6 in patients with NFOR, a highly significant difference in relative improvement in available embryo numbers for LFOR (+60.0 %) and NFOR women (+16.5 %). Rescue IVM, thus, not only demonstrates different time dynamics between women with LFOR and NFOR but also disproportionate efficacy in improving available embryo numbers for transfer in favor of LFOR patients. 1/7 patients, who reached embryo transfer with only embryos produced via rescue IVF conceived and delivered, proving that rescue IVF in women with LFOR also improves pregnancy and delivery chances. Because of the small number of embryos LFOR patients produce, every additional embryo is of considerable potential clinical significance for them, suggesting that rescue IVM in women with LFOR should become routine practice.

Conventional in vitro fertilization maybe yields more available embryos than intracytoplasmic sperm injection for patients with no indications for ICSI

Many physicians suggest that performing ICSI instead of IVF for all cases just because they thought that ICSI yields more available embryos than IVF. However, we found that IVF results in better fertilization per retrieved oocyte (72.12 ± 19.60% versus 59.54 ± 21.38%, P < 0.01) and day 3 available embryo per retrieved oocyte rates (54.89 ± 23.53% versus 50.54 ± 22.68%, P < 0.05) than ICSI after analysis of 218 cycles using sibling oocytes in combined IVF/ICSI for patients with no indications for ICSI. We also found a positive correlation between the degeneration rate after ICSI, oocyte immaturity rate, and rate of 2 pn per retrieved oocyte obtained from IVF compared to ICSI, as well as the day 3 available embryo rate between IVF and ICSI. It is possible that outcome may be due to more in vitro-matured oocytes achieved in IVF fertilization compared with ICSI fertilization, and a considerable portion of the mature oocytes were degenerated after ICSI. Therefore, it is suggested that ICSI should not be performed in all cases of in vitro conception. IVF is preferable to ICSI for cases in which a relatively low possible fertilization failure occurs in conventional IVF.

Pregnancy and fertilization potential of immature oocytes retrieved in intracytoplasmic sperm injection cycles

OBJECTIVE

The goal of this study was to evaluate the pregnancy potential of immature (metaphase I or germinal vesicle stage) oocytes retrieved in intracytoplasmic sperm injection (ICSI) cycles.

METHODS

A total of 1,871 couples with infertility underwent 2,984 ICSI cycles. Cycles in which three or fewer oocytes were retrieved were included in this study in order to evaluate the pregnancy potential of immature oocytes. Cycles were divided into five groups (group I-V), according to the maturation status of the oocytes at the time of cumulus cell removal and ICSI. The fertilization and pregnancy rates after ICSI were analyzed and compared among the study groups based on the maturation status of the retrieved oocytes.

RESULTS

The retrieval of only immature oocytes was associated with a significant decrease in the fertilization rate (76.1%±37.3% vs. 49.0%±49.1%, 66.7%±48.7%; group I vs. group II, group III, respectively) and the average number of transferred embryos (1.5±0.7 vs. 1.1±0.4, 1.1±0.6). The cycle cancellation rate was significantly higher when only immature oocytes were retrieved. The clinical pregnancy rate decreased significantly when the transferred embryos had originated from immature oocytes (16.9% vs. 10.3%, 1.2%).

CONCLUSION

In ICSI cycles, the fertilization potential and pregnancy potential of the immature oocytes retrieved in ICSI cycles were inferior to those of mature oocytes. Therefore, increasing the number of injectable oocytes and transferrable embryos by using immature oocytes after their spontaneous in vitro maturation does not necessarily improve pregnancy outcomes.

The circadian Clock gene regulates acrosin activity of sperm through serine protease inhibitor A3K

Our previous study found that CLOCK knockdown in the testes of male mice led to a reduced fertility, which might be associated with the lower acrosin activity. In this present study, we examined the differential expression in proteins of CLOCK knockdown sperm. Clock gene expression was knocked down in cells to confirm those differentially expressions and serine protease inhibitor SERPINA3K was identified as a potential target. The up-regulated SERPINA3K revealed an inverse relationship with Clock knockdown. Direct treatment of normal sperm with recombinant SERPINA3K protein inhibited the acrosin activity and reduced in vitro fertilization rate. The luciferase reporter gene assay showed that the down-regulated of Clock gene could activate the Serpina3k promoter, but this activation was not affected by the mutation of E-box core sequence. Co-IP demonstrated a natural interaction between SERPIAN3K and RORs (α and β). Taken together, these results demonstrated that SERPINA3K is involved in the Clock gene-mediated male fertility by regulating acrosin activity and provide the first evidence that SERPINA3K could be regulated by Clock gene via retinoic acid-related orphan receptor response elements.

In vitro embryos production after oocytes treatment with forskolin

The inhibition of nuclear maturation allows time for the oocyte to accumulate molecules that are important for embryonic development. Thus, the objective of this work was to evaluate the effect of blocking oocyte meiosis with the addition of forskolin, an efficient inhibitor of nuclear maturation, in in vitro maturation (IVM) medium. Forskolin was added to the IVM medium for 6 h at concentrations of 0.1 mM, 0.05 mM or 0.025 mM, then the oocytes were allowed to mature in drug-free medium for 18 h. The oocytes were assessed for the stage of nuclear maturation, the activity and distribution of mitochondria, oocyte ultrastructure, the number of viable cells and the apoptosis rate. After forskolin treatment, the oocytes were fertilized in vitro and cultured for 7 days. On day 7, the blastocyst rate, the ultrastructure, the number of intact cells and the apoptosis rate of the blastocysts were measured. No differences were observed for the stage of nuclear maturation of the oocyte, the mitochondrial activity and distribution, the blastocyst rate or total number of intact cells. However, a higher rate of apoptosis was observed in the blastocysts produced from oocytes blocked for 6 h with the higher concentration of forskolin (P < 0.05). We conclude that all the experimental groups reached the MII stage after the addition of forskolin and that the highest concentration of forskolin caused cellular degeneration without harming embryo production on the 7th day.

Pregnancy outcome and neonatal data of children born after intracytoplasmic sperm injection with a different duration of cryopreservation of spermatozoa obtained through testicular sperm extraction

OBJECTIVE

To evaluate the impact of the duration of cryopreservation of testicular sperm on clinical and neonatal outcomes after intracytoplasmic sperm injection (ICSI) for patients experiencing azoospermia.

MATERIALS AND METHODS

This study included 132 azoospermic men who participated in 212 ICSI cycles. The participating men underwent testicular biopsy for the cryopreservation of tissue to be used for subsequent ICSI cycles. The duration of the storage of testicular sperm was determined by the time of oocyte retrieval. Fertilization, embryo development in vitro, pregnancy rates, and neonatal outcomes were assessed.

RESULTS

Although the mean percentage of viability decreased from 73.2% prior to freezing to 50.2% after thawing, viable spermatozoa were visualized subsequent to thawing of the tissue samples for all patients. The potential for fertilization and subsequent embryonic development was not influenced by the duration of sperm cryopreservation up to 2 years longer. The pregnancy outcomes also varied independently of the duration of sperm cryopreservation. The duration of storage did not appear to affect the neonatal outcomes adversely, including the Apgar score and intensive care unit admission rates, although neonatal outcomes were influenced by advanced maternal age. It also has no obvious impact on the major and minor congenital malformation rate of the newborns.

CONCLUSION

ICSI outcomes, pregnancy outcome, neonatal outcome, and congenital malformation rate appear not to be affected by the duration of the period of cryostorage. An earlier start of the ICSI cycle following the testicular sperm cryopreservation is preferable because longer preservation is associated with more advanced maternal age.

The Noncircadian Function of the Circadian Clock Gene in the Regulation of Male Fertility

Mice homozygous for a dominant-negative allele of the Clock gene ( ClockΔ 19/Δ 19) have slightly but significantly decreased male fertility. The molecular mechanism for this reduction in fertility is unknown. In the present study, we used a small hairpin RNA (shRNA) strategy to specifically knock down the Clock gene expression in the testes of male mice and determined its effect on male fertility. Clock knockdown led to smaller litter size, a lower in vitro fertility rate, lower blastula formation rate, and lower acrosin activity of the knockdown sperm. Locomotor activity analysis of the Clock knockdown mice revealed that Clock knockdown in testes did not alter their circadian rhythm. Taken together, these results provide the first evidence that Clock gene expression in round spermatids is essential for maintaining male reproductivity and suggest that acrosin may be a novel regulatory target of the Clock gene that would regulate the fertilization and early embryonic development to blastula. These findings may provide new clues for development of novel male contraceptive strategies.

Fertilization and pregnancy potential of immature oocytes from stimulated intracytoplasmic sperm injection cycles

OBJECTIVE

We evaluated the fertilization potential of immature oocytes obtained from controlled ovarian hyperstimulation cycles of patients undergoing ICSI.

METHODS

We retrospectively analyzed 463 ICSI cycles containing at least one immature oocyte at oocyte denudation. ICSI was performed on mature oocytes at oocyte denudation (metaphase-II [MII] oocytes) and the oocytes that extruded the first polar body between oocyte denudation and ICSI (MI-MII oocytes). Fertilization and early embryonic development were compared between MII and MI-MII oocytes. To investigate the pregnancy potential of MI-MII oocytes, the pregnancy outcome was analyzed in 24 ICSI cycles containing only immature oocytes at retrieval.

RESULTS

The fertilization rate of MI-MII oocytes (37.0%) was significantly lower than that of MII oocytes (72.3%). The rates of delayed embryos and damaged embryos did not significantly differ. Eighty-one immature oocytes were retrieved in 24 cycles that retrieved only immature oocytes and 61 (75.3%) of them were in the MI stage. ICSI was performed on 36 oocytes (59.0%) that extruded the first polar body before ICSI and nine MI-MII oocytes (25.0%) were fertilized. Embryo transfers were performed in five cycles. Pregnancy was observed in one cycle, but it ended in biochemical pregnancy.

CONCLUSION

In ICSI cycles, oocytes that extruded the first polar body between denudation and ICSI can be used as a source of oocytes for sperm injection. However, their fertilization and pregnancy potential are lower than that of mature oocytes. Therefore, ovarian stimulation should be performed carefully for mature oocytes obtained at retrieval, especially in cycles with a small number of retrieved oocytes.

In vitro maturation, fertilization, embryo development & clinical outcome of human metaphase-I oocytes retrieved from stimulated intracytoplasmic sperm injection cycles

BACKGROUND & OBJECTIVES

The major cause of fertilisation failure after ICSI is failure of the oocyte to initiate the biochemical processes necessary for activation. This inability could be ascribed to cytoplasmic immaturity of those gametes even if they had reached nuclear maturity. The activation of a mature oocyte is characterised by release from metaphase II (MII) arrest and extrusion of the second polar body, followed by pro-nuclear formation. The aim of this study was to evaluate the fate of in vitro matured (IVM) metaphase I (MI) oocytes subjected to intracytoplasmic sperm injection (ICSI) at different time intervals after extrusion of the first polar body (1PB) in in vitro fertilization (IVF) cycles.

METHODS

A total of 8030 oocytes were collected from 1400 ICSI cycles, 5504 MII at the time of cumulus retrieval. Four hundred eight metaphase II (MII) (27.1%) matured to MII after in vitro culture for 2-26 h and 5389 sibling MII in the moment of oocyte denudation were injected. On the other hand, 49 ICSI cycles containing only MI oocytes at retrieval were injected at three different time intervals after reaching the MII. The intervals were as follows: 2-6 h (n=10), 8-11 h (n=4) and 23-26 h (n=10). Fertilization and development potential were evaluated in both studies.

RESULTS

Fertilization, embryo cleavage and quality were significantly lower in IVM MI compared to MII at time of denudation. Pregnancy rate was higher in group MII. Pregnancy was achieved in three embryo transfers when ICSI was performed within 2-6 h (group I) and 8-11 h (group II) after PB extrusion. One pregnancy was obtained in group I and a healthy neonate was born.

INTERPRETATION & CONCLUSIONS

Immature oocytes from women whose ovaries have been stimulated could be matured, fertilized by ICSI, cleaved in vitro and to give rise to a live birth. However, the developmental competence of embryos derived from immature oocytes is reduced, compared with sibling in vivo matured oocytes. Further, human IVM oocytes need between 2-6h after the 1PB extrusion to complete its maturation.

The dynamics of in vitro maturation of germinal vesicle oocytes

OBJECTIVE

To evaluate the dynamics of the nuclear maturation (NM) of in vitro-matured (IVM) oocytes and to determine the most favorable duration of meiosis II (MII) arrest in relation to the normal activation response.

DESIGN

Experimental.

SETTING

University-affiliated infertility clinic.

PATIENT(S)

Donated immature germinal vesicle oocytes (GV).

INTERVENTION(S)

The GV underwent spontaneous IVM and the dynamics of NM studied by real-time monitoring. The IVM oocytes were parthenogenetically activated at different MII arrest points and their response assessed.

MAIN OUTCOME MEASURE(S)

Moment of GV breakdown; extrusion of the first polar body; duration of MI and MII arrest; activation rate (AR) and type.

RESULT(S)

Two GV populations-early (E-IVM, 18.4 ± 2.7 hours) and late (L-IVM, 26.3 ± 3.8 hours) maturing-were defined according to the time required for extrusion of the first polar body. Significantly more E-IVM than L-IVM exhibited a normal activation response (61.3% vs. 34.6%), but AR were similar (average, 88.6%) in both groups. Duration of the GV stage differed between the two groups, but MI arrest (14.0 ± 0.3 hours) was constant. The E-IVM arrested at MII for at least 4.3 hours displayed significantly lower AR and similar normal activation rates (61.3%) to E-IVM arrested for a shorter time (83.9% vs. 100%). The L-IVM displayed a similar AR (80.8%), but lower normal activation rates than E-IVM (34.6%), regardless of when activation took place.

CONCLUSION(S)

The success of IVM depends on the NM timing rather than on the length of MII arrest.

In vitro maturation of cumulus-partially enclosed immature human oocytes by priming with gonadotropin

OBJECTIVE

To investigate the effect(s) of exogenous gonadotropin on the cytoplasmic and nuclear maturation of cumulus-partially enclosed immature human oocytes in vitro derived from ovarian stimulation cycles.

DESIGN

Experimental human study.

SETTING

University-based laboratory.

PATIENT(S)

Women, aged 26-35 years, with infertility secondary to male factors, underwent ovarian stimulation and intracytoplasmic sperm injection cycles using a long protocol of pituitary down-regulation.

INTERVENTION(S)

Cumulus-partially enclosed immature human oocytes that were retrieved from the stimulated cycles were collected at the time of intracytoplasmic sperm injection. The cumulus-partially enclosed immature human oocytes were allocated into two groups: [1] oocytes at the germinal vesicle (GV) stage; and [2] oocytes at the metaphase I (MI) stage. Each group was cultured in vitro with and without gonadotropin supplements. Some metaphase II (MII) oocytes derived from the two groups were parthenogenetically activated and exposed to subsequent embryonic development for 168 hours in vitro. Other MII oocytes were tested for meiotic apparatus analysis, including spindle morphology and chromosomal alignment, by immunofluorescence staining and scanning confocal microscopy.

MAIN OUTCOME MEASURE(S)

Oocyte maturation and activation rates, percentages of embryonic development, and spindle normalization were analyzed by χ(2) analysis, whereas oocyte maturation time was analyzed by one-way analysis of variance.

RESULT(S)

For GV oocytes the maturation and activation rates were significantly higher during in vitro maturation with supplementation with FSH/LH (68% vs. 60% and 82% vs. 62%, respectively). However, maturation time (22.78 ± 0.87 vs. 23.70 ± 0.94 hours), embryonic development (cleavage: 84% vs. 83%; four-cell: 72% vs. 66%; eight-cell: 48% vs. 43%; blastocyst: 5% vs. 7%), and meiotic apparatus normalization rates (55% vs. 61.1%) were similar. For MI oocytes there were no significant differences in the maturation rates (85% vs. 84%), maturation time (14.81 ± 0.65 vs.15.73 ± 0.58 hours), activation rates (77% vs. 80%), embryonic development (cleavage rates: 80% vs. 83%; four-cell: 68% vs. 72%; eight-cell: 56% vs. 51%; blastocyst: 7% vs. 6%), and meiotic apparatus normalization rates (52.4% vs. 54.5%). CONLUSION(S): Gonadotropin supplements to the maturation medium play an important role in cumulus-partially enclosed oocytes at the GV stage; however, MI stage-derived oocytes from stimulated cycles fail to acquire improved maturity after in vitro maturation. Furthermore, gonadotropin at the current concentration did not increase spindle or chromosomal abnormalities in MII oocytes maturated from either GV- or MI-stage oocytes in vitro.

Does the duration of gonadotropin stımulation affect embryo quality on post-retrieval day 3?

AIM

To determine if the duration of ovarian hyperstimulation affects quality of embryos on the 3rd day.

METHODS

Retrospective cohort study was designed in a University affiliated hospital. Six-hundred fifteen women undergoing first IVF treatment were grouped according to the duration of controlled ovarian hyperstimulation (COH) in long-down regulated cycles. Group A consisted of women with 8 or less days of COH, Group B consisted of women who had between 9 and 10 days of COH and Group C had 11 days or more COH. The degree of fragmentation and asymmetry of blastomeres were compared for the 3rd day after oocyte retrieval.

RESULTS

On day 3, there were more embryos with 10-25% fragmentation in Group A than in Group B. Embryos were also less symmetrical in Group A than in Group B.

CONCLUSIONS

COH cycles which are shorter than 9 days result in more embryos with more than 10% fragmentation on post-retrieval day 3.

Evaluation of the developmental potential of metaphase I oocytes from stimulated intracytoplasmic sperm injection cycles

The objective of the present study was to evaluate the developmental potential and clinical application value of metaphase I (MI) oocytes obtained from stimulated intracytoplasmic sperm injection (ICSI) cycles. ICSI was performed on MI oocytes immediately after denudation (Group A), or on in vitro-matured (IVM) oocytes following culture; oocytes in culture were further divided into two groups, being cultured for either 3–5 h (Group B) or 24–28 h (Group C). Metaphase II oocytes from the same cycle(s) isolated for ICSI served as the control group (Group D). The rates of normal fertilisation, cleavage and high-quality embryos were compared among the four groups. High-quality embryos were transferred whenever possible, and pregnancy rates were evaluated. Results showed that normal fertilisation rates for Groups B, C and D were significantly higher than that of Group A (68.6%, 57.8%, 74.5% and 30.1%, respectively; P < 0.01). The rate of high-quality embryos in Group B was comparable with Group D; the rate for Group C was significantly lower than that of the other groups (P < 0.05). Two clinical pregnancies were achieved after transfer of embryos from IVM oocytes. In vitro maturation of MI oocytes for a short period of time may increase the number of available embryos; however, overnight in vitro culture of MI oocytes did not improve results.

Rhesus macaque embryos derived from MI oocytes maturing after retrieval display high rates of chromosomal anomalies

BACKGROUND

Rhesus macaque and human preimplantation embryos display similar rates of chromosomal abnormalities. The aim of this study was to determine whether embryos developing from MI oocytes that mature post-retrieval display more chromosomal anomalies than those embryos that are generated from oocytes that are at MII at the time of retrieval.

METHODS

Rhesus macaque oocytes were obtained after hormonal ovarian stimulation. Immediately after retrieval, the oocytes were classified according to their maturational status. Following in vitro fertilization, Day 3 embryos with good morphology and development derived from oocytes maturing post-retrieval and those from oocytes that were mature at the time of retrieval were cytogenetically assessed using a five-color fluorescent in situ fluorescent hybridization assay developed for rhesus macaque chromosomes homologous to human chromosomes 13, 16, 18, X and Y.

RESULTS

Blastomeres from 53 embryos were analyzed. Of the 27 embryos that developed from oocytes that were mature at collection, 18 embryos were chromosomally normal (66.7%), while from the 26 embryos that developed from oocytes that matured post-retrieval, only 9 embryos were chromosomally normal (34.6%).

CONCLUSIONS

These results indicate that embryos developing from oocytes maturing post-retrieval display high rates of chromosomal abnormalities and have therefore a reduced developmental competence. As a result, the clinical relevance of using immature oocytes that are retrieved after stimulated cycles in human IVF warrants further investigation.

Successful delivery after the transfer of embryos obtained from a cohort of incompletely in vivo matured oocytes at retrieval time

OBJECTIVE

To report a case of successful delivery of a healthy baby after intracytoplasmic sperm injection (ICSI) in a patient with no mature oocytes at the time of oocyte retrieval.

DESIGN

Case report.

SETTING

Department of Reproductive Medicine.

PATIENT

After a controlled ovarian hyperstimulation cycle, a total of seven immature oocytes were collected.

INTERVENTION(S)

Medical management.

MAIN OUTCOME MEASURE(S)

The timing of polar body extrusion was checked every 2 hours, and ICSI was performed as soon as the first polar body was extruded.

RESULT(S)

Following incubation in culture medium, five oocytes reached the metaphase II stage within 8-8.5 hours. Three oocytes were fertilized after ICSI, and two of three cleaved embryos were transferred on day 3. The embryo transfer was followed by a single pregnancy and the delivery of a healthy baby.

CONCLUSION

This case report demonstrates that embryos obtained from in vitro matured oocytes retain the developmental competence for full-term. It illustrates the importance of regularly monitoring the polar body extrusion when all collected oocytes are immature.

Fertilization, embryo development, and clinical outcome of immature oocytes from stimulated intracytoplasmic sperm injection cycles

OBJECTIVE

To evaluate the fertilization and developmental potential of immature oocytes obtained from controlled ovarian hyperstimulated cycles of patients undergoing intracytoplasmic sperm injection (ICSI).

DESIGN

Retrospective study.

SETTING

Academic assisted reproductive technology program.

PATIENT(S)

Two hundred patients with at least one mature oocyte and one immature oocyte (study 1), and 44 patients with no mature oocytes (study 2) at time of oocyte denudation.

INTERVENTION(S)

Oocyte denudation was performed immediately after retrieval. Oocytes were cultured in vitro for 4-6 hours before ICSI and then categorized into four groups: group I, metaphase II (MII) oocytes at denudation; group II, in vitro matured MII oocytes; group III, metaphase I (MI) oocytes that did not progress to MII; and group 4, germinal-vesicle (GV) oocytes that converted to MI.

MAIN OUTCOME MEASURE(S)

Fertilization and embryo development were compared among groups in study 1. Pregnancy and implantation rates were evaluated in study 2.

RESULT(S)

Although the fertilization rate in group III was significantly lower than in groups I and II, no significant difference was found between groups I and II. Day 3 embryos in group I had the highest mean number of blastomeres, proportions of good embryos, and blastocyst formation rate when compared with groups II and III. Two clinical pregnancies were achieved from 26 transfer cycles in study 2, resulting in pregnancy and implantation rates of 7.7% and 4% per transfer cycle, respectively.

CONCLUSION(S)

Although our results show that immature oocytes from stimulated cycles can be normally fertilized and used to increase the number of embryos available for transfer, the increase in number of embryos derived from immature oocytes cannot be efficiently translated into pregnancies and live births. The clinical significance of using immature oocytes in stimulated cycles needs further investigation.

Effect of rescuing donated immature human oocytes derived after FSH/hCG stimulation following in vitro culture with or without Follicular Fluid Meiosis Activating Sterol (FF-MAS)--an embryo chromosomal and morphological analysis

PURPOSE

Studies in mice and humans have shown that Follicular Fluid - Meiosis Activating Sterol (FF-MAS) induces meiotic maturation of immature oocytes in vitro. A multicenter, prospectively randomised study evaluated chromosomal status of embryos from FSH/hCG primed human immature oocytes, cultured with or without FF-MAS.

METHODS

Denuded immature oocytes (n=365) were randomly allocated into inert control, FF-MAS 5 microM or 20 microM. Seventy +/-2 hours after ICSI on matured oocytes, all cleaved embryos were fixed for fluorescence in situ hybridisation analysis.

RESULTS

Only 15% of oocytes resulted in cleaved embryos. GV oocytes matured at significantly lower rates (14% and 7%) in the two FF-MAS groups compared to the inert control group (47%). High rates of chromosomal abnormalities were found in all groups.

CONCLUSION

Immature oocytes showed poor development with high rates of embryo chromosomal abnormalities. Exposure to FF-MAS in the concentrations, duration and/or formulation used in this study did not improve the results.

Pronuclear synchronization and nuclear morphology of mature and in vitro matured oocytes in the rat: an ultrastructural study

The objective of this study was to evaluate synchronous and asynchronous pronucleus (PN) formation and the related patterns of juxtapositional nucleolus (n) formation in immature (prophase I [PI] and metaphase I [MI]) and mature (metaphase II [MII]) oocytes after fertilization, both ultrastructurally and at the level of light microscope. A single dose of 15 IU gonadotrophin was injected subcutaneously to twenty four 26-wk-old, female Wistar rats to induce ovulation. Human chorionic gonadotrophin (4 IU) was administered 40 h later, and after 4-6 h the ovaries were dissected, and the oocytes were aspirated. A total of 214 rat oocytes were classified according to a maturation index as follows: group I, 80 PI oocytes; group II, 50 MI oocytes; and group III, 84 MII oocytes. Immature oocytes were in vitro matured for 18-36 h. Spermatozoa were acquired by microepididymal sperm aspiration and processed using swim-up technique. Intracytoplasmic sperm injection was performed on mature oocytes after 2 h of incubation and on in vitro matured (IVM) oocytes 4 h after maturation. Pronuclear synchronization [both pronucleases (PNs) centrally located, equal sized, with equal numbers and sizes of juxtapositional nucleoli (Nn)] was observed in fertilized oocytes. Asynchronous PN formation (diversity between male and female PNs, related to dimensions, localization, and the number of Nn) in groups I, II, and III was found in 75, 86, and 47% of preembryos, respectively. There was a significant difference of synchronous pronuclear formation between mature and IVM oocytes (P < 0.05). In IVM oocytes, asynchronous PN formation is high, and juxtapositional pronucleolar patterns are observed to be low by transmission electron microscope (TEM).

Human oocyte maturity in vivo determines the outcome of blastocyst development in vitro

PURPOSE

To date, the impact of oocyte maturity at aspiration on the blastocyst formation in vitro has not been fully evaluated. This study was undertaken to assess the influence of oocyte maturity in patients undergoing in vitro fertilization and blastocyst transfer program.

METHODS

A total of 1278 oocytes derived from 147-IVF cycles were retrospectivly analyzed. Oocyte maturity was graded on a scale from 1 to 5 based on the morphology of the ooplasm, cumulus mass, corona radiata, and membrana granulosa cells.

RESULTS

Mature oocytes yielded the highest fertilization rates. Although the cleavage rates were similar in both groups, the percentage of poor morphology, day-3 embryos from the nonmature-oocyte group was significantly higher than from the mature-oocyte group (54.7% vs. 15.5%, P < 0.001). Although good morphology, day-3 embryos were collected from nonmature oocytes, the incidence of these embryos developing to the blastocyst stage was significantly less than from mature oocytes (33.3% vs. 71.2%, P < 0.001). Although blastocyst stage embryos were collected from nonmature oocytes, the incidence of these embryos developing to the top-scoring blastocysts was significantly less than from mature oocytes (58.3% vs. 89.5%, P < 0.001).

CONCLUSIONS

These phenomena suggest that oocyte maturity produced in vivo determine the fertilization potential and subsequent blastocyst quality in vitro.

Impact of duration of cryopreservation of spermatozoa obtained through testicular sperm extraction on intracytoplasmic sperm injection

Cryopreservation of testicular spermatozoa is feasible for patients suffering obstructive or nonobstructive azoospermia. A stndardized intracytoplasmic sperm injection procedure using frozen-thawed testicular tissue gives rise to fertilization and cleavage rates, which appear not to be affected by the duration of the period of cryostorage.

The maturity of human cumulus-free oocytes is positively related to blastocyst development and viability

PURPOSE

We investigated whether the human oocyte maturity at the removal of cumulus/corona cells affects the embryo outcome in vitro.

METHODS

A total of 620 oocytes, which subsequently underwent blastocyst culture, were included in this analysis. Oocytes that were in prophase or Metaphase I of meiosis at the removal of cumulus/corona cells were in Group II. Oocytes that were in Metaphase II at the removal of cumulus/corona cells were in Group I.

RESULTS

Group I oocytes yielded the highest fertilization rates (96.3% vs. 77.1%, P < 0.001). The incidence of Group II oocytes developing to the blastocyst stage was significantly less than from Group I oocytes (38.1% vs. 86.1%, P < 0.001). The percentage of top-scoring blastocysts from Group I oocytes was higher than that of Group II oocytes (95.4% vs. 76.2%, P < 0.001).

CONCLUSIONS

Oocyte maturity at the removal of cumulus/corona cells needs to be considered in selecting good quality blastocysts for embryo transfer.

Ooplasmic influence on nuclear function during the metaphase II-interphase transition in mouse oocytes

Nuclear and pronuclear transfer procedures were used to assess the functional competence of the nucleus and cytoplasm of mouse germinal vesicle-stage oocytes denuded of granulosa cells and matured in vitro or in vivo before artificial activation using a sequential treatment of A23187 + cycloheximide. Following activation, in vitro-matured oocytes were "fertilized" by inserting a male pronucleus (PN), cultured to the 2-cell stage, and then transferred to the oviducts of foster mothers. No live births were noted, whereas a 17% live birth rate was observed when in vivo-matured oocytes were used. The developmental competency of other zygotes was similarly assessed following the exchange of haploid PN of matured and activated eggs with the female PN of fertilized zygotes. When PN of oocytes subjected to maturation and activation in vitro were transferred, only 1 of 79 reconstructed zygotes developed to term. In contrast, the live birth rate was 21% (11 of 53) for zygotes reconstructed with PN from in vivo-matured oocytes. Moreover, a live birth rate of 23% (8 of 35) was observed for reconstructed zygotes with female PN from "hybrid" oocytes created by transferring the metaphase II nuclei of in vitro-matured oocytes into enucleated, in vivo-matured oocytes before activation. Such results suggest that the nucleus of an in vitro-matured oocyte can support embryonic development, but only when it is activated in the proper ooplasmic milieu. The cellular factors creating this ooplasmic milieu appear to develop normally in vivo during follicle maturation to metaphase II, but they fail to do so when the oocytes are denuded of granulosa cells and cultured in vitro before the final stages of maturation. In parallel studies, male and female PN of in vivo-fertilized zygotes were inserted into oocytes that were activated and enucleated following either in vitro or in vivo maturation. Live birth rates were comparable at 19% (5 of 27) and 18% (9 of 49), respectively, suggesting that, regardless of the environment of the final stages of oocyte maturation, the resultant ooplasm is competent to support all aspects of embryonic development once activation and PN formation has been completed. Such findings only point further toward the importance of the condition of the ooplasmic milieu at the time of chemical activation. Whether a similar situation exists when eggs are activated following sperm penetration remains to be determined.

Determination of the efficiency of controlled ovarian hyperstimulation in the gonadotropin-releasing hormone agonist-suppression cycle using the initial follicle count during gonadotropin stimulation

PURPOSE

Our purpose was to evaluate the relationship between the initial follicle count during gonadotropin stimulation after gonadotropin-releasing hormone (GnRH) agonist suppression and the efficiency of controlled ovarian hyperstimulation (COH) in patients receiving treatment with assisted reproductive technologies (ARTs).

METHODS

A total of 338 COH procedures in 291 couples was performed with cycles that reached the stage of oocyte retrieval. The ovarian antral follicle number was measured using transvaginal ultrasonography at the folliculometry during gonadotropin stimulation by GnRH agonist suppression in patients undergoing ARTs. Controlled ovarian hyperstimulation was accomplished using GnRH agonist down-regulation combined with FSH and menotropin stimulation. The characteristics of oocytes after retrieval and embryos after in vitro culture and the pregnancy rates were assessed.

RESULTS

The procedures performed included 195 ET cycles, 129 TET cycles, and 14 incomplete cycles. The treatment cycles were divided into four categories according to the antral follicle number (i.e., < or = 5, 6-10, 11-15, and > or = 16) at the first folliculometry to evaluate the influence of various factors. The antral follicle count correlated significantly with the patient age, dosage of gonadotropins, serum estradiol concentration, number of antral follicles (> or = 13 mm) while receiving hCG injections, number of oocytes retrieved, and, later, number of embryos transferred. There was a trend toward an increasing number of pregnancies per cycle as the number of antral follicles increased (14.7, 26.5, 44, and 45%, respectively).

CONCLUSIONS

We were able to predict the efficiency of COH and outcome of ARTs based on the follicle count during the first folliculometry during gonadotropin stimulation after GnRH agonist suppression. The results of the folliculometry significantly predicted the ovarian response to COH and the outcome of ARTs in the current treatment cycle.

Two different timings of intrauterine insemination for non-male infertility

PURPOSE

Our purpose was to assess the simplicity and convenience of treatment scheduled not on weekends, by comparing two different timings of intrauterine insemination (IUI) protocol.

METHODS

A prospective observational study of two different protocols of intrauterine insemination was designed. Two hundred and ten infertile couples with normal spermiograms were included in this study. Fifty-eight couples were treated with IUI 26 to 28 h after human chorionic gonadotropin (hCG) injection plus timed intercourse within a 12- to 18-hr period and 147 couples had IUI 36 to 38 hr after hCG injection and timed intercourse within a 12- to 18-hour period. Pregnancy rates were compared with two different protocols of IUI.

RESULTS

The mean age, duration, and causes of infertility and the cycle characteristics following follicular stimulation were similar between the two groups. The cycle characteristics of follicular stimulation in the two treatment groups were not different. There also were no significant differences between the groups in the type of sperm concentration, sperm motility, and the percentage of sperm with normal morphology per insemination. The number of follicles greater than 17 mm per patient was not significantly different between the two groups. The pregnancy rate per cycle also was similar between the two groups in men with lower motile sperm numbers (< 40 x 10(6)) (23.6% vs. 23.4%) and in men with higher sperm numbers (> or = 40 x 10(6)) (25% vs. 24.4%).

CONCLUSIONS

The different timing but similar efficacy of these two IUI protocols provides a practical choice to clinicians. The availability of both protocols may avoid unnecessary scheduling of clinical and laboratory work on weekends and holidays in women participating in controlled ovarian hyperstimulation and IUI programs for treatment of non-male infertility.