Maturational asynchrony between oocyte cumulus-coronal morphology and nuclear maturity in gonadotropin-releasing hormone agonist stimulations

Assisted gamete treatment to pinpoint acquired meiotic maturity and overcome oocyte activation deficiency contributed by both gametes

Objective

To treat couples with total fertilization failure (TFF) based on a combined oocyte- and sperm-related oocyte activation deficiency by optimizing oocyte response to chemical activation with calcium ionophore.

Design

Case report.

Setting

Tertiary Hospital.

Patients

Two couples with a history of TFF after intracytoplasmic sperm injection intracytoplasmic sperm injection (ICSI).

Interventions

To overcome oocyte-related oocyte activation deficiency (OAD), extended in vivo/in vitro oocyte maturation was performed to enhance ooplasmic maturity; to address sperm-related OAD, assisted gamete treatment (AGT) was performed to trigger oocyte activation.

Main outcome measures

Treatment cycle outcomes for the 2 couples undergoing ICSI with extended oocyte maturation (EOM) and AGT.

Results

We identified 2 couples with TFF after ICSI because of a combined factor of OAD confirmed by phospholipase C zeta expression and genomic assessment. Initial AGT treatment alone failed to enhance fertilization, suggesting superimposed oocyte dysmaturity prohibiting oocytes from responding to chemical stimuli. To address this complex form of OAD, in couple 1, 27 oocytes out of 34 retrieved presented normal metaphase II spindles after EOM; ICSI with AGT yielded a fertilization rate of 63.0% (17/27). All 17 zygotes were cryopreserved initially. Two embryos were thawed and transferred, yielding a monochorionic diamniotic twin pregnancy. Couple 2 underwent 3 ICSI cycles with EOM and AGT; 91.4% (32/35) of oocytes displayed normal metaphase II spindle and achieved an overall fertilization rate of 43.8% (14/32). A total of 12 blastocysts were cryopreserved. A single 46XY blastocyst was thawed and transferred, resulting in a singleton pregnancy.

Conclusions

Our study has demonstrated the usefulness of EOM by targeting spindle presence to enhance chemical responses to AGT.

Oocyte retrieval and quality evaluation

After more than 30 years of harvesting oocytes for in vitro fertilization, collection techniques are well established. Presented here are dependable methods for maintaining environmental stability during such procedures and general descriptions of the materials collected.

Assisting in vitro fertilization by manipulating cumulus-oocyte-complexes either mechanically or enzymatically does not prevent IVF failure

OBJECTIVE

This prospective study was set up in order to analyze whether additional treatment (cutting off supernumerous cumulus cells; adding hyaluronidase) of the cumulus-oocyte-complex (COC) would help to improve treatment outcome.

MATERIAL AND METHODS

COCs from 50 patients were prospectively subdivided into a control group A (no manipulation of COC) and two study groups. In group B, surplus cumulus cells were cut off using syringes, and in the second study group COCs were incubated with a 1:11 dilution of hyaluronidase (final concentration 7 IU/l). Main outcome measures were fertilization rate, embryo development, as well as rates of implantation, pregnancy, and live birth.

RESULTS

Fertilization was higher in group C as compared to the untreated control group A (p<0.05). However, complete fertilization failure could not be avoided by any of the modified IVF approaches. Compaction on day 4 and blastocyst quality on day 5 were significantly improved in group C as compared to group B (but not to group A). Rates of implantation, pregnancy, and live birth were not affected by any of the methods.

CONCLUSION

ICSI seems to be the only choice for avoiding the vast majority of fertilization failures after IVF.

Follicular dominance on the fifth day of controlled ovarian stimulation reduces implantation in long down-regulated ICSI cycles

OBJECTIVE

To determine if follicular dominance on the fifth day of controlled ovarian stimulation (COS) predicts implantation rates in down-regulated intracytoplasmic sperm injection (ICSI) cycles.

STUDY DESIGN

One hundred and sixty-two consecutive women undergoing ICSI treatment with long down-regulation and recombinant follicle-stimulating hormone injections were included in a prospective cohort analysis. The clinical pregnancy and implantation rates per transfer were compared between two groups, one with and the other without follicular dominance detected by ultrasound on the fifth day of COS.

RESULTS

There was no significant difference between the groups regarding the number of good quality embryos transferred, but clinical pregnancy and implantation rate per transfer were higher in group with follicular synchrony.

CONCLUSIONS

Follicular dominance on COS day 5 results in reduced implantation rates after ICSI.

Blood clots in the cumulus-oocyte complex predict poor oocyte quality and post-fertilization development

Assessment of oocyte maturity and quality (morphological appearance) at the time of retrieval is difficult as the egg is obscured by a large cumulus mass that hinders adequate scoring. Since no data are available on the possible relationship between the cumulus-oocyte complex (COC) and oocyte morphology, this prospective intracytoplasmic sperm injection study was set up in 87 consecutive patients. COC were grouped according to expansion of both corona radiata and cumulus matrix. Special emphasis was placed on recording morphological anomalies of COC (inclusion of blood clots and amorphous clumps). For all mature ovae, quality was assessed and preimplantation development followed up to blastocyst stage if fertilized. The risk of not harvesting an oocyte was higher in COC with blood clots compared with normal cumulus matrices (P = 0.004). COC expansion did not allow for prediction of either nuclear status or quality of the egg. The presence of blood clots within the cumulus matrix was associated with reduced oocyte quality (dense central granulation), fertilization rate and blastocyst formation, compared with unaffected COC (P < 0.05). It may be postulated that COC showing blood inclusions derive from poor quality follicles, which has a detrimental effect on oocyte quality and further cleavage to blastocyst stage. Consequently, mechanical removal of blood clots cannot rescue the corresponding embryo.

Glutathione S-transferase theta 1 expressed in granulosa cells as a biomarker for oocyte quality in age-related infertility

OBJECTIVE

The goal of this study was to identify a reliable biomarker for age-related infertility.

DESIGN

Laboratory study.

SETTING

ART laboratory.

PATIENT(S)

Patients undergoing intracytoplasmic sperm injection or IVF cycles.

INTERVENTION(S)

Expression of Glutathione S-transferase (GST) mRNA and protein in mural and cumulus granulosa cells obtained from infertile patients were examined by reverse transcriptase-polymerase chain reaction and immunofluorescence.

MAIN OUTCOME MEASURE(S)

Correlation between the expression of GST theta 1 (GSTT1) in granulosa cells and oocyte quality was a main outcome measure.

RESULT(S)

Expression of GSTT1 in granulosa cells from male factor patients was positively correlated with age and negatively with cumulus-oocyte complex maturity. When samples with high and low GSTT1 in granulosa cells were extracted from the other infertility factors, cumulus-oocyte complex maturity in the high GSTT1 group was significantly lower than that in the low GSTT1 group (high: 27.2% vs. low: 51.3%). The developmental capacity of oocytes in the high GSTT1 group was likely to be lower (high: 26.4% vs. low: 43.9%). Up-regulation of GSTT1 during aging may be promoted by FSH and H(2)O(2), determined by an in vitro model.

CONCLUSION(S)

GSTT1 is a good indicator for age-related infertility.

Comparison of Ca2+ and CaMKII responses in IVF and ICSI in the mouse

Novel methods of egg activation in human assisted reproductive technologies and animal somatic cell nuclear transfer are likely to alter the signalling process that occurs during normal fertilization. Intracytoplasmic sperm injection (ICSI) bypasses the normal processes of the acrosome reaction, sperm-egg fusion, and processing of the sperm plasma membrane, as well as alters some parameters of intracellular calcium ([Ca(2+)](i)) dynamics (reported previously by Kurokawa and Fissore (2003)). Herein, we extend these studies to determine if ICSI alters the activity of the Ca(2+)-dependent protein, Ca(2+)/calmodulin-dependent kinase II (CaMKII), which is responsible for the completion of meiosis in vertebrate eggs. After ICSI or in vitro fertilization (IVF), individual mouse eggs were monitored for their relative changes in both [Ca(2+)](i) and CaMKII activity during the first [Ca(2+)](i) rise and a subsequent rise associated with second polar body extrusion. The duration of the first [Ca(2+)](i) rise was greater in ICSI than in IVF, but the amplitude of the rise was transiently higher for IVF than ICSI. However, a similar mean CaMKII activity was observed in both procedures. During polar body extrusion, the amplitude and duration of the Ca(2+) rises were increased by a small amount in ICSI compared with IVF, whereas the CaMKII activities were similar. Thus, compared with IVF, ICSI is not associated with decreased or delayed CaMKII activity in response to these Ca(2+) signals in the mouse.

Secretory mechanisms and Ca2+ signaling in gametes: similarities to regulated neuroendocrine secretion in somatic cells and involvement in emerging pathologies

Recent studies demonstrate that regulated secretion in probably all mammalian cells, from gonadotropes to gametes, utilizes similar signaling systems, intracellular Ca(2+) regulation, Ca(2+)-dependent proteins, cytoskeletal participation, and SNARE-mediated fusion. Thus, highly specialized cells, like sperm and eggs, should no longer be considered to have evolved a cell-type specific secretory mechanism. In gametes, Ca(2+)-dependent proteins and enzymes transduce elevations of intracellular Ca(2+) into secretory events, i.e., exocytosis of the acrosome in sperm and cortical granules in the egg. Just as secretory deficiencies have clinical consequences in endocrine and exocrine cells, failure of secretion of cortical granules or the acrosome can result in failure of normal fertilization or fertilization followed by abnormal development. With the advent of human in vitro fertilization, such gamete pathologies have been recently identified and have led to new clinical procedures to achieve normal fertilization and pregnancies. A better understanding of the common Ca(2+)-dependent secretory pathways in both gametes and somatic cells should be beneficial to investigating mis-regulation in either cell type.

Effect of oocyte morphology on embryo development and implantation

Assessment of oocyte morphology is a difficult task, since underlying mechanisms that change the appearance of the oocyte are multifactorial and complex. Significant morphological variations are known to exist among oocytes that may affect the developmental competence and implantation potential of the derived embryo. Morphological variations of the oocyte may result from intrinsic factors such as age and genetic defects or extrinsic factors such as stimulation protocols, culture conditions, and nutrition. The effect of these morphological variations of the oocyte on embryo development and implantation, however, is not conclusively defined because of methodological flaws inherent to most of the studies in the literature. This review will mainly discuss morphological markers of oocyte quality/viability in relation to the oocyte morphology and attempt to clarify whether morphological evaluation of the oocyte can be utilized for predicting the implantation potential of the derived embryo.

Cumulus Cells Accelerate Aging of Mouse Oocytes1

The role of cumulus cells (CCs) that surround oocytes in maturation, ovulation, and fertilization has been extensively studied, yet little is known about their role in oocyte aging. Although early studies have shown that when ovulated oocytes are aged in vitro displayed similar morphological alterations as those aged in vivo, a recent study found that vitro culture of mouse oocytes retarded oocyte aging. The objective of this study was to test the hypothesis that CCs would accelerate oocyte aging. During in vitro aging with CCs of both in vivo-matured and in vitro-matured mouse oocytes, activation rates increased, whereas the maturation-promoting factor (MPF) activity decreased significantly as during in vivo aging of the ovulated oocytes. During aging after denudation of CCs, however, activation rates of both in vivo-matured and in vitro-matured oocytes remained low and the MPF activity decreased much more slowly compared to that of oocytes aged with CCs. Although many oocytes aged in vivo and in vitro with CCs showed a partial cortical granule (CG) release, very few cumulus-free oocytes released their CGs during in vitro aging. When denuded oocytes were cultured with cumulus-oocyte-complexes at a 1:2 ratio or on a CC monolayer, activation rates increased, while MPF activity decreased significantly. The results strongly suggested that CCs accelerated the aging progression of both in vivo-matured and in vitro-matured mouse oocytes.

Selective early elimination of luteal support in assisted reproduction cycles using a gonadotropin-releasing hormone agonist during ovarian stimulation

OBJECTIVE

To determine if women undergoing GnRH agonist-hMG stimulated IVF cycles can undergo successful discontinuation of luteal phase support.

DESIGN

A protocol for selective discontinuation of luteal phase support was evaluated prospectively in women undergoing assisted reproduction cycles.

SETTING

A tertiary care institutional-based assisted reproduction program.

PATIENT(S)

One hundred eighty-eight women who conceived after an IVF or zygote intrafallopian transfer cycle including a GnRH agonist between January 1994 and June 1997.

INTERVENTION(S)

Women with serum progesterone levels of > or = 60 ng/mL at 4 weeks' gestation were selected for discontinuation of their luteal phase support.

MAIN OUTCOME MEASURE(S)

Delivery rate.

RESULT(S)

Sixty-three women (62.4%) met the criteria for discontinuation of luteal phase support. There were no differences in the mean age, peak E2 levels, number of follicles, number of embryos transferred, or delivery rates (85.7% versus 78.9%) between the women who did and those who did not have discontinuation of their progesterone supplementation.

CONCLUSION(S)

These data reveal that luteal phase support can be discontinued successfully for selective women undergoing IVF who are receiving a GnRH agonist.

Biochemical and cellular insights into the temporal window of normal fertilization

Normal development depends on both the timing of fertilization and gamete quality, especially in assisted reproductive procedures. Recent studies of the proteins involved in the polyspermy block and cell cycle progression provide a cellular and biochemical basis for the short fertilizable lifespan of the mammalian egg in several species. Specifically, the status of cortical granules, zona proteins, cell cycle kinases, and intracellular calcium stores form a powerful panel of assays to monitor egg activation competence in eggs undergoing maturation and spontaneous activation events in mature eggs. An understanding of how these indicators are influenced by in vitro conditions and exogenous follicular stimulation should provide useful information for optimizing assisted reproductive procedures.

Treatment variables in relation to oocyte maturation: lessons from a clinical micromanipulation-assisted in vitro fertilization program

OBJECTIVE

In an effort to understand the mechanism underlying the improved pregnancy rate observed in IVF cycles when gonadotropin-releasing hormone analogues (GnRH-a) are applied, we investigated a possible relationship between treatment variables and oocyte nuclear maturity.

DESIGN

Nuclear maturity was retrospectively assessed in cumulus-free, denuded oocytes, obtained from women undergoing micromanipulation-assisted IVF treatment following controlled ovarian hyperstimulation with GnRH-a and menotropins.

SETTING

The setting was the infertility and IVF unit of a tertiary academic medical center.

PARTICIPANTS

Two hundred twenty-one patients underwent 435 treatment cycles.

MAIN OUTCOME MEASURE

This was the proportion of germinal vesicle-intact immature (GVII) oocytes.

RESULTS

One hundred fifty-four of the 3520 oocytes studied (4.4%) were in the GVII stage. These oocytes were found in 66 of the treatment cycles (15.2%) and in 54 of the patients (24.4%). Cycles in which GVII oocytes were detected did not differ from those in which all the aspirated oocytes were mature in the following respects: patient age, type and duration of infertility, controlled ovarian hyperstimulation protocol and time of ovum pickup. However, the GVII group was characterized by a significantly higher peak estradiol level, as well as a higher number of mature follicles visualized sonographically (diameter, > 14 mm) and oocytes retrieved.

CONCLUSIONS

Comparing the present findings with previously published data, it appears that the inclusion of GnRH-a in the stimulation regimen is associated with a lower proportion of immature oocytes. A higher occurrence of oocyte-nuclear immaturity is apparently associated with a significantly better ovarian response to stimulation. The high incidence of immature oocytes observed in patients with normospermic partners and low fertilization rates in previous cycles may suggest that the fertilization failure in some of these cases is due to oocyte, rather than sperm, dysfunction.

Delayed embryo implantation following in vitro fertilization and embryo transfer (IVFET)

PURPOSE

Our goal was to compare serum human chorionic gonadotropin (hCG) levels in singleton pregnancies achieved following IVFET with those achieved following spontaneous conception.

RESULTS

The mean serum hCG level of patients who became pregnant following IVFET lagged 1.5 days behind that of patients who became pregnant spontaneously.

CONCLUSIONS

The use of gonadotropin releasing hormone analogue as part of the stimulation protocol leading to egg retrieval and IVFET results in a delay in embryo implantation.

The correlation between follicular measurements, oocyte morphology, and fertilization rates in an in vitro fertilization program

OBJECTIVE

To explore the relationship between follicle size and the morphology of the oocyte-cumulus-corona complex with fertilization rates in stimulated cycles of IVF.

DESIGN

Retrospective comparison of measurements and observations of 2,429 oocytes from 215 patients undergoing 324 stimulated IVF cycles.

SETTING

A large hospital-based IVF program.

MAIN OUTCOME MEASURES

Individual follicles were measured by ultrasound before transvaginal aspiration and the size was recorded. The oocyte-cumulus-corona complex from each follicle was examined and classified. The oocytes were checked for evidence of fertilization 17 to 22 hours after insemination.

RESULTS

The fertilization rate of all oocytes regardless of morphological type revealed a positive linear correlation with increasing follicle diameter. The fertilization rates of type I oocytes was marginally higher than type II oocytes, controlling for follicle diameter; however, this difference did not achieve statistical significance. Oocytes from follicles with a mean diameter > or = 16 mm had significantly higher fertilization rates than did oocytes from follicles with a mean diameter < or = 14 mm.

CONCLUSIONS

Follicle size is a better predictor of fertilization than is morphological characterization of the oocyte-cumulus-corona complex in IVF.

Tubal versus uterine transfer of cryopreserved embryos: a prospective randomized trial

OBJECTIVE

To compare pregnancy rates after fallopian tubal and uterine transfer of cryopreserved embryos.

DESIGN

Prospective randomized trial with assignment to treatment groups by a random number table.

SETTING

University of Iowa Hospitals and Clinics, a tertiary care academic institution.

PATIENTS

Forty patients with patent fallopian tubes and at least three cryopreserved embryos.

INTERVENTIONS

Cryopreserved embryos were thawed and transferred to the fallopian tube by laparoscopy or to the uterus by a transcervical catheter.

MAIN OUTCOME MEASURES

Clinical and ongoing pregnancy rates.

RESULTS

Tubal transfer of cryopreserved embryos resulted in statistically higher clinical (68% versus 24%) and ongoing pregnancy rates (58% versus 19%) when compared with uterine transfer.

CONCLUSIONS

Tubal transfer of cryopreserved embryos is highly effective and offers an improved pregnancy rate when compared with uterine transfer of embryos. This method of transfer should be considered in patients with patent fallopian tubes and at least three cryopreserved embryos.

The abnormally large follicle during controlled ovarian hyperstimulation: management and outcome of the cycle

OBJECTIVE

To investigate if the presence of an abnormally large follicle during controlled ovarian hyperstimulation (COH) under pituitary suppression has any effect on the outcome of the cycle.

DESIGN

Prospective, observational.

SETTING

The reproductive endocrinology unit of a university hospital.

PATIENTS

One hundred fifty patients undergoing COH for assisted reproductive techniques during a 6-month period (August 1990 to January 1991).

INTERVENTIONS

Transvaginal follicular aspiration and IVF-uterine ET.

RESULTS

A total of 19 cycles had abnormally large follicles identified on day 8 of the stimulation cycle after normal baseline ultrasound. Gonadotropins were continued and hCG injection was indicated when two or more follicles of the main cohort achieved a diameter of 20 to 22 mm. Twenty preovulatory oocytes were retrieved from 22 large follicles. Two were transferred for GIFT and 18 were inseminated in vitro, resulting in a 72.0% fertilization rate. The mean number of oocytes retrieved per patient was 10.9, 71.4% of which were mature with a fertilization rate of 67.7%. All these figures were comparable with the results obtained in the 131 patients of the control group undergoing IVF. No evidence of premature luteinization was observed in the study group, based on plasma P levels (x 0.83 ng/mL [conversion factor to SI unit, 3.180], range 0.31 to 1.40 ng/mL). The clinical pregnancy rate for the group with abnormally large follicles did not differ from the control group (27.8% versus 28.2%, respectively).

CONCLUSIONS

The presence of an abnormally large follicle during COH under pituitary suppression does not affect the outcome of the cycle. Moreover, under these conditions, continuous gonadotropin stimulation of a follicle to diameters considerably larger than the standard ones does not have a detrimental effect on the oocyte contained in it, suggesting that oocyte aging is an independent process from follicular growth once LH surge is prevented.