Analysis of the human zona pellucida during culture: Correlation with diagnosis and the preovulatory hormonal environment

Purpose: The objective of this study was to analyze sequentially the human zona pellucida changes in an in vitro fertilization program as it relates to several variables. Methods: The zona pellucida thickness was measured daily in zygotes and cleavage-stage embryos on a Nikon inverted microscope equipped with Hoffman modulation contrast optics, using an ocular micrometer. A total of 512 embryos from 96 patients was evaluated. Results: There was a highly significant direct correlation between zona thickness and preovulatory estradiol and basal day 3 FSH levels (P < 0.02 andP < 0.0006, respectively). This relationship showed a rapid reversal following 48 hr of culture; embryos from patients with the highest FSH levels had thinner zonae prior to transfer (P < 0.0007). The zonae from patients with unexplained infertility were thicker (19.4 ± 2.7 μm) than those from patients with endometriosis (17.7 ± 2.2 μm), tubal (17.5 ± 2.4 μm), or male-factor infertility (16.4 ± 2.7 μm) (P < 0.0001) on the first day of culture. Conclusions: We hypothesize that the thickness of the human zona pellucida is influenced by the preovulatory hormonal environment and diagnosis. These factors should be considered as part of the embryo quality evaluation prior to transfer or when assessing the possibility of using assisted hatching. More studies are needed to understand the factors regulating the thickness of the human zona pellucida.     

Mechanistic insights into the effect of nanoparticles on zebrafish hatch

Aquatic organisms are susceptible to waterborne nanoparticles (NP) and there is only limited understanding of the mechanisms by which these emerging contaminants may affect biological processes. This study used silicon (nSi), cadmium selenide (nCdSe), silver (nAg) and zinc NPs (nZnO) as well as single-walled carbon nanotubes (SWCNT) to assess NP effects on zebrafish (Danio rerio) hatch. Exposure of 10 mg/L nAg and nCdSe delayed zebrafish hatch and 100 mg/L of nCdSe as well as 10 and 100 mg/L of uncoated nZnO completely inhibited hatch and the embryos died within the chorion. Both the morphology and the movement of the embryos were not affected, and it was determined that the main mechanism of hatch inhibition by NPs is likely through the interaction of NPs with the zebrafish hatching enzyme. Furthermore, it was concluded that the observed effects arose from the NPs themselves and not their dissolved metal components.     

辅助孵化与培养时间对冻融胚胎移植结局的影响

目的分析胚胎冻融后体外培养时间以及采用激光辅助孵化(AH)技术对临床妊娠率的影响。方法126名患者,130个冻融胚胎移植周期,按照是否实施AH技术分为AH组和非AH组,又按胚胎解冻后的不同培养时间进一步将两者分为2h(A/A’组)、1d(B/B’组)及2d组(C/C’组)。冻融胚胎采用慢速冷冻-快速解冻方法。冻融后的胚胎均置囊胚培养液培养2h、1d或2d,自1.48μm双极二氧化碳激光系统(ZILOS-tk)安装后的冻融胚胎均施行AH技术。结果AH组培养2h、1d、2d三组临床妊娠率之间有显著性差异(P<0.05);在培养1d与2d组中,实施AH与非AH组的临床妊娠率之间亦有显著性差异(P<0.05)。结论应用激光AH技术以及胚胎冻融后培养至桑椹胚或囊胚时行胚胎移植均显著提高冻融胚胎移植的临床妊娠率。     

Does assisted hatching improve implantation rates after in vitro fertilization or intracytoplasmic sperm injection in all patients? A prospective randomized study

Purpose: Preliminary data from some research centers indicate that assisted hatching might be of value to increase embryo implantation rate in the human, at least in selected cases. It is not clear, however, whether this technique would be of benefit for all patients undergoing an embryo transfer. We therefore performed a prospective randomized study to evaluate the effect of assisted hatching on the implantation rate in our in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) program. Methods: In total, 120 couples undergoing an embryo transfer were randomized between two groups: in one group no assisted hatching was performed (AH–), whereas in the other group the embryos selected for transfer were subjected to partial zona dissection (PZD) immediately prior to the transfer (AH+). Using a computer-generated minimization procedure, patients were allocated to one of the two groups according to four preselected criteria: the number of embryos transferred, the cumulative score of transferred embryos, the age of the patient, and the use of ICSI. Results: Pregnancy and implantation rates in the AH+ and AH– groups were, respectively, 42.1 versus 38.1% and 17.9 versus 17.1%. Conclusions: From our data we conclude that assisted hatching through partial zona dissection prior to embryo transfer does not improve pregnancy and embryo implantation rates in unselected patients undergoing IVF or ICSI.Presented in part at the IXth World Congress on In Vitro Fertilization and Alternate Assisted Reproduction, Vienna, Austria, April 3–7, 1995.     

A Study Failing to Determine Significant Benefits from Assisted Hatching: Patients Selected for Advanced Age, Zonal Thickness of Embryos, and Previous Failed Attempts

Purpose: Pregnancy and implantation rates after mechanical assisted hatching (AH) in patients aged 38 years, with embryos 15 m in zonal thickness and two or more failed attempts, were assessed at two infertility centers using fresh and frozen embryo transfer (FET) cycles. Methods: AH was performed on 3-day-old embryos. Spare embryos cryopreserved at the two-pronucleus stage were subjected to AH after 2 days of culture and transferred to artificially prepared uteri. Results: In fresh cycles, no significant differences in pregnancy rates (clinical and ongoing) and implantation rates were observed between the AH and the controls for all three selected patient groups (Centers 1 and 2). In FET cycles, AH tended to give poor results for 38 year olds (clinical pregnancy rates of 0 and 5.0% with AH vs 13.3 and 16.7% for controls at Centers 1 and 2, respectively). With AH, embryos with thick zonae implanted to the same extent as those in the control group and achieved pregnancies for patients with multiple failures (four to six attempts for some) in both fresh and FET cycles. Conclusions: AH failed to show significant benefits in all three patient groups. A larger study group may confirm the effects of AH on frozen/thawed embryos and outcomes for multiple failure cases.     

泪道激光联合迪可罗眼膏治疗泪道阻塞的研究

目的:探讨泪道激光联合迪可罗眼膏治疗泪道阻塞的临床疗效.方法:采用泪道激光泪道成形术联合泪道内分别注入迪可罗眼膏和生理盐水,共治疗泪道阻塞患者106例(120只眼).随访观察6个月.结果:迪可罗组6个月冲洗通畅率为93.3%,生理盐水组保持通畅率为70.0%,两组疗效差异有显著性(x2=10.91,P＜0.01).结论:采用泪道激光泪道成形术联合泪道内注入迪可罗眼膏,是成功率较高的治疗泪道阻塞的方法之一.     

丝光绿蝇室内种群孵化动态观察

目的观察丝光绿蝇室内种群的孵化特征。方法每天观察丝光绿蝇室内种群第7代及第8代幼虫孵化数量,未孵出数量,计算每天的孵化率,并进行分析。结果在产卵期前期,孵出的第7代及第8代幼虫数量相对较多,孵化率相对较高且稳定。后期孵出的幼虫数量相对较少,孵化率较低。结论丝光绿蝇室内种群产卵前期幼虫孵化率较高且稳定,转种应在前期进行。     

Chemical removal of zona pellucida versus laser assisted hatching after repeated failures of assisted reproductive technology

Background and Aims:  To evaluate outcomes after zona pellucida removal by pronase or laser assisted hatching in women with repeated assisted reproduction failures.
Methods:  Of 389 procedures (January 2004 to November 2005), 203 control cycles had an intact zona, 116 cycles had chemical removal of the zona and 70 cycles had laser assisted hatching. Rates of pregnancy, implantation and abortion were compared, and pregnancy rate was secondarily evaluated for fresh or frozen-thawed blastocysts.
Results:  Pregnancy rates were 33.5% (68/203) for controls, 29.3% (34/116) for chemical removal and 30.0% (21/70) for laser. Implantation rates were 24.8% (68/274) for controls, 21.8% (34/156) for chemical removal and 30.0% (21/105) for laser. There were no significant differences among groups. Abortion rates were 15.6% (10/64) for controls, 13.9% (5/36) for chemical removal and 14.3% (3/21) for laser. No difference was observed by blastocyst type for control or laser assisted hatching cycles. In the chemical removal group, both pregnancy and implantation rates were higher for frozen-thawed blastocysts than for fresh blastocysts. (41.5% vs 13.2% and 30.7% vs 11.1%, respectively).
Conclusions:  Assisted hatching did not show a significant benefit. Chemical zona pellucida removal might increase pregnancy rates for frozen-thawed blastocysts. (Reprod Med Biol 2006; 5: 263–267)     

Assisted hatching--a meta-analysis of randomized controlled trials

Purpose : To conduct a meta-analysis of randomized controlled trials (RCTs) on assisted hatching. Methods : One hundred sixty-five studies were retrieved from the literature, but only 13 of them fitted our selection criteria. The meta-analysis was conducted using the RevMan software with the Peto-modified Mantel–Haenszel method. Results : Assisted hatching increases the pregnancy [OR (±95% CI) = 2.51 (1.91–3.29)], implantation [OR (±95% CI) = 2.38 (1.87–3.03)], and ongoing pregnancy rates [OR (±95% CI) = 2.65 (1.85–3.79)] significantly in poor prognosis patients undergoing IVF or ICSI. For patients with repeated IVF failures, the OR (±95% CI) were 2.84 (1.99–4.06) for pregnancy, 2.53 (1.85–3.47) for implantation, and 3.51 (2.12–5.82) for ongoing pregnancy rates, in favor of assisted hatching. Conclusions : Assisted hatching increases the pregnancy, implantation, and ongoing pregnancy rates significantly in patients with a poor prognosis undergoing IVF or ICSI, particularly those with repeated failures.