The human embryo following biopsy on day 5 versus day 3: viability, ultrastructure and spindle/chromosome configurations.

RESEARCH QUESTION: Are there any differences in viability, spindle abnormalities and mitochondrial and other organelle structures amongst embryos biopsied on day 3 versus day 5 before and after vitrification? DESIGN: A total of 240 day 3 biopsied embryos that developed to blastocysts but were rejected for transfer following preimplantation genetic testing for monogenic/single gene defects (PGT-M) (n = 115) or for aneuploidies (PGT-A) (n = 125) were divided into two groups: (i) 120 blastocysts treated for viability, spindle/chromosome configuration (SCC) analysis and transmission electron microscopy (TEM) analysis (fresh n = 20, n = 20, n = 20 and following vitrification/warming n = 20, n = 20, n = 20); (ii) 120 embryos were re-biopsied at the blastocyst stage and treated for viability, SCC and TEM analysis (fresh n = 20, n = 20, n = 20 and following vitrification/warming n = 20, n = 20, n = 20). Also, 60 vitrified blastocysts biopsied only on day 5 that were rejected for transfer following PGT-M (n = 6) or PGT-A (n = 54) were treated following warming for viability (n = 20), SCC (n = 20) and TEM analysis (n = 20). RESULTS: No differences were observed in SCC and ultrastructure between embryos biopsied on day 5 and day 3 but following vitrification higher numbers of abnormal spindles, distension of mitochondria, multivesicular bodies, lipofuscin droplets, altered cell junctions and occasionally excessive accumulation of glycogen granules were evident. The fresh day 3 biopsied group also had a lower incidence of damaged (propidium iodide-stained) cells compared with the fresh day 3+5 (P = 0.02) and the vitrified day 5 (P = 0.001) biopsied groups. CONCLUSIONS: Biopsies on day 5 and day 3 do not adversely affect embryo viability, SCC or ultrastructure, although following vitrification minimal embryo quality-dependent increases in spindle abnormalities and cell damage are observed.

Day-5 fresh embryo transfer is associated with superior clinical outcomes in oocyte donation cycles compared with day-3 embryo transfer.

OBJECTIVE: Τo compare clinical outcomes between day-5 (D5ET) and day-3 (D3ET) fresh embryo transfer in oocyte donation cycles. STUDY DESIGN: A retrospective analysis of prospectively collected cohort data was performed enrolling all participants in an oocyte donation program performed either D5ET or D3ET regarding the period from June 2006 to June 2018. Cycles were compared by the day of embryo transfer. Primary outcomes were the clinical pregnancy rate and live birth rate. Secondary outcomes were implantation rate, biochemical pregnancy rate, early miscarriage rate, and twin pregnancy rate. Outcomes were adjusted for covariates within study groups. RESULTS: A total of 8023 cycles meeting our inclusion criteria were analyzed. D5ET consisted of 4865 cycles and D3ET of 3158 cycles. The D5ET group had a significantly higher clinical pregnancy rate (p < .001), live birth rate (p = .004), implantation rate (p < .001), and twin pregnancy rate (p = .02) than the D3ET group. Accordingly, biochemical pregnancy rate (7.4% vs. 5.1%, p < .001) and early miscarriage rate (4.1% vs. 3.2%, p = .04) were significantly higher in D3ET compared to the D5ET group. CONCLUSION: Οocyte donation cycles with fresh D5ET resulted in fewer embryos transferred, higher clinical pregnancy rates, and higher live birth rates compared to D3ET. Our findings are strongly favoring day-5 embryo transfer in oocyte donation cycles.

Viability assessment using fluorescent markers and ultrastructure of human biopsied embryos vitrified in open and closed systems.

RESEARCH QUESTION: Are there any differences in viability and ultrastructure amongst embryos biopsied on Day 5 versus Day 3 following vitrification in open and closed systems and compared to fresh embryos? DESIGN: One hundred human embryos (40 blastocysts biopsied on Day 5 and subsequently vitrified in open or closed systems and 60 Day 3 biopsied embryos that developed to blastocysts but were rejected for transfer following preimplantation genetic testing for monogenic/single gene defects and for aneuploidies were either treated fresh [n = 20] or vitrified [n = 40] in open or closed systems) and following warming and culture for 4 h were subjected to viability staining with carboxyfluorescein-diacetate succinimidylester/propidium iodide or processed for transmission electron microscopy. RESULTS: No statistically significant differences were observed in the viability of human biopsied embryos following vitrification in open and closed systems. Compared to fresh embryos, vitrified ones had a higher incidence of damage (propidium iodide-stained cells) irrespective of the vitrification method (P = 0.005). These damaged cells were more prominent in Day 5 biopsied blastocysts and mainly located at the position of cutting. Characteristic lipofuscin droplets (representative of apoptosis) and a higher number of vacuoles and distension of mitochondria were also more evident in vitrified embryos, although this was not statistically assessed. CONCLUSIONS: Vitrification in open and closed systems does not adversely affect the viability and ultrastructure of Day 5 and Day 3 biopsied embryos as revealed by the minimal yet statistically significant cell damage observed. This damage may be compensated by the embryos, which in their attempt to fully recover following vitrification, potentially enable 'rescue' processes to eliminate it.

Closed vs. Open Oocyte Vitrification Methods Are Equally Effective for Blastocyst Embryo Transfers: Prospective Study from a Sibling Oocyte Donation Program.

PURPOSE: To assess whether open and closed vitrification protocols are equally effective for sibling-oocyte cycles when performing blastocyst embryo transfers. MATERIALS AND METHODS: A prospective study was set up comparing the open and the closed vitrification techniques in oocyte recipients sharing sibling oocytes between 2014 and 2016. Sibling oocytes were randomly and equally assigned into the closed group (oocytes vitrified in a closed system) or the open group (oocytes vitrified in an open system). Intracytoplasmic sperm injection was performed on all cases. Embryo transfers were performed on day 5. Power analysis calculation showed that 94 cycles would be needed for each group in the study in order to achieve statistical significance at a 5% level with power 80%. RESULTS: The final number of donors included was 95. A total of 190 recipients matched with their donors were included in the study. There was no difference in the mean number of oocytes vitrified with the closed or the open system (8.26 ± 2.54 vs. 8.31 ± 2.57). No significant difference was observed between the 2 groups regarding survival rate, fertilization rate, cleavage rate, top-quality embryos on day 3, blastocyst rate, and top-quality blastocyst rate. Moreover, no statistically significant difference in the b-human chorionic gonadotropin-positive rate, clinical pregnancy rate per cycle, implantation rate, ongoing pregnancy rate, and live birth rate between closed and open groups. CONCLUSION: Οpen and closed vitrification protocols are equally effective for sibling-oocyte cycles.

Spindle and chromosome configuration analysis of human biopsied versus non-biopsied embryos by confocal laser scanning microscopy following vitrification.

SummaryThe aim of this study was to investigate the effects of zona drilling and biopsy on day 3 followed by vitrification on day 5 on the cytoskeleton and development of human embryos, by analysing survival rates and spindle and chromosome configurations by fluorescence and confocal laser scanning microscopy in human biopsied and non-biopsied embryos. In total, 98 human blastocysts (50 non-biopsied and 48 following biopsy on day 3) were vitrified on day 5 using either a commercial dimethyl sulphoxide (DMSO)-free vitrification kit or increasing concentrations of DMSO/EG (5%/5-10%/10-20%/20%). Following warming, the blastocysts were allowed to recover in culture for 24 h and were immunostained with α-tubulin, acetylated tubulin, and/or γ-tubulin antibodies in combination with 4',6-diamidino-2-phenylindole (DAPI). Labelled embryos were examined by both fluorescence and confocal laser scanning microscopy. The survival rates following warming (92% non-biopsied vs 83.3% biopsied) and the incidence of normal spindle chromosome configurations was not statistically different between the two groups (65.2% non-biopsied vs 59.2% biopsied, P>0.05). The incidence of spindle abnormalities including multipolarity, chromosome lagging, congression failure and chromosome bridging were also similar between the two groups (P>0.05). This study is the first to compare the incidence of cytoskeletal abnormalities in biopsied and non-biopsied human embryos following vitrification. We conclude that there was no significant difference in the survival rates and the incidence of spindle abnormalities between the two groups.

The impact of sperm DNA fragmentation on ICSI outcome in cases of donated oocytes.

PURPOSE: The aim of this study is to evaluate the sperm DNA fragmentation index (DFI) in oocyte donation cycles and correlate it with the sperm parameters, the male characteristics, the embryo quality and the outcome of intracytoplasmic sperm injection (ICSI). METHODS: A total of 150 couples participating in an oocyte donation program were included in the study. Sperm samples were assessed by conventional sperm analysis. DFI was evaluated using the Halosperm kit, a sperm chromatin dispersion test (SCD). RESULTS: The relations between DNA damage and epidemiological male factors (age, height, weight), standard semen parameters (concentration, total and forward motility, and morphology), and embryological and clinical parameters (fertilization rate, total blastocyst number, number of good quality blastocyst, clinical pregnancy) were analyzed. DFI was positively correlated with advanced male age (r = 0.23, p < 0.05) and negatively correlated with total sperm and forward motility (r = - 0.29, r = - 0.27, respectively; p < 0.05). DFI was not significantly correlated with pregnancy outcome in oocyte donation cycles (r = - 0.05, p > 0.05). When good quality blastocysts were chosen, a trend toward the development of good quality embryos was detected in the presence of a low DFI (r = - 0.20, p = 0.08). CONCLUSIONS: DFI does not significantly affect the outcome of ICSI in oocyte donation cycles. Even in cases of advanced paternal age that a high DFI resulted sperm DNA fragmentation seems not to adversely affect the final outcome.

Declining Sperm Counts or Rather Not? A Mini Review.

IMPORTANCE: Temporal global trends of sperm quality remain a matter of debate. OBJECTIVE: The aim of this study was to present a comprehensive review of studies reporting on sperm quality counts, summarize the main end points, and assess the main reasons for potential discrepancies. EVIDENCE ACQUISITION: An evidence-based review of PubMed and Scopus databases was performed regarding studies reporting on modification of sperm quality counts, independently of study character, study language, or date. RESULTS: Since the meta-analysis of Carlsen et al in 1992 (Br Med J 1992;305:609-613) that suggested an annual decline in sperm count of 1%, several reports confirmed the decline in sperm quality, whereas others disproved them, suggesting a slight increase or absence of change in sperm count. Such controversies may be attributed to geographical and time-related variability in sperm values and also to several confounding factors that influence the semen parameters. Intrinsic weaknesses of the studies include heterogeneity of subjects recruited, lack of adjustment for confounding factors, and samples that do not always represent the general population. CONCLUSIONS: No consensus exists on whether sperm counts actually decrease because studies' results are often controversial or inconclusive with methodological deficiencies. More prospective, large-scale, population based studies are needed in order to provide sound evidence of possible global trends in sperm count.

GnRH antagonist administered twice the day before hCG trigger combined with a step-down protocol may prevent OHSS in IVF/ICSI antagonist cycles at risk for OHSS without affecting the reproductive outcomes: a prospective randomized control trial.

PURPOSE: The purpose this study is to investigate whether a double antagonist dose (0.25 mg/12 h) administered the day before hCG trigger is effective in preventing ovarian hyperstimulation syndrome (OHSS) in GnRH antagonist IVF/intracytoplasmic sperm injection (ICSI) cycles at risk for OHSS. METHODS: This is a prospective randomized control study, conducted from November 2012 to January 2016. A total of 194 patients undergoing a IVF/ICSI GnRH antagonist cycle that were at risk of OHSS and chose to proceed with embryo transfer and avoid cycle cancellation or embryo cryopreservation were allocated into two groups. The inclusion criteria consisted of a rapid rise of oestradiol ≥ 3500 pg/ml combined with ≥ 18 follicles > 11 mm in diameter without any mature follicle > 16 mm, in any day of stimulation. Overall, 97 patients (intervention group A) received a double dose of GnRH antagonist (0.25 mg/12 h) the day before hCG while 97 patients (control group B) did not. Recombinant FSH administration was tapered to 100 IU/24 h the day of the allocation in both groups. RESULTS: Incidence of early-onset moderate/severe OHSS was significantly lower in intervention group A compared to control group B (0 vs 12.37%, P < 0.001). Clinical pregnancy rate per cycle (50.52 vs 42.27%, P = 0.249) was not significantly different between the two groups. Oestradiol (3263.471 ± 1271.53 vs 5233 ± 1425.17, P < 0.001), progesterone (0.93 ± 0.12 vs 1.29 ± 0.14, P < 0.001) and luteinizing hormone (1.42 ± 0.31 vs 1.91 ± 0.33, P < 0.001) were significantly lower in group A the day of the hCG triggering. CONCLUSION: The administration of a rescue double GnRH antagonist dose the day before hCG trigger may represent a safe alternative preventive strategy for early OHSS without affecting the reproductive outcomes. TRIAL REGISTRATION NUMBER: ISRCTN02750360.

Vitrification of Human Germinal Vesicle Oocytes: before or after In Vitro Maturation?

BACKGROUND: The use of immature oocytes derived from stimulated cycles could be of great importance, particularly for urgent fertility preservation cases. The current study aimed to determine whether in vitro maturation (IVM) was more successful before or after vitrification of these oocytes. MATERIALS AND METHODS: This prospective study was performed in a private in vitro fertilization (IVF) center. We collected 318 germinal vesicle (GV) oocytes from 104 stimulated oocyte donation cycles. Oocytes were divided into two groups according to whether vitrification was applied at the GV stage (group 1) or in vitro matured to the metaphase II (MII) stage and then vitrified (group 2). In the control group (group 3), oocytes were in vitro matured without vitrification. In all three groups, we assessed survival rate after warming, maturation rate, and MII-spindle/chromosome configurations. The chi-square test was used to compare rates between the three groups. Statistical significance was defined at P<0.05 and we used Bonferroni criterion to assess statistical significance regarding the various pairs of groups. The Statistical Package for the Social Sciences version 17.0 was used to perform statistical analysis. RESULTS: There was no significant difference in the survival rate after vitrification and warming of GV (93.5%) and MII oocytes (90.8%). A significantly higher maturation rate occurred when IVM was performed before vitrification (82.9%) compared to after vitrification (51%). There was no significant difference in the incidence of normal spindle/ chromosome configurations among warmed oocytes matured in vitro before (50.0%) or after (41.2%) vitrification. However, a higher incidence of normal spindle/chromosome configurations existed in the in vitro matured oocytes which were not subjected to vitrification (fresh oocytes, 77.9%). CONCLUSION: In stimulated cycles, vitrification of in vitro matured MII oocytes rather than GV oocytes seems to be more efficient. This approach needs to be verified in nonstimulated fertility preservation cases.

How does closed system vitrification of human oocytes affect the clinical outcome? A prospective, observational, cohort, noninferiority trial in an oocyte donation program.

OBJECTIVE: To evaluate whether is possible to vitrify oocytes in an aseptic (hermetically closed) fashion and maintain clinical results comparable with those of fresh oocytes. DESIGN: Prospective, observational, cohort, noninferiority trial. SETTING: Private in vitro fertilization center. PATIENT(S): One hundred eighty-four recipients of donated vitrified oocytes. INTERVENTION(S): Closed system vitrification. MAIN OUTCOME MEASURE(S): Pregnancy rate per cycle and clinical pregnancy rate per cycle. RESULT(S): No statistically significant differences were observed between two groups regarding the pregnancy rate per cycle (63.1% vs. 60.9%) or the clinical pregnancy rate per cycle (55.4% vs. 58.7%). Biochemical pregnancy rate was statistically significantly higher in the fresh group (7.6% vs. 2.2%). The mean number of embryos transferred was similar (2.0 ± 0.0 vs. 1.97 ± 0.3). Concerning embryologic data, there were no statistically significant differences regarding the fertilization, cleavage, top quality day-3 embryo, or blastocyst rates, whereas the top quality blastocyst rate on day 5 was statistically significantly higher in the fresh oocyte group (31.7% vs. 26.1%). CONCLUSION(S): Aseptically (in a closed system) vitrified oocytes show similar clinical efficiency compared with their sibling fresh oocytes.

GnRH antagonist versus long GnRH agonist protocol in poor IVF responders: a randomized clinical trial.

OBJECTIVE: To compare the efficacy of the long GnRH agonist and the fixed GnRH antagonist protocols in IVF poor responders. STUDY DESIGN: This was a randomized controlled trial performed in the Iakentro IVF centre, Thessaloniki, from January 2007 to December 2011, concerning women characterised as poor responders after having 0-4 oocytes retrieved at a previous IVF cycle. They were assigned at random, using sealed envelopes, to either a long GnRH agonist protocol (group I) or a GnRH antagonist protocol (group II). RESULTS: Overall 364 women fulfilled the inclusion criteria and were allocated to the two groups: finally 330 participated in our trial. Of these, 162 were treated with the long GnRH agonist protocol (group I), and 168 with the fixed GnRH antagonist protocol (group II). Numbers of embryos transferred and implantation rates were similar between the two groups (P=NS). The overall cancellation rate was higher in the antagonist group compared to the agonist group, but the difference was not significant (22.15% vs. 15.2%, P=NS). Although clinical pregnancy rates per transfer cycle were not different between the two groups (42.3% vs. 33.1%, P=NS), the clinical pregnancy rate per cycle initiated was significantly higher in the agonist compared to the antagonist group (35.8% vs. 25.6%, P=0.03). CONCLUSIONS: Although long GnRH agonist and fixed GnRH antagonist protocols seem to have comparable pregnancy rates per transfer in poor responders undergoing IVF, the higher cancellation rate observed in the antagonist group suggests the long GnRH agonist protocol as the first choice for ovarian stimulation in these patients.

History of endometriosis may adversely affect the outcome in menopausal recipients of sibling oocytes.

Due to the known adverse effect of endometriosis on gamete quality, it has always been difficult to demonstrate a direct effect of endometriosis on implantation. In order to eliminate these confounding effects, this prospective comparative study studied a population of menopausal recipients with and without endometriosis sharing sibling oocytes coming from the same donor. The aim was to understand the impact of endometriosis on implantation, pregnancy and live birth rates in menopausal recipients. A total of 240 menopausal recipients of donated sibling oocytes, were divided in two groups. Group I consisted of 120 recipients diagnosed with endometriosis and group II consisted of 120 controls. The implantation and pregnancy rates were significantly lower in the endometriosis group compared with the control group (23.81% versus 31.48%, P=0.019; 45.00% versus 58.33%, P=0.039, respectively). In oocyte donation cycles, a recipient's history of endometriosis might have a negative impact on implantation, pregnancy and live birth rates, even in menopausal women. Infertility in endometriosis may be due to poor oocyte quality or embryos with decreased ability to implant due to impaired fertilization. There are no conclusive data on the impact of endometriosis on implantation. The already-known adverse effect of endometriosis on gamete quality makes it more difficult to demonstrate a direct effect of endometriosis on implantation. In order to eliminate these confounding effects we studied a population of menopausal recipients with and without endometriosis sharing sibling oocytes coming from the same oocyte donor. The oocyte donation model was used in an attempt to understand whether the endometrium, the oocytes or both are affected by endometriosis. The aim of the present study was to understand the impact of endometriosis on implantation, pregnancy and live birth rates in menopausal recipients. A total of 240 menopausal recipients of donated sibling oocytes were divided into two groups. Group I consisted of 120 recipients diagnosed with endometriosis and group II consisted of 120 controls. The pregnancy and implantation rates were significantly lower in the endometriosis group compared to the control group (45.00% versus 58.33%, P=0.039) and (23.81% versus 31.48%, P=0.019) respectively. In oocyte donation cycles, a recipient's history of endometriosis might have a negative impact on implantation, pregnancy and live birth rates, even in menopausal women.

Injection of embryo culture supernatant to the endometrial cavity does not affect outcomes in IVF/ICSI or oocyte donation cycles: a randomized clinical trial.

OBJECTIVE: To evaluate whether intrauterine injection of embryo culture supernatant before embryo transfer has any impact on pregnancy and implantation rates. STUDY DESIGN: A total of 400 cycles, of which 200 IVF/ICSI and 200 oocyte donor (OD), were randomly assigned to have their uterine cavity injected (group I) or not (group II). Primary endpoints to be studied were pregnancy and implantation rates. RESULTS: Clinical pregnancy rate per transfer (47.87%, 90/188 versus 48.45%, 94/194) based on transvaginal scan findings at 7 weeks of gestation and implantation rate (25.6% versus 26.5%) were similar in the two groups. The day of embryo transfer, day 3 or day 5, did not affect the final outcome. CONCLUSION: Injection of embryo culture supernatant into the uterine cavity, 30 min before the embryo transfer on either day 3 or 5, neither improves nor adversely affects the pregnancy rate in IVF/ICSI or oocyte donation cycles.

Cytoskeletal analysis of human blastocysts by confocal laser scanning microscopy following vitrification.

BACKGROUND: Vitrification of human blastocysts is being used increasingly to cryopreserve supernumerary embryos following IVF. In this study, we investigate the effects of aseptic vitrification on the cytoskeleton and development of human blastocysts, by analysing survival rates and spindle and chromosome configurations by fluorescence and confocal laser scanning microscopy. METHODS: A total of 55 fresh blastocysts and 55 day 5 dimethylsulphoxide/ethylene glycol vitrified blastocysts, which were allowed to remain in culture for 24 h post-warming, were rapidly fixed in ice cold methanol, and immunostained with an a-tubulin antibody to visualize microtubules in combination with antibodies against acetylated tubulin (to visualize spindles, poles and mid bodies), gamma tubulin (to identify spindle poles) and 4(6-diamidino-2-phenylindole) to visualize DNA. RESULTS: In total, 213 spindles were analysed in the control (fresh) group of which 183/213 (85.9%) were normal, 20/213 (9.4%) were abnormally shaped, 9/213 (4.2%) were multipolar and 1/213 (0.5%) was monopolar. A total of 175 spindles were analysed in the vitrified group, of which 120/175 (68.6%) were normal, 39/175 (22.3%) were abnormally shaped, 10/175 (5.7%) were multipolar and 6/175 (3.4%) were monopolar. The incidence of multipolar spindles was similar in the two groups, but the level of abnormally shaped spindles, often associated with chromosome lagging, or congression failure, was significantly higher in the vitrified group compared with the fresh group (P< 0.05). CONCLUSIONS: The high survival rate following thawing and the large proportion of normal spindle/chromosome configurations suggests that vitrification at the blastocyst stage on Day 5 does not adversely affect the development of human embryos and the ability of spindles to form and continue normal cell divisions. However, there was a significantly higher incidence of abnormal spindles in the vitrified group compared with the fresh group, notably of spindles with a focused and an unfocused pole as well as chromosome bridging and disorganized middle spindle fibres at telophase. Further investigation is warranted to elucidate the mitotic stages that are more vulnerable to damage during vitrification, the fate of the abnormal spindles and any potential effects that may be reflected on the chromosomal constitution of the developing blastocysts.

Cryptic sperm defects may be the cause for total fertilization failure in oocyte donor cycles.

In conventional IVF cycles with total fertilization failure, rescue intracytoplasmic sperm injection (ICSI) performed 24h after insemination has yielded poor results. However, when ICSI is used, total fertilization failure is a rare event. The aim of the present study is to investigate the degree of sperm contribution to fertilization failures using the egg-sharing model in oocyte donor cycles. The study included only the oocyte donor cycles of sibling oocytes with total fertilization failure in at least one of the matched recipients. Oocytes from 49 oocyte donor cycles were equally shared among 98 recipients undergoing conventional IVF. Due to total fertilization failure in half of the recipients, rescue ICSI was carried out. Compared with the conventional IVF only group, the rescue ICSI group had a lower pregnancy rate (30.61% versus 71.43%), clinical pregnancy rate (28.57% versus 67.35%) and ongoing pregnancy rate (28.57% versus 63.27%) (all P<0.01). Cryptic sperm defects in apparently normal spermatozoa may be the cause of total fertilization failure, indicating the need for simple routine tests to detect them.

GnRH antagonists and endometrial receptivity in oocyte recipients: a prospective randomized trial.

The effect that gonadotrophin-releasing hormone (GnRH) antagonists exert on endometrial receptivity has not yet been elucidated. GnRH antagonists might directly affect oocytes, the embryo and/or the endometrium. The aim of this study was to investigate the direct effect of GnRH antagonists on the endometrium in oocyte donation cycles. In an oocyte donation programme, oocytes from each donor (n = 49), stimulated with gonadotrophins and a GnRH antagonist, were equally shared between two different matched recipients. Recipients were randomly allocated to either receive a GnRH antagonist concomitant to donor during their endometrial priming with oestradiol (group I, n = 49) or to solely continue with their endometrial preparation (group II, n = 49). Pregnancy rate was 55.1% in group I and 59.1% in group II. Implantation rate was 26.1% in group I and 24.4% in group II. Endometrial thickness was also similar between the two groups on the day of human chorionic gonadotrophin injection to the donor. In conclusion, GnRH antagonist administration during the proliferative phase at a dose of 0.25 mg per day does not appear to adversely affect endometrial receptivity in oocyte recipients.

Low-dose human chorionic gonadotropin during the proliferative phase may adversely affect endometrial receptivity in oocyte recipients.

The effect of low-dose human chorionic gonadotropin (hCG) administration in the proliferative phase of oocyte recipients was investigated in a prospective randomized trial. Sibling oocytes from the same donor were shared at random among two different recipients. In group I oocyte recipients received 750 IU of hCG every three days concomitant to endometrial preparation with estradiol until hCG injection to the donor, whereas in group II recipients received no hCG during endometrial priming with estradiol. Endometrial thickness was significantly lower in group I compared with group II, although similar endometrial thickness was detected during the mock cycle. Pregnancy rates were significantly lower in group I than in group II (13.6% vs. 45.4%, p<0.05). Implantation rates were also significantly lower in group I (1.7% vs. 22.4%, p<0.01). The study was discontinued prematurely for ethical reasons when 22 cycles were completed, as pregnancy rates were very low in group I. In conclusion, hCG administration in the proliferative phase might directly affect endometrial proliferation and receptivity.

Comparison of effects of zona drilling by non-contact infrared laser or acid Tyrode's on the development of human biopsied embryos as revealed by blastomere viability, cytoskeletal analysis and molecular cytogenetics.

Use of a non-contact infrared laser (IRL) or acid Tyrode's for zona drilling before embryo biopsy was compared by assessing blastomere viability using various fluorescent markers or culture of the single biopsied blastomere, and, by cytoskeletal and molecular cytogenetic analysis of the biopsied embryos following culture to the blastocyst stage. There was no significant difference in the proportion of biopsied embryos that showed no damage in both the biopsied blastomere and in the remaining embryo (acid Tyrode's: 75% versus IRL: 68%), or in the proportion of single biopsied blastomeres that divided in culture (P > 0.05). However, single biopsied blastomeres from laser drilled embryos showed a greater tendency to form miniblastocysts. The proportion of laser or acid Tyrode's biopsied embryos that reached the blastocyst stage by day 6 was similar, although evident earlier (day 5) in the laser biopsied embryos. Spindle abnormalities at the blastocyst stage included tripolar and tetrapolar spindles, but their incidence was not significantly different from controls. In addition, no significant difference was observed in the incidence of chromosomal abnormalities and mosaicism between the two groups. It is concluded that using an IRL at a safe working distance does not cause adverse immediate or longer term effects on the development of human biopsied embryos, although damage can occur if drilling within this distance is unavoidable. Acid Tyrode's drilling can also cause damage, and tended to retard blastocyst development.