Fertilization, Embryo Quality, and Cryosurvival in In Vitro Fertilization and Intracytoplasmic Sperm Injection Cycles

Purpose: Our purpose was to investigate the influence of semen quality on fertilization, embryo morphology, cleavage, and cryosurvival in conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI)programs. Methods: A retrospective analysis of 513 couples undergoing IVF and 255 couples undergoing ICSI was done. Results: Semen quality influenced fertilization in IVF and abnormal fertilization in IVF and ICSI, but no effects on the development, morphology, implantation capacity, or cryosurvival of embryos were found. Fertilization, embryo quality, and cryosurvival rates were similar after IVF and ICSI. The fertilization rate of mature oocytes in IVF was lower when cytoplasmic immaturity in the oocyte population was frequent. The speed of development of embryos was 2 hr faster after ICSI than after IVF. Two-cell–stage embryos survived best after cryopreservation with propanediol and sucrose on day 2. Conclusions: After fertilization, semen parameters had no effect on the quality or cryosurvival of embryos in either IVF or ICSI.     

Comparison of in-vitro outcomes from cryopreserved oocytes and sibling fresh oocytes

In Italy, the restrictive IVF law generalizes the indication for oocyte freezing for surplus oocytes in 78.5% of in-vitro assisted reproductive cycles. With a view to understanding better what the prospects for intracytoplasmic sperm injection (ICSI) on frozen-thawed oocytes might be, the consequences of freeze-thaw procedures on fertilization, cleavage rates and embryo quality obtained from frozen-thawed oocytes were studied and compared with the results obtained from sibling fresh oocytes. Eleven IVF and 29 ICSI on 76 and 169 fresh oocytes were performed and the corresponding 40 ICSI on 221 sibling frozen-thawed oocytes. There was no difference in terms of fertilization rate between fresh and sibling frozen-thawed oocytes. The cleavage rate (98.0 and 94.4% with fresh oocytes in IVF and ICSI; 77.3% with frozen-thawed oocytes in ICSI; P < 0.001) and embryo quality (grade I embryos over total embryos: 36.7 and 22.2% with fresh oocytes in IVF and ICSI; 12.1% with frozen-thawed oocytes in ICSI; respectively P < 0.001 and P < 0.05) were statistically lower after oocyte cryopreservation. The significant decrease in meiotic spindle retrieval rate before freezing (62.4%) and after thawing procedures (43.4%; P < 0.001) suggests that cryoconservation induces irreversible damage to microtubule repolymerization. The consequences of oocyte cryopreservation procedures on embryo development are reviewed.     

Experience with subzonal insemination (SUZI) and intracytoplasmic sperm injection (ICSI) on unfertilized aged human oocytes

Objective The aim of this study was to assess the fertilizability of unfertilized aged human oocytes from failed in vitro fertilization (IVF) cycles using SUZI and ICSI.Methods A total of 363 oocytes which showed no fertilization after conventional IVF was subjected to assisted fertilization using SUZI or ICSI. The microinjected oocytes which were derived from 72 patients undergoing their first IVF treatment had an intact polar body and no signs of degeneration. SUZI was carried out in 265 oocytes and ICSI in the remaining 98.Results Significantly more oocytes were damaged after ICSI (9 vs 0.3%, P<0.07). Normal fertilization rates were higher at 24 hr in both groups and occurred more frequently after ICSI, although the difference did not reach statistical significance. Abnormal fertilization occurred significantly more often after SUZI at 48 hr (P<0.005), but not at 24 hr. Cleavage rates were significantly higher after ICSI (94.4 vs 57.1%, P<0.025) at 24 hr, but this was not observed at 48 hr, although the ICSI group still showed better cleavage rates (33.3 vs 19.1%). There was no difference in embryo quality in either group.Conclusions Our results indicate that micromanipulation rather than reinsemination should be carried out on unfertilized human oocytes from failed IVF attempts. Both techniques can be used to achieve fertilization which occurs more often after ICSI. However, the trauma from the former technique on the microinjected oocytes may impair the potential of the generated embryos to achieve pregnancy compared to SUZI. Prospective randomized trials are necessary to address the problem.     

Intracytoplasmic sperm injection and conventional in vitro fertilization for sibling oocytes in cases of unexplained infertility and borderline semen

Purpose: In a prospective study, conventional IVF and intracytoplasmic sperm injection (ICSI) were performed on sibling oocytes of 22 patients with unexplained infertility (Group A) and 24 patients with borderline semen (Group B).Results: In Group A, there was no significant difference (P=0.070) in the fertilization rate per oocyte between ICSI (63%) and conventional IVF (50.7%), however, there was total failure of fertilization in conventional IVF in 5 of the 22 patients with IVF and none in ICSI. In group B, there was a significant difference (P<0.001) between the fertilization rate per oocyte in ICSI (59%) and conventional IVF (27.1%). There was total failure of fertilization in 11 patients after conventional IVF and none after ICSI.Conclusions: The study showed that 22.7% of unexplained infertility and 45.8% of patients with borderline semen would have lost their chance of embryo transfer completely because of total failure of fertilization if ICSI was not performed on some oocytes in this cycle.Presented in part at the IXth World Congress on In Vitro Fertilization and Alternate Assisted Reproduction, Vienna, Austria, April 3–7, 1995.     

Intracytoplasmic single sperm injection: preclinical training and first clinical results

Objective Our purpose was to reduce oocyte damage before clinical application of intracytoplasmic single sperm injection by training on aged unfertilized oocytes.Design Intracytoplasmic single sperm injection (ICSI) was accomplished by micromanipulation of sperm and oocytes.Patients Thirty-four patients consented to donate unfertilized aged oocytes to train for ICSI. Forty-four patients suffering from severe male infertility were treated with ICSI.Intervention Oocytes were inseminated by intracytoplasmic single sperm injection.Main outcome measures Oocyte damage and fertilization and pregnancy rates were the outcome measures.Results One hundred fifty-one aged unfertilized oocytes were gathered for training of which 121 were injected with a single sperm and 30 without a spermatozoon as a control group for activation. Oocyte damage, initially as high as 40%, was reduced to 15% after 60 oocytes. Normal fertilization (2PN) occurred in 18%, and polyploidy in 4.4%. The cleavage rate was 69%; none of these embryos were transferred. In the control group, seven oocytes were damaged, seven (30%) showed one pronucleus, and one showed two pronuclei. No cleavage was observed in the control group. In the clinical trial, 44 patients (61 cycles) were clinically treated with the same ICSI procedure, including 575 of 721 collected oocytes. Damage was 13%, activation was 11%, normal fertilization was 30%, and 5 (1%) polypoid zygotes were observed. The fertilization rate ranged from 5 to 100%, with a mean of 39.5±4% (SE). Nine patients had no fertilization (15%). Ninetysix percent of the zygotes cleaved and 47% were at the four-cell stage 45 hr after injection. One hundred twelve embryos were replaced in 48 transfers (2.3 embryos/ET). One live birth, one miscarriage, and eight ongoing pregnancies were obtained (22%/ET).Conclusion Preclinical practice on aged unfertilized oocytes seems useful before starting clinical ICSI, as the high initial oocyte damage can be reduced and subsequent clinical treatment successfully applied.     

Intracytoplasmic sperm injection as a treatment for unexplained total fertilization failure or low fertilization after conventional in vitro fertilization

OBJECTIVE: To determine whether IVF or intracytoplasmic sperm injection (ICSI) should be the choice of treatment in case of a previous IVF attempt with unexplained total fertilization failure or low fertilization (<25%). DESIGN: Prospective study. SETTING: Leiden University Medical Center. PATIENT(S): Thirty-eight couples undergoing IVF and ICSI on sibling oocytes after a first IVF attempt with total fertilization failure or with low fertilization (<25%). INTERVENTION(S): Performing IVF and ICSI on sibling oocytes. MAIN OUTCOME MEASURE(S): Fertilization and (ongoing) pregnancy rate. RESULT(S): A total of 271 oocytes were collected in 24 oocyte retrievals in the total fertilization failure group. Hundred nine oocytes were randomly allocated to IVF and 12 were fertilized (11%); 162 sibling oocytes were allocated to ICSI and 78 were fertilized (48%). In 8 of the 24 patients fertilization occurred after IVF. The pregnancy rate after transfer of 1 IVF and 1 ICSI embryo (n = 3) was 67% and after the transfer of 2 ICSI embryos (n = 21) this was 52%. In the low fertilization group 169 oocytes were collected in 14 oocyte retrievals. Seventy-two oocytes were randomly allocated to IVF and 16 were fertilized (22%). Ninety-seven sibling oocytes were allocated to ICSI and 58 were fertilized (60%). In 7 of 14 patients fertilization occurred after IVF. The pregnancy rate after the transfer of 1 IVF and 1 ICSI embryo (n = 5) was 80% and after the transfer of 2 ICSI embryos (n = 9) this was 33%. CONCLUSION(S): Performing ICSI on some oocytes of a cohort may avoid total fertilization failures both in patients with a history of total fertilization failure and in patients with a history of low fertilization, as the percentage of fertilization is higher after ICSI compared to IVF and the recurrence of total fertilization failure and low fertilization is high after IVF treatment.     

卵母细胞单精子显微注射治疗男性因素及不明原因不育

目的：研究应用卵母细胞单精子显微注射（ｉｎｔｒａｃｙｔｏｐｌａｓｍｉｃｓｐｅｒｍｉｎｊｅｃｔｉｏｎ，ＩＣＳＩ）技术，治疗因严重男性因素及不明原因引起不育患者的价值。方法：于１９９４年１２月，应用ＩＣＳＩ技术治疗３１例严重少、弱、畸精症及不明原因不育夫妇。按常规超排卵治疗，经阴道Ｂ超介导取卵，行成熟卵母细胞单精子显微注射受精。结果：２３７个成熟卵母细胞中，２１３个卵子存活，其中正常受精卵子１３２个，正常受精率为６２．０％。至１９９６年４月３０日，已有８例临床妊娠，临床妊娠率为２５．８％，其中１例在１９９６年１０月３日，于妊娠３９周＋３顺利分娩一婴儿。结论：ＩＣＳＩ技术用于治疗严重少弱畸精症及不明原因不育夫妇是适宜的。     

Meiotic spindle presence and oocyte morphology do not predict clinical ICSI outcomes: a study of 967 transferred embryos

With a view to correlating oocyte morphology and meiotic spindle presence to clinical intracytoplasmic sperm injection (ICSI) outcomes, 967 oocytes that led to 967 transferred embryos in 404 embryo transfers were studied. No relationship was found between oocyte morphology (ooplasm texture, perivitelline space largeness, perivitelline space granulation absence/presence and the first polar body shape) or meiotic spindle presence or absence and clinical pregnancy per transfer and implantation rates after ICSI. It was concluded that oocyte morphology and meiotic spindle presence or absence can only predict fertilization, cleavage rates and embryo quality, as previously described in the literature, but do not help in daily ICSI practice in the choice of the metaphase II oocyte that will lead to the embryo that starts clinical pregnancy.     

Phospholipase C-zeta deficiency as a cause for repetitive oocyte fertilization failure during ovarian stimulation for in vitro fertilization with ICSI: a case report

Purpose

The purpose of this study is to describe impaired oocyte fertilization from phospholipase C-zeta (PLC-ζ) deficiency in normal-appearing sperm that was successfully treated using calcium (Ca²⁺) ionophore with intracytoplasmic sperm injection (ICSI) of oocytes matured in vitro.

Methods

An infertile couple undergoing in vitro fertilization (IVF) experienced failed oocyte fertilization following ICSI with normal-appearing sperm. A semen sample collected from the patient was used to assess the expression of sperm PLC- ζ protein by Western blot analysis and immunofluorescence and PLC-ζ bioactivity by an in vitro model of Ca²⁺ release. A second IVF cycle was performed using Ca²⁺ ionophore with ICSI to enhance Ca²⁺-induced oocyte activation of oocytes matured in vitro.

Results

Sperm PLC-ζ protein deficiency was demonstrated by Western blot analysis and immunofluorescence and confirmed by reduced PLC-ζ bioactivity using an in vitro model of Ca²⁺ release. Nevertheless, with this sperm and supplementation of Ca²⁺ ionophore following ICSI, fertilization of four of six oocytes matured in vitro was obtained. In addition, four embryos underwent cleavage and two of them reached the blastocyst stage. Transfer of these blastocysts into the uterus led to a single pregnancy and live birth.

Conclusions

Deficiency of PLC-ζ in normal-appearing human sperm is associated with impaired Ca²⁺-dependent oocyte activation during ICSI. Under this condition, use of Ca²⁺ ionophore following ICSI of oocytes matured in vitro improves embryo developmental competence, possibly through the activation of Ca²⁺-dependent mechanisms governing fertilization and preimplantation embryogenesis.     

Fertilization and Development of a Blastocyst-Stage Embryo After Selective Intracytoplasmic Sperm Injection of a Mature Oocyte from a Binovular Zona Pellucida: A Case Report

Purpose: Our purpose is to describe the development of a blastocyst-stage embryo after the selective fertilization of a mature oocyte from a binovular zona pellucida by intracytoplasmic sperm injection (ICSI). Method: A 34-year-old woman underwent intracytoplasmic sperm injection due to severe male-factor infertility. After oocyte retrieval, a binovular zona pellucida including one mature metaphase II oocyte and one immature oocyte at the germinal vesicle stage as well as nine metaphase II oocytes was injected with spermatozoa using a one-to-one approach. Results: The injected mature oocyte of the binovular zona pellucida showed fertilization as evidenced by the presence of two pronuclei and cleaved to a four-cell embryo on the second day, while the uninjected oocyte showed signs of degeneration. On the third day, this embryo further cleaved to six blastomeres with slight fragmentation and it reached the blastocyst stage on the sixth day. Conclusions: Selective fertilization of one oocyte from a binovular zona pellucida by ICSI may lead to the development of a morphologically normal blastocyst-stage embryo which can be used for embryo transfer in the presence of a limited number of embryos.     

Impact of oocyte pre-incubation time on fertilization, embryo quality and pregnancy rate after intracytoplasmic sperm injection

Although, it is well known that pre-incubation of oocytes prior to conventional IVF improves fertilization and pregnancy rates, there are conflicting results regarding the effect of pre-incubation time in ICSI. This study evaluated the role of pre-incubation of oocytes on outcome in intracytoplasmic sperm injection (ICSI) cycles. A total of 1260 patients undergoing their first ICSI cycles were evaluated retrospectively. In patients undergoing ICSI during the year 2000 (Group I, n = 670), oocytes were injected immediately after retrieval, whereas in patients undergoing ICSI during 2001 (Group II, n = 590), oocytes were incubated for 2-4 h prior to injection. The mean age of patients was 33.9 +/- 5.04 years and 34.1 +/- 5.06 years in groups I and II, respectively. The number of oocytes with a first polar body (MII) and fertilization and cleavage rates were higher, and embryo quality was significantly better in group II. In contrast, the total numbers of oocytes without a first polar body (MI), those where germinal vesicle breakdown had not occurred (GV), and empty zona oocytes were higher in group I. No difference was found in the number of embryos transferred or implantation or clinical pregnancy rates. This study demonstrated that pre-incubation of oocytes prior to ICSI is associated with improved maturation of oocytes, fertilization and embryo quality.     

Correlation between oocyte preincubation time and pregnancy rate after intracytoplasmic sperm injection

Background and aim. Both nuclear and cytoplasmic maturation of oocytes have to be completed in a coordinated manner to ensure optimal conditions for fertilization. This is well known for in vitro fertilization, but is debated for intracytoplasmic sperm injection (ICSI). It has been reported that preincubation of oocytes prior to ICSI is associated with improved maturation of oocytes, fertilization and embryo quality. Therefore, in the present study, we evaluated the fertilization rate, embryo quality and pregnancy rate in relation to incubation times of metaphase-II oocytes before ICSI.

Method. We analyzed 135 selected ICSI cycles. Subjects were assigned to six groups according to oocyte incubation time before ICSI: 2–4 h, 5 h, 6 h, 7 h, 8 h and 9–12 h.

Results. We observed that the fertilization rate increased slightly at short (2 to 6 h) and then decreased at longer preincubation times (7 to 12 h). Concomitantly, cleavage rate increased up to 6 h of preincubation and decreased significantly in the groups in which ICSI was carried out after 7 to 12 h of incubation. With regard to clinical pregnancy rate, we observed a significant increase from 2 to 5 h of preincubation, when this parameter reached its maximum value (35%), tapering to 33% after 6 h and then dropping sharply to 12 h.

Conclusions. These data confirm that the most appropriate incubation time for mature oocytes before ICSI is 5–6 h. This time improves embryo quality and pregnancy rate in ICSI cycles.     

Successful pregnancy following transfer of embryos from oocytes with abnormal zona pellucida and cytoplasm morphology

The failed or impaired fertilization in an IVF cycle may be a result of undetected abnormalities in sperm function, poor oocyte quality, or impaired spermatozoon-oocyte interaction. Whether oocyte dysmorphisms have an impact on intracytoplasmic sperm injection (ICSI) outcome, fertilization, and implantation is controversial. A 33-year-old nulligravida female with a 2-year history of primary infertility was referred to the Toronto Centre for Advanced Reproductive Technology for infertility management. The patient underwent several cycles of ovulation induction followed by timed intercourse or intrauterine insemination without a resulting pregnancy. Following the failed insemination cycles, she proceeded to IVF. Six morphologically abnormal oocytes (including three that were cucumber-shaped) were retrieved and all injected with a single spermatozoon. Four oocytes showed normal fertilization and developed to day-3 embryos with abnormal morphology and were transferred. Two weeks after the embryo transfer, the patient had a positive beta-human chorionic gonadotrophin (beta-HCG). The pregnancy was uneventful, and a healthy baby boy was delivered at 41 weeks of age by Caesarean section. Since fertilization, embryo development, and successful pregnancy was achieved in this case, it is recommend that oocytes with extreme morphological abnormalities should not be discarded as ICSI may overcome the barriers to fertilization and cleavage.     

Percutaneous epididymal sperm aspiration and short time insemination in the treatment of men with obstructive azoospermia

Objective

To study the efficacy of percutaneous epididymal sperm aspiration (PESA) in combination with short time insemination to treat infertile men with obstructive azoospermia (OA).

Design

Paired randomized controlled trial in which each couple’s cohort of oocytes was divided into two equal groups.

Setting

Center for reproductive care.

Patients

Twenty men with OA.

Interventions

Motile spermatozoa were collected using PESA. Half of the oocytes were used for intracytoplasmic sperm injection (ICSI). The rest were inseminated briefly with PESA sperm in vitro fertilization (IVF). After 4–5 h, the remaining cumulus cells were removed mechanically for second polar body observation to decide whether to apply “rescue” ICSI (RE-ICSI).

Main outcome measures

Rates of oocyte maturation, fertilization, cleavage, and good quality embryos. Numbers of available embryos and good quality embryos were compared between PESA-IVF (using a short incubation protocol + rescue ICSI) group and PESA-ICSI group.

Results

In the short time insemination group, cumulus cells were dispersed by PESA spermatozoa. No second polar bodies were found, so RE-ICSI was done. PESA-IVF + RE-ICSI and PESA-ICSI outcomes were comparable in terms of fertilization rates, 2PN cleavage rate and good quality embryo rates with no statistically significant differences.

Conclusions

PESA sperm without centrifugation could disperse the cumulus cells but were infertile and therefore could substitute for synthetic hyaluronidase. The outcomes of PESA-IVF with rescue ICSI were equivalent to PESA-ICSI. Using spermatozoa obtained by PESA and IVF before RE-ICIS is a viable treatment for men with OA.     

Expectations for oocyte fertilization and embryo cleavage after whole sperm versus sperm head intracytoplasmic sperm injection

OBJECTIVE: To compare oocyte fertilization and embryo development after intracytoplasmic sperm injection (ICSI) with a whole sperm vs. a sperm head. DESIGN: Retrospective study. SETTING: Hospital-based IVF practice. PATIENT(S): Fifty-three women undergoing 54 IVF-embryo transfer plus ICSI procedures between January 1999 and June 2002. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Oocyte fertilization, zygote cleavage, and embryo stage after 72 hours of culture. RESULT(S): A significantly higher fertilization rate was observed using whole sperm (72.2%) than when using sperm heads (56.4%). Zygote cleavage rates for whole sperm vs. sperm head ICSI were 96.4% and 92.7%, respectively. Embryo cell stage after 72 hours of culture for whole sperm vs. sperm head ICSI was 6.5 +/- 2.1 cells and 5.6 +/- 1.8 cells, respectively. Embryo grade at this same time point was not different (2.3 +/- 1.0 and 2.5 +/- 0.9, respectively). CONCLUSION(S): The ICSI using whole sperm produces superior fertilization rates compared to ICSI using sperm heads, but once oocytes were fertilized, zygote cleavage rates were not different between the two sperm sources. Oocytes injected with a whole sperm produced embryos of higher cell stage but equivalent quality compared to oocytes injected with sperm heads. Therefore, having only sperm heads for use in ICSI should not be a deterrent to using this procedure.     

Computer-assisted oocyte morphometry before ICSI: correlation of oocyte measurements with fertilization and embryo development

The present study aimed to correlate morphometric parameters of the oocytes with the occurrence of fertilization following intracytoplasmic sperm injection (ICSI). In a prospective, controlled cohort design, women (n = 32) who were candidates for ICSI had oocytes (n = 258) collected and submitted to morphometric evaluation using the Cronus3 software program. The morphometric parameters obtained were oocyte diameter, perivitelline space width, zona pellucida thickness, and first polar body diameter. The median oocyte diameter was similar in cases in which fertilization occurred compared with those in which fertilization failed (75.2 and 75.9 μm, respectively; P = .218). The 2 groups also had similar measurements of perivitelline space, zona pellucida, and first polar body. However, the best quality zygotes identified by a morphological score resulted from oocytes with larger diameter (75.6 vs 74.0 μm; P < .01) and narrow perivitelline space (5.3 vs 7.1 μm; P < .01). Embryo development, as assessed by cleavage at second day of culture, was not significantly associated with oocyte morphometric parameters. These findings suggest that morphometric parameters of the oocytes do not correlate with the occurrence of fertilization following ICSI but may assist in selecting oocytes more likely to originate high-quality zygotes.     

Impact of sperm DNA fragmentation on the outcome of IVF with own or donated oocytes

A prospective study was performed to assess the impact of sperm DNA fragmentation on the outcome of IVF with own or donated oocytes. The study population included 178 couples (62 cycles of IVF, 116 of intracytoplasmic sperm injection (ICSI)) with own (n=77) and donor (n=101) oocytes. DNA fragmentation was evaluated by TdT (terminal deoxynucleotidyl transferase)-mediated dUDP nick-end labelling assay. Correlation between DNA damage to oocyte fertilization, embryo quality and clinical pregnancy, implantation and miscarriage rates was evaluated. DNA fragmentation was not related to fertilization rates in either IVF (r=0.08) or ICSI (r=-0.04) cycles. DNA fragmentation was similar in patients with <50% embryo utilization rate compared with ≥50%, in cancelled and in embryo transfer cycles and in miscarriages and in successful deliveries. Moreover, DNA fragmentation was similar in pregnant and non-pregnant women as well as in IVF with own or donor oocytes. In the multivariable analysis, the odds ratio of DNA after controlling by age was 1.0. Using a 36% sperm fragmentation threshold, results did not vary. It is concluded that DNA damage was not related to outcomes of IVF or ICSI with own or donor oocytes.     

Cytogenetic analysis of uncleaved oocytes after intracytoplasmic sperm injection

Purpose This work analyzes the causes of cleavage failure after intracytoplasmic sperm injection (ICSI) and the effect of the procedure on the chromosomes of the oocytes.Methods Ninety-seven uncleaved oocytes from 39 patients with severe male infertility or repeated IVF failure were fixed; 79 were analyzable. We checked the decondensation stage of spermatozoa nucleus and the chromosomal abnormalities of the oocytes.Results Among the fixed oocytes, the spermatozoa nucleus was present in 97% of the cases, and it was undecondensed in 89% of the cases, showing no evolution at all. A low rate (2.6%) of premature chromosome condensation (PCC) of the spermatozoa and a low rate (2.5%) of female diploïdy were observed. Among the oocytes that could be karyotyped, we observed a high rate (45%) of chromosome breakage.Conclusion ICSI fertilization failure was due mostly to the complete lack of evolution of the spermatozoa nucleus. Oocyte selection before ICSI seemed to lower the PCC rate. The high rate of oocyte chromosomal breakage rate has to be confirmed.     

Sperm retention site and its influence on cleavage rate and early development following intracytoplasmic sperm injection

Background : Intracytoplasmic sperm injection (ICSI) has risen to the forefront of reproductive technology. In the present study, the location of the sperm injection was noted, and a prospective study was conducted to evaluate the effect of the sperm retention site on cleavage rates and embryo quality after ICSI. Methods : This study involved 336 ICSI patients (age 27–44; average 37.4) where 1545 oocytes were observed. An oocyte was divided into nine sites and the sperm retention site was observed microscopically after injection. The polar body was placed at either the twelve or six o’clock position. The injection pipette was introduced at the three o’clock position and oolemma rupture was ascertained by mild suction. The main outcome measures were the relationship of sperm remaining in position in the oocyte to fertilization rate and embryo quality. Results : When the injection pipette was introduced at the three o’clock position, about 80% of the sperm remained in the center or left of center. The fertilization rate was significantly lower (p < 0.05) when the sperm remained near the site of introduction. Embryo quality was not significantly affected by the sperm retention site. Conclusions : About 12–14% of the spermatozoa remained near the introducing position, and in these cases the fertilization rate was low. However, once fertilization occurred, the sperm retention site had minimal impact on embryo quality. Injecting sperm near the spindle site may improve embryo quality.     

Relationship of the Human Cumulus-Free Oocyte Maturational Profile with In Vitro Outcome Parameters After Intracytoplasmic Sperm Injection

Purpose: We investigated whether the human oocyte maturational profile at the removal of cumulus/corona cells affects the fertilization rate and subsequent embryo quality after intracytoplasmic sperm injection. Methods: A total of 1011 oocytes from 150 cycles was included in this retrospective analysis. Cumulus-free oocytes that were in prophase or metaphase I of meiosis at the removal of cumulus/corona cells were incubated in vitro until they reached metaphase II (in vitro-matured oocytes) and were then immediately injected with a single spermatozoa. Oocytes that were in metaphase II at the removal of cumulus/corona cells (MII oocytes) received sperm injection after 3–4 hr of preinjection incubation. Results: The fertilization rate of the MII oocytes was significantly higher than that of in vitro-matured oocytes (81 vs 62%; P < 0.001). The cleavage rates were similar in the two groups (MII oocytes, 94%; in vitro-matured oocytes, 91%). However, MII oocytes had significantly higher percentages of good-quality embryos (grade 1–3 embryos, 87 vs 58%, P < 0.001) and embryos with high cumulative embryo scores (score 10–32 embryos, 62 vs 33%, P < 0.001). The mean cumulative embryo score of MII oocytes after fertilization was also higher than that of in vitro-matured oocytes (12.1 ± 3.8 vs 8.8 ± 3.4; P = 0.014). Conclusions: MII oocytes that extruded the first polar body at the removal of cumulus/corona cells had better fertilization rates and embryo morphology than in vitro-matured oocytes that extruded the first polar body following the removal of cumulus/corona cells and in vitro culture.