The impact of the source of spermatozoa used for ICSI on pronuclear morphology.
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BACKGROUND: The aim of this prospective study was to find out whether the source of spermatozoa used for intracytoplasmic sperm injection (ICSI) has an impact on the morphological features of pronucleate zygotes, which make up the basis of a pronuclear scoring system for the selection of the most viable embryos for transfer. METHODS AND RESULTS: The study group consisted of 194 two pronucleate (2PN) ICSI zygotes, of which 144 originated from ejaculated (ES) and 50 from testicular spermatozoa (TS). At 18 h postinjection, 2PN zygotes were assessed for pronuclear alignment, polarity in nucleoli and cytoplasmic appearance; all of which were found to exhibit similar patterns of distribution between the ES and TS groups (P = not significant). At 25 h, the presence of first cleavage was similar for both groups; 11% of zygotes in the ES and 10% of those in the TS group underwent early cleavage (P = not significant). At 48 h, a quality score was obtained for cleaving embryos by multiplying the number of blastomeres with the grade of the embryo. Pronuclear scoring in both groups of spermatozoa correlated with embryo quality score at 48 h postinjection. There was a trend for a higher incidence of early cleavage and a lower incidence of pronuclear arrest with better pronuclear scoring embryos for both types of spermatozoa. CONCLUSION: The morphological features of pronucleate zygotes at 18 h after microinjection with ES and TS are similar to each other. (+info)
Vitrification of mouse oocytes using closed pulled straws (CPS) achieves a high survival and preserves good patterns of meiotic spindles, compared with conventional straws, open pulled straws (OPS) and grids.
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BACKGROUND: We modified the loading of pulled straws into a new closed system, called closed pulled straws (CPS) for holding oocytes for vitrification. The morphological survival, dynamics of meiotic spindles, and fertilization in vitro of vitrified oocytes using CPS were compared with conventional straws, open pulled straws (OPS), and grids. METHODS: Surviving oocytes were stained for spindles and chromosomes after 1, 2 and 3 h incubations, and compared with controls. The capacity of fertilization and embryonic cleavage were examined in vitro. RESULTS: The survival rates of the CPS (79%) and straw (77%) groups were significantly higher (P < 0.05) than the OPS (63%) and grid (39%) groups. At a 1h incubation, vitrified oocytes of four groups had significantly fewer normal spindles than controls (P < 0.05). The straw group was inferior to the others in spindle morphology (P < 0.05). After a 3 h incubation, recovery of vitrified oocytes with normal spindles was significantly improved in all groups (P < 0.05). The percentages of fertilization and blastocyst formation of vitrified oocytes after a 1 h incubation was significantly lower than controls (P < 0.05), but they were improved after 2 or 3 h incubations (P < 0.05). CONCLUSIONS: Oocytes vitrified using CPS, OPS or grids could lessen spindle injuries and expedite recuperation. The survival using OPS or grids is lower. Sufficient culture time for recovery of meiotic spindle would be imperative for fertilization events of vitrified oocytes. CPS has the advantages of achieving a high survival and preserving good spindles. (+info)
The effect of pronuclear morphology on embryo quality parameters and blastocyst transfer outcome.
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BACKGROUND: Embryo quality may be accurately assessed as early as the pronuclear zygote phase, as shown in recent studies. However, it is not known whether good quality zygotes are destined to become good quality cleavage stage embryos and blastocysts. METHODS: In this retrospective study, 86 intracytoplasmic sperm injection-embryo transfer cycles were studied where each available embryo was scored from the zygote until the blastocyst stage. Embryonic normality parameters such as pronuclear pattern, early cleavage, cleavage stage embryo grade, the presence of embryos with > or =8 cells on day 3 and blastocyst quality were recorded. Embryo transfer was undertaken at the blastocyst stage and the outcome was studied according to the pronuclear pattern exhibited by the zygotes. RESULTS: Embryos that showed an ideal pronuclear pattern (0 PN pattern) cleaved earlier and faster and resulted in better quality cleavage stage embryos and blastocysts. The incidence of blastocyst formation was 72% in zygotes showing a 0 PN pattern, compared with 12.7% in zygotes with double pronuclear abnormality. Higher implantation and pregnancy rates were obtained when at least one blastocyst derived from a 0 PN pattern zygote was included in the set of embryos to be transferred. CONCLUSIONS: Our results indicate that the pronuclear pattern of the zygote is closely related to blastocyst formation and quality. Blastocysts derived from 0 PN zygotes have a higher potential for implantation. (+info)
Improvement of quality of oocytes collected in the autumn by enhanced removal of impaired follicles from previously heat-stressed cows.
(68/708)
The fertility of dairy cows decreases during the summer and remains low during the cooler autumn although the animals are no longer under heat stress. The aim of this study was to characterize a delayed effect of summer heat stress on oocyte quality in the autumn and to improve oocyte quality by enhanced removal of follicles damaged during the previous summer. Lactating cows (n = 16) were subjected to heat stress during the summer. In autumn, ovarian follicles (3-7 mm in diameter) were aspirated by an ultrasound-guided procedure during four consecutive oestrous cycles. Follicles were aspirated from control cows on day 4 and from treated cows on days 4, 7, 11 and 15 of each oestrous cycle. All cows received PGF(2alpha) and GnRH injections on days 19 and 21, respectively, and maintained cyclicity, as indicated by plasma progesterone concentrations. On day 4 of each cycle, the oocytes recovered were examined morphologically, matured and activated in vitro, and cultured for 8 days. In cycle 1 (early October) both groups showed low percentages of grade 1 oocytes, cleavage, four- and eight-cell embryos, morulae and parthenogenetic blastocysts. Subsequently, the number of grade 1 oocytes increased earlier (cycle 2) in treated than in control cows (cycle 3; P < 0.05). The cleavage rate in the control group remained relatively low throughout (32-58%), whereas in the treated group it increased from 40% (cycle 1) to 75% (cycles 3 and 4; P < 0.05). The number at each stage of embryo development increased slightly but remained low throughout in the control group, whereas in the treated group significant (P < 0.05) increases of all stages were observed in cycles 3 and 4. The results show a delayed effect of summer heat stress on oocyte quality and embryo development in the autumn. Enhanced removal of the impaired cohort of follicles led to earlier emergence of healthy follicles and high quality oocytes in the autumn. (+info)
Insect segmentation: Genes, stripes and segments in "Hoppers".
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Recent work has revealed that orthologues of several segmentation genes are expressed in the grasshopper embryo, in patterns resembling those shown in Drosophila. This suggests that, despite great differences between the embryos, a hierarchy of gap/pair-rule/segment polarity gene function may be a shared and ancestral feature of insect segmentation. (+info)
Outcome of ICSI using fresh and cryopreserved-thawed testicular spermatozoa in patients with non-mosaic Klinefelter's syndrome.
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BACKGROUND: Recently, intracytoplasmic sperm injection (ICSI) of testicular spermatozoa retrieved surgically from patients with non-mosaic Klinefelter's syndrome resulted in several deliveries. The aim of this study was to evaluate the outcome of ICSI using fresh and cryopreserved-thawed testicular spermatozoa in these patients. METHODS AND RESULTS: Following informed consent regarding the genetic risks of their potential offspring, mature testicular spermatozoa were found in five out of 12 (42%) patients who underwent testicular sperm extraction, and ICSI was performed while excess tissue was cryopreserved. The mean age of the patients was 28.7 +/- 3.6 (range 23-36 years). Their baseline FSH was elevated (mean 38.3 +/- 11.4; range 22-58 mIU/ml). All patients had small testicles of 2-4 ml in volume. The outcome of ICSI using fresh or cryopreserved-thawed testicular spermatozoa during five cycles in each group, was compared. No statistical significant difference was found in the two pronuclear fertilization rate (66 versus 58%), embryo cleavage rate (98 versus 90%) and embryo implantation rate (33.3 versus 21.4%) for fresh or cryopreserved sperm accordingly. The clinical outcome after using fresh testicular sperm included two singleton pregnancies (one delivered and one ongoing) and a triplet pregnancy resulting in a twin delivery (after reduction of an 47,XXY embryo). After using cryopreserved-thawed testicular spermatozoa, two pregnancies were obtained resulting in one delivery of twins and one early spontaneous abortion. CONCLUSIONS: Outcome of ICSI using cryopreserved-thawed testicular spermatozoa of patients with non-mosaic Klinefelter's syndrome is comparable with that following the use of fresh spermatozoa. The genetic implications for the future offspring should be explained to the patients. (+info)
Laser assisted immobilization of spermatozoa prior to intracytoplasmic sperm injection in humans.
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BACKGROUND: The conventional method of immobilization of spermatozoa prior to intracytoplasmic sperm injection (ICSI) is mechanical breakage of the tail by pressing it against the bottom of the injection dish. METHODS: This prospective self-controlled study was set up to evaluate the potential of a non-contact 1.48 microm wavelength diode laser in terms of immobilization. In addition, the fertilization rate and further development potential of such zygotes were investigated. The patients included in our study (n = 60) had oestradiol concentrations >2000 pg/ml, and thus a relatively high number of MII oocytes could be expected. Approximately half the oocytes were injected with laser treated spermatozoa (n = 262, study group) and the other half with mechanically immobilized spermatozoa (n = 252, control group). RESULTS: No significant differences between the two groups in terms of fertilization rate, early cleavage or blastocyst formation were observed. However, time required for identification, aspiration and injection of a potential spermatozoa was significantly shorter in the laser immobilized sperm group (P < 0.001). CONCLUSIONS: The application of a non-contact diode laser for sperm immobilization prior to ICSI is a potentially useful alternative to the conventional mechanical approach. (+info)
Early embryo cleavage is a strong indicator of embryo quality in human IVF.
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BACKGROUND: In order to decrease multiple birth rates without decreasing birth rates overall, it is important to increase the capability of selecting the most optimal embryos for transfer. It has been shown that human embryos which cleave early, i.e. complete the first mitotic division within 25-27 h post insemination, provide higher pregnancy and implantation rates. METHODS AND RESULTS: In this prospective study, an evaluation of 10 798 scored embryos showed that early cleavage resulted in a significantly higher proportion of good quality embryos compared with late cleavage (62.5 versus 33.4%, P < 0.0001). When examining both day 2 and day 3 transfers together, early-cleaving embryos (306 transfers) gave rise to significantly higher rates of pregnancy/transfer (40.5 versus 31.3%, P = 0.0049), implantation (28.0 versus 19.5%, P = 0.0001) and birth/ongoing pregnancy (34.3 versus 24.0%, P = 0.0009) than did late-cleaving embryos (521 transfers). A stepwise logistic regression of all data showed that the total number of good quality embryos and female age were independent predictors of both pregnancies and birth. For intracytoplasmic sperm injection (ICSI) embryos, early cleavage was found to be an independent predictor of birth. CONCLUSIONS: Early embryo cleavage is a strong biological indicator of embryo potential, and may be used as an additional embryo selection factor for ICSI embryos. (+info)