Improve Embryo Quality Research Articles

“Physiologic ICSI”: Hyaluronic acid (HA) favors selection of spermatozoa without DNA fragmentation and with normal nucleus, resulting in improvement of embryo quality

To evaluate the role of hyaluronic acid (HA) for sperm selection before intracytoplasmic sperm injection (ICSI). Three prospective studies. Private assisted reproduction center in Italy. Study 1: 20 men. Study 2: 15 men. Study 3: 206 couples treated with ICSI on a limited number of oocytes per patient (1-3) in accordance with Italian IVF law. Study 1: determination of sperm DNA fragmentation of HA-bound spermatozoa versus spermatozoa in polyvinylpyrrolidone (PVP). Study 2: assessment of nuclear morphology of HA-bound spermatozoa versus spermatozoa in PVP. Study 3: randomized study comparing conventional PVP-ICSI to ICSI in which the spermatozoa are selected for their capacity to bind to HA (HA-ICSI). Study 1: sperm DNA fragmentation rate. Study 2: sperm nucleus normalcy rate according to motile sperm organellar morphology examination criteria. Study 3: fertilization, embryo quality and development, and implantation and pregnancy. Spematozoa bound to HA show a significant reduction in DNA fragmentation (study 1) and a significant improvement in nucleus normalcy (study 2) compared with spermatozoa immersed in PVP. Furthermore, injection of HA-bound spermatozoa (HA-ICSI) significantly improves embryo quality and development (study 3). Hyaluronic acid may optimize ICSI outcome by favoring selection of spermatozoa without DNA fragmentation and with normal nucleus. Furthermore, HA may also be used to speed up the selection of spermatozoa with normal nucleus during intracytoplasmic morphologically selected sperm injection (IMSI).

A new real-time morphology classification for human spermatozoa: a link for fertilization and improved embryo quality

To understand the correlation between normalcy of the sperm, fertilization, and early embryo development, and to establish a detailed classification scoring scale for the individual spermatozoon with the highest predictive fertilizing potential in real time during intracytoplasmic sperm injection (ICSI). A retrospective and analysis. Laboratory Drouot. 27 couples with male factor infertility referred for ICSI treatment. Before ICSI, motile spermatozoa were scored after aspiration. Oocyte fertilization, embryo development and morphology, outcome of scored motile injected spermatozoa. Our suggested formula is (Normal head score = 2) + (Lack of vacuole score = 3) + (Normal base score = 1) = (Total score = 6) for a morphologic "normal top" spermatozoon, calculated with the major criteria affecting the outcome of ICSI. We take into account the normalcy of head size and shape, the base of the head, and the lack of vacuoles. Our scoring of three classes of injected spermatozoa revealed a statistically significant difference in fertilization rate: 39 out of 46 (84%), 94 out of 128 (73%), and 27 out of 44 (61%), respectively. Our examination of the contribution of maternal age in correlation to sperm score revealed a distinction between oocytes originating from women younger than 30 years and oocytes from women aged 30 years and older. Our suggested classification provides allows the best spermatozoon to be chosen for ICSI, particularly for oocytes from women aged 30 years and older.

Optimizing IVF with sexed sperm in cattle

Sperm-sorting by flow cytometry separates X-sperm from Y-sperm with an accuracy as high as 90% or more. This technology offers farmers and the livestock industry the potential to nearly double productivity, by producing the desired sex to optimize breeding programs. Sorting speed and fertility variation of sorted sperm, however, remain limiting factors for widespread application, particularly in traditional AI programs. Alternatively, in vitro fertilization is a feasible and efficient means to increase the fertilization efficiency of sex-sorted sperm in cattle. Procedures to increase fertilization rate and improve embryo quality include optimizing heparin concentrations for semen of each bull, reducing fertilization drop size to increase sperm concentration, use of fructose instead of glucose in culture media, and use of vitrification protocols with extremely rapid cooling and warming rates.

Reduced oxygen concentration during day 3-5 of embryo culture does not result in improved embryo quality

Reduced oxygen concentration during day 3-5 of embryo culture does not result in improved embryo quality

L-carnitine improves embryo quality and increases blastocyst development rate in couples undergoing ICSI

OBJECTIVE: Stabilization of the mitochondrial membrane leads to increase in the supply of energy to the organelle and protect the cell from apoptotic death. L-Carnitine (LC) is a potent antioxidant that increases the supply of energy to the organelles, stabilizes the mitochondrial membranes, and protects cells against DNA damage. The objective of our study was to examine if supplementing the culture media with LC improves embryo quality and the %BDR in couples undergoing ICSI.DESIGN: Prospective clinical study.MATERIALS AND METHODS: We included those patients who had more than 15 fertilized oocytes and were not interested in embryo cryopreservation at day 3. A total of 617 oocytes obtained from 38 infertile couples (12 with male factor infertility, 11 female factor infertility and 15 combined male and female factor infertility) were fertilized by ICSI. Embryos (2PN) were classified into two groups:, Group A (n = 131): embryos were incubated in ISM1 cleavage culture medium (Medicult, Denmark) supplemented with 0.3mg/ mL LC and Group B (n = 147): embryos incubated in ISM1 cleavage culture medium without LC. On day 3, embryos in both groups were transferred to ISM2 extended culture medium (Medicult Denmark) with LC (group A) or without LC (group B). Only grade 1 embryos were allowed for incubation to day 5 and blastocyst development rate (%BDR) was assessed.RESULTS: LC at 0.3mg/mL concentration significantly improves the quality of embryos at day 3 and the %BDR at day 5 compared with the untreated group (P<0.001 and P<0.001 respectively) (Table 1).Table 1Comparison of % grade 1 embryos at day 3 and %BDR at day 5 between Groups A and Group BParameterGroup A (%)Group B (%)∗P value <0.05 was considered significant by Wilcoxon test. Values are median (25th and 75th percentile). P value% Grade I embryos (day 3)100.0 (100.0, 100.0)60.0 (50.0, 71.4)<0.001% BDR (day 5)75.0 (60.0, 100.0)50.0 (33.3, 66.7)<0.001∗ P value <0.05 was considered significant by Wilcoxon test. Values are median (25th and 75th percentile). Open table in a new tab OBJECTIVE: Stabilization of the mitochondrial membrane leads to increase in the supply of energy to the organelle and protect the cell from apoptotic death. L-Carnitine (LC) is a potent antioxidant that increases the supply of energy to the organelles, stabilizes the mitochondrial membranes, and protects cells against DNA damage. The objective of our study was to examine if supplementing the culture media with LC improves embryo quality and the %BDR in couples undergoing ICSI. DESIGN: Prospective clinical study. MATERIALS AND METHODS: We included those patients who had more than 15 fertilized oocytes and were not interested in embryo cryopreservation at day 3. A total of 617 oocytes obtained from 38 infertile couples (12 with male factor infertility, 11 female factor infertility and 15 combined male and female factor infertility) were fertilized by ICSI. Embryos (2PN) were classified into two groups:, Group A (n = 131): embryos were incubated in ISM1 cleavage culture medium (Medicult, Denmark) supplemented with 0.3mg/ mL LC and Group B (n = 147): embryos incubated in ISM1 cleavage culture medium without LC. On day 3, embryos in both groups were transferred to ISM2 extended culture medium (Medicult Denmark) with LC (group A) or without LC (group B). Only grade 1 embryos were allowed for incubation to day 5 and blastocyst development rate (%BDR) was assessed. RESULTS: LC at 0.3mg/mL concentration significantly improves the quality of embryos at day 3 and the %BDR at day 5 compared with the untreated group (P<0.001 and P<0.001 respectively) (Table 1).

In vitro culture under physiologic oxygen concentration improves blastocyst yield and quality: a prospective randomized survey on sibling oocytes

A prospective randomized study was carried on sibling oocytes in which human gametes and embryos were cultured at physiologic (6% CO(2) + 5% O(2) + 89% N(2)) condition from insemination to day 6 or at atmospheric (6% CO(2) in air) condition until day 3 and at physiologic environment afterward. The results showed that physiologic oxygen concentration throughout culture period improved total blastocyst yield and day 5 embryo quality.

Short gamete co-incubation during in vitro fertilization decreases the fertilization rate and does not improve embryo quality: a prospective auto controlled study

Evaluate the effect of short gamete incubation on fertilization rate and embryo quality. A prospective study has been performed. Two thousand five hundred and forty seven sibling oocytes from 240 couples undergoing IVF attempts were allocated to a short (1 h) or a standard (18 h) insemination procedure. Diploid fertilization rate (two pronuclei, 2PN), polyspermy (>2PN) and embryo quality were compared. The fertilization rate was statistically lower in the short insemination group compared to the standard insemination one (64.9% and 70.1%; P = 0.039), with a similar polyspermy rate observed between the two groups. A slight, but non significant, increase was observed concerning good embryo quality rate in the short insemination group when compared to the standard insemination, both at day 2 (60.1 vs. 58.1%; P = 0.06) and day 3 (53.2 vs. 48.5%; P = 0.22). This new study highlights that a 1 h gamete exposure decreases the fertilization rate and does not improve embryo quality compared with a standard 18 h insemination procedure.

Long Chain Fatty Acids of Diet as Factors Influencing Reproduction in Cattle

Cattle are fed moderate amounts of long chain fatty acids (FA) with the objective to enhance lactation and growth; however, recent interest on lipid feeding to cows has focused on reproduction, immunity and health. Increasing the caloric density of the ration by fat feeding has generally improved measures of cow reproduction, but when milk yield and body weight losses were increased by fat supplementation, positive effects on reproduction were not always observed. Feeding fat has influenced reproduction by altering the size of the dominant follicle, hastening the interval to first postpartum ovulation in beef cows, increasing progesterone concentrations during the luteal phase of the oestrous cycle, modulating uterine prostaglandin (PG) synthesis, and improving oocyte and embryo quality and developmental competence. Some of these effects were altered by the type of FA fed. The polyunsaturated FA of the n-6 and n-3 families seem to have the most remarkable effects on reproductive responses of cattle, but it is not completely clear whether these effects are mediated only by them or by other potential intermediates produced during rumen biohydrogenation. Generally, feeding fat sources rich in n-6 FA during late gestation and early lactation enhanced follicle growth, uterine PG secretion, embryo quality and pregnancy in cows. Similarly, feeding n-3 FA during lactation suppressed uterine PG release, and improved embryo quality and maintenance of pregnancy. Future research ought to focus on methods to improve the delivery of specific FA and adequately powered studies should be designed to critically evaluate their effects on establishment and maintenance of pregnancy in cattle.

Buthionine sulfoximine (BSO)-mediated improvement in cultured embryo quality in vitro entails changes in ascorbate metabolism, meristem development and embryo maturation

Applications of buthionine sulfoximine (BSO), an inhibitor of GSH (reduced glutathione), which switches the cellular glutathione pool towards the oxidized form GSSG, positively influences embryo quality by improving the structure of the shoot apical meristem and promoting embryo maturation, both of which improve the post-embryonic performance of the embryos. To investigate the mechanisms underlying BSO-mediated improvement in embryo quality the transcript profiles of developing Brassica napus microspore-derived embryos cultured in the absence (control) or presence of BSO were analyzed using a 15,000-element B. napus oligo microarray. BSO applications induced major changes in transcript accumulation patterns, especially during the late phases of embryogenesis. BSO affected the transcription and activities of key enzymes involved in ascorbate metabolism, which resulted in major fluctuations in cellular ascorbate levels. These changes were related to morphological characteristics of the embryos and their post-embryonic performance. BSO applications also activated many genes controlling meristem formation and function, including ZWILLE, SHOOTMERISTEMLESS, and ARGONAUTE 1. Increased expression of these genes may contribute to the improved structural quality of the shoot poles observed in the presence of BSO. Compared to their control counterparts, middle- and late-stage BSO-treated embryos also showed increased accumulation of transcripts associated with the maturation phase of zygotic embryo development, including genes encoding ABA-responsive proteins and storage- and late-embryogenic abundant (LEA) proteins. Overall these transcriptional changes support the observation that the BSO-induced oxidized glutathione redox state allows cultured embryos to reach both morphological and physiological maturity, which in turn guarantees successful regeneration and enhanced post-embryonic growth.

Effects of melatonin and undernutrition on the viability of ovine embryos during anestrus and the breeding season

This study examined the effects of melatonin and level of nutrition on embryo yield during anestrous and breeding season. Adult Rasa Aragonesa ewes were assigned randomly to one of the four treatment groups in two experiments using a 2 × 2 × 2 factorial design. Individuals were treated (+MEL) or not treated (−MEL) with a subcutaneous implant of melatonin for 42 d (Melovine ®, CEVA) and fed 1.5 (control, C) or 0.5 (low, L) times the daily maintenance requirements for 20 d. Ewes were mated at oestrus (Day = 0) and embryos were recovered on Day 5. Level of nutrition and melatonin supplements did not have a significant effect on ovulation rate or the number of recovered ova per ewe in the Reproductive Season (RS) and the Anestrous Season (AS). During the RS, undernutrition reduced the number of viable embryos per ewe (C: 1.1 ± 0.2; L: 0.6 ± 0.2; P < 0.05); however, the number of viable embryos per ewe in the L+MEL group (0.2 ± 0.15) was significantly lower than it was in the L, C+MEL and C groups (0.9 ± 0.3, 1.2 ± 0.3, 1.0 ± 0.4, respectively; P < 0.05). In the AS, nutrition did not have a significant effect on the number of viable embryos per ewe, although melatonin supplements might have improved rates slightly. Embryo viability rate (% viable embryos/embryos recovered) was unaffected by melatonin supplements or level of nutrition in the RS and the AS. Season had a strong effect on the number of viable embryos per functional corpus luteum among ewes in the L+MEL group, only (RS: 0.2 ± 0.1; AS: 0.6 ± 0.2; P < 0.05). In conclusion, undernutrition impaired the viability of sheep embryos in the RS, particularly among ewes that were given melatonin supplements subcutaneously, but melatonin appeared to improve embryo quality in the AS, which suggests that the mechanisms involved in the interactive effects of melatonin and nutrition on embryo development are influenced by season.

Set up of a serum-free culture system for bovine embryos: Embryo development and quality before and after transient transfer

It is well known that serum in culture medium negatively affects blastocyst quality. The objective of this work was to develop and test a serum-free culture medium which could improve embryo quality, measured by the resistance to freezing, lipid and glutathione content of the resulting blastocysts, as well as the ability of the blastocysts to elongate after transient transfer to recipient cows. In a first experiment we showed that adding a mixture of insulin, transferrin and selenium to serum-free Synthetic Oviduct Fluid medium (SOF-ITS) improved embryo development and quality. In the second experiment, the addition of BSA to SOF-ITS further improved blastocyst development. Moreover, a reduction in lipid content of morulae was observed in SOF-ITS-BSA by comparison with morulae cultured with serum (SOF-FCS). The resistance to freezing measured by hatching rates 24h post-thawing was also improved for blastocysts with a diameter between 160 and 180 microm cultured in SOF-ITS-BSA by comparison to those produced with serum. In order to evaluate the redox potential of the embryos, reduced glutathione content (GSH) was evaluated both before and after cryopreservation. A significant decrease in glutathione was observed after freezing, whatever the culture medium, but no difference was observed between culture conditions. Transient transfers were performed and elongated D-13 embryos were recovered. Elongation was more pronounced and the embryonic disk more often visible in embryos cultured in SOF-ITS-BSA than in embryos cultured with FCS. In conclusion, the serum-free system we developed to produce in vitro bovine embryos meets the developmental and qualitative requirements for a large-scale use.

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.

Addition of Alpha-Tocopherol to Culture Medium Improves the Quality and Cryosurvival of Nuclear-Transferred Ovine Embryos

The aim of this study was to reconstruct and cryopreserve somatic cell nuclear transferred (SCNT) ovine embryos and evaluate the effect of alpha-tocopherol on blastocyst development and subsequent cryosurvival of the SCNT embryos. The alpha-tocopherol (100 microg/ml) was added into culture medium for the SCNT embryos, the yield and total cell numbers of blastocysts were determined and the apoptosis incidences of the blastocysts were evaluated using the TUNEL assay. The blastocysts from the alpha-tocopherol and untreated groups were then frozen-thawed, and their cryosurvival was assessed by in vitro culture for 48 h. The results showed that there were no significant differences in blastocyst yield (26.3 vs. 22.3%) and total cell number (68.2 vs. 64.3) between the alpha-tocopherol and untreated groups. However, addition of alpha-tocopherol to the culture medium significantly decreased the apoptotic cell number (3.4 vs. 5.5) and significantly increased the cryosurvival of SCNT blastocysts (66.8 vs. 50.7%). In conclusion, addition of alpha-tocopherol to SCNT embryo culture medium was beneficial for improving embryo quality by decreasing the apoptotic blastocyst cell number and improving the tolerance of the embryos to cryopreservation.

Effect of sperm chromatin integrity on the embryo quality following ICSI

DNA cytometry could differentiate damaged (sub-haploid) sperm from mature condensed haploid sperm, while aniline blue (AB) test indicates deficient DNA protamination. AB test can differentiate between healthy (non-stained) and non-healthy (stained) sperm chromatin. The aim of our study was to evaluate and compare sperm chromatin status using these two techniques with the embryo quality in infertile couples undergoing ICSI for male factor infertility. Prospective study. Semen samples from 42 infertile men with no female factor infertility. Routine semen analysis was done according to the WHO guidelines (1999). An aliquot of semen was used for ICSI procedure. Embryos were scored for morphological appearance. Pregnancy test was done 2 week after the embryos transfer. Sperm quality was assessed by DNA cytometry and Aniline blue staining. Good quality embryos showed significantly lower percentage of sub-haploid sperm compared to poor embryo quality group (P value = 0.02) (see Table).TableComparison of sperm chromatin structure in good vs. poor quality embryos∗P<0.05 considered significant by the Student's t test. Open table in a new tab ∗P<0.05 considered significant by the Student's t test. Embryo quality after fertilization in ICSI can be affected by the sperm chromatin fragmentation. Aniline blue staining is unable to differentiate the sperm that will result in good equality embryos. Selecting sperm with higher sperm chromatin integrity will help in the improvement of embryo quality after ICSI.

A case control study evaluating autologous endometrial coculture (AECC) as an effective tool for young patients (age

Young women with multiple failed IVF cycles and poor ovarian reserve are generally given a grim prognosis for IVF success. CC of embryos with monolayers of AECC has been shown to improve outcome for patients with multiple implantation failures after IVF-ET. Presumably, this effect is mediated through the production of trophic factors expressed by these helper cell lines. Earlier studies have demonstrated improved embryo quality in patients utilizing AECC. In this study, we analyzed the effectiveness of AECC in improving pregnancy rates in 207 cycles of IVF-ET in women with multiple failed IVF cycles and poor ovarian reserve.

Effects of Granulosa Cell Mitochondria Transfer on the Early Development of Bovine Embryos In Vitro

The objective of this study was to determine the effect of exogenous mitochondria obtained from granulosa cells on the development of bovine embryos in vitro. We classified cumulus oocyte complexes (COCs) as good (G)- and poor (P)-quality oocytes based on cytoplasmic appearance and cumulus characteristics, and assessed mtDNA copy numbers in the G and P oocytes with real-time polymerase chain reaction (PCR). The mitochondria were isolated by fractionation and suspended in mitochondria injection buffer (MIB). Part one of the experiment consisted of the following treatments: (1) G-oocytes + sperm, (2) P-oocytes + mitochondria + MIB + sperm, (3) P-oocytes + MIB + sperm, and (4) P-oocytes + sperm. In part 2, oocytes were parthenogenetically activated. The treatments were: (1) G-oocytes, (2) P-oocytes + mitochondria + MIB, (3) P-oocytes + MIB, and (4) P-oocytes alone. The results indicated a significant difference in mtDNA copy number between G (361 113 +/- 147 114) and P (198 293 +/- 174 178) oocytes (p < 0.01). The rates of morula, blastocyst, and hatched blastocysts derived from P-oocytes + mitochondria were similar to those of G-oocytes, but significantly higher than P-oocytes without exogenous mitochondria in both the ICSI and parthenogenetic activation experiments. We found no difference in blastomere numbers between G-oocytes and P-oocytes + mitochondria in either experiment, but blastomere numbers in these two groups were significantly higher than in P-oocyte groups without exogenous mitochondria. These data suggest that mtDNA content is very important for early embryo development. Furthermore, the transfer of mitochondria from the same breed may improve embryo quality during preimplantation development.

Embryo production and quality of Holstein heifers and cows supplemented with β-carotene and tocopherol

The hypothesis was that the intramuscular injection (i.m.) of β-carotene associated to tocopherol improves cow ( n = 86) and heifer ( n = 91) embryo production and quality. Time of estrus was synchronized in animals with an ear implant with 3 mg of norgestomet associated with an i.m. injection of 6 mg of norgestomet and 10 mg of estradiol valerate (CRESTAR ®, Intervert International B.V., Boxmeer, Holland) and superovulated by 8 i.m. FSH/LHp injections (400 IU-heifers and 500 IU-cows) in decreasing concentrations at 12 h intervals. Animals were inseminated 12 and 24 h after observed onset of estrus and embryos recovered 7 days later. Animals were randomly allocated to one of three treatments: (1) vegetable oil vehicle (control), (2) 800 mg of β-carotene and 500 mg of tocopherol (T800) and (3) 1200 mg of β-carotene and 750 mg of tocopherol (T1200). Supplemental injections were given at the day norgestomet implants were inserted and at first superovulatory injection. An index (Embryo Quality Index or EQI) was proposed to more precisely evaluate embryo quality (excellent*1 + good*2 + regular*3 + poor*4 + degenerate*5 + unfertilized ova*5)/total. There was an interaction between physiological stage (heifer or cow) and treatment on EQI ( P = 0.01) and on the proportion of viable embryos ( P = 0.03), where both variables were improved in T1200 cows, but not in heifers. The average EQI for heifers and cows in control, T800 and T1200 were 2.6 ± 0.3 and 3.6 ± 0.3; 2.5 ± 0.3 and 3.6 ± 0.3; 2.9 ± 0.3 and 2.7 ± 0.3, respectively. The average total number of viable embryos was greater ( P = 0.01) in supplemented cows (3.5 ± 1.1; 5.4 ± 1.4 and 7.5 ± 1.2 in control, T800 and T1200, respectively), but less ( P = 0.01) in heifers (7.5 ± 1.2; 5.6 ± 1.2 and 4.0 ± 1.1 in control, T800 and T1200, respectively). Supplementation injections of β-carotene associated to tocopherol improved embryo quality in superovulated Holstein cows, in the present experimental conditions and may be advantageous in similar embryo production systems. However, at dosages applied in the present experiment, this treatment should not be recommended for nuliparous heifers.

Regulation of Gene Expression in Bovine Blastocysts in Response to Oxygen and the Iron Chelator Desferrioxamine1

Low (2%) oxygen conditions during postcompaction culture of bovine blastocysts improve embryo quality and are associated with small increases in the expression of glucose transporter 1 (SLC2A1), anaphase promoting complex (ANAPC1), and myotrophin (MTPN), suggesting a role for oxygen in the regulation of embryo development, mediated through oxygen-sensitive gene expression. However, bovine embryos, to at least the blastocyst stage, lack detectable levels of the key regulator of oxygen-sensitive gene expression, hypoxia-inducible 1 alpha (HIF1A), while the less well-characterized HIF2 alpha protein is readily detectable. Here we report that other key HIF1 regulated genes are not significantly altered in their expression pattern in bovine blastocysts in response to reduced oxygen concentrations postcompaction-with the exception of lactate dehydrogenase A (LDHA), which was significantly increased following 2% oxygen culture. Antioxidant enzymes have been suggested as potential HIF2 target genes, but their expression was not altered following low-oxygen culture in the bovine blastocyst. The addition of desferrioxamine (an iron chelator and inducer of HIF-regulated gene expression) during postcompaction stages significantly increased SLC2A1, LDHA, inducible nitric oxide synthase (NOS2A), and MTPN gene expression in bovine blastocysts, although development to the blastocyst stage was not significantly affected. These results further suggest that expression of genes, known to be regulated by oxygen via HIF-1 in somatic cells, is not influenced by oxygen during preimplantation postcompaction bovine embryo development. Oxygen-regulated expression of LDHA and SLC2A1 in bovine blastocysts suggests that regulation of these genes may be mediated by HIF2. Furthermore, the effect of a reduced-oxygen environment on gene expression can be mimicked in vitro through the use of desferrioxamine. These results further support our data that the bovine blastocyst stage embryo is unique in its responsiveness to oxygen compared with somatic cells, in that the lack of HIF1-mediated gene expression reduces the overall response to low (physiological) oxygen environments, which appear to favor development.

Prospective evaluation of the optimal time for selecting a single embryo for transfer: day 3 versus day 5

To determine the best day for the selection and transfer of a single embryo, a prospective, randomized study was undertaken that compared the ongoing pregnancy rate (PR) after single embryo transfer (SET) on day 3 with that after single blastocyst transfer (SBT) on day 5. Our results show an overall significantly higher PR after SBT (32.8%) compared with SET (23.2%), and a PR of 40.8% after SBT versus 25.6% after excellent-quality embryos became available.

HOME ABOUT THIS JOURNAL CONTACT THIS JOURNAL CURRENT ISSUE ADVANCED VIEW ARCHIVE EDITORIAL BOARD Clinical use of Pentoxifylline for Freeze-Thawed Spermatozoa not Improve Embryo Quality

HOME ABOUT THIS JOURNAL CONTACT THIS JOURNAL CURRENT ISSUE ADVANCED VIEW ARCHIVE EDITORIAL BOARD Clinical use of Pentoxifylline for Freeze-Thawed Spermatozoa not Improve Embryo Quality