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PubMed2002

Human peripheral blood mononuclear cells (PBMC) in early pregnancy promote embryo invasion in vitro: HCG enhances the effects of PBMC.

BACKGROUND: The aim of this study was to investigate the role of peripheral blood mononuclear cells (PBMC) in embryo invasion at the implantation site and to estimate the effect on PBMC function of human chorionic gonadotrophin (HCG) that is secreted from the human embryo. METHODS AND RESULTS: The effect of PBMC on the invasiveness of murine embryos was examined using an invasion assay. PBMC obtained from women in early pregnancy (5-9 weeks gestation) significantly enhanced both spreading of murine embryos on Matrigel and invasion beneath the gel. These effects were greater than those of PBMC obtained from non-pregnant women in the secretory phase (cycle day 16-24) and the control (in the absence of PBMC). When PBMC obtained from non-pregnant women were incubated with recombinant HCG (10 IU/ml) for 2 days and were subjected to invasion assay using murine embryos, PBMC treated with HCG significantly promoted both spreading and invasion of murine embryos as compared with the non-treated PBMC. On the other hand, embryo outgrowth was not affected by HCG in the absence of PBMC, showing no direct effect of HCG on embryo invasion. CONCLUSION: This study indicated that PBMC from pregnant women promoted murine embryo invasion in vitro and this effect of PBMC was enhanced by HCG. These findings suggest that PBMC at the implantation site are activated by HCG secreted from the embryo, following which PBMC regulate embryo invasion.

Animals↗
PubMed1988

Hyperstimulation: the need for cryopreservation of embryos.

Successful application of in-vitro fertilization (IVF), zygote intra-Fallopian transfer (ZIFT) and gamete intra-Fallopian transfer (GIFT) requires ovarian hyperstimulation for the maturation of multiple follicles. To control the risk of multiple pregnancies, the number of gametes (GIFT) or embryos (IVF, ZIFT) replaced is limited to three. For the supernumerary embryos resulting from IVF, ZIFT or GIFT, the strategy is cryopreservation for a later transfer. Cryopreservation was performed using either dimethylsulphoxide or 1,2-propanediol as a cryoprotective agent. Embryos were frozen either in the pronucleate stage with 1,2-propanediol or in the multicellular stage with dimethylsulphoxide or 1,2-propanediol. Survival after thawing was scored for both cryoprotective agents as a function of the developmental stage of the embryo and the embryonic quality. Evaluation of survival after thawing was performed on the basis of morphological intactness of the 1-cell pronucleate embryo or of the blastomeres of multicellular embryos. For pronucleate stage embryos, the use of 1,2-propanediol resulted in a 60% survival after thawing. For 2-cell stage embryos the survival was similar for dimethylsulphoxide and 1,2-propanediol. Later stage embryos survived better when dimethylsulphoxide was the cryoprotectant. For all stages, embryo quality before freezing was a crucial factor in survival after thawing. The pregnancy rate (12.2%) was similar for the two cryopreservation protocols. In conclusion, the choice of an appropriate cryoprotective agent can increase the survival after thawing when embryos are of good quality before freezing.

Cryoprotective Agents↗
PubMed2006

Does PGD for aneuploidy screening change the selection of embryos derived from testicular sperm extraction in obstructive and non-obstructive azoospermic men?

BACKGROUND: An increased incidence of aneuploid embryos has been recently described from azoospermic men. The aim of this study was to assess if embryo selection on day 5, based on morphological criteria, would be different from the selection based on PGD for aneuploidy screening (AS) in couples undergoing ICSI for male azoospermia. METHODS: Sixty-two cycles of testicular sperm extraction (TESE)-ICSI with PGD-AS were included in the analysis. Two embryologists, blinded to the PGD-AS results, retrospectively reviewed the available embryology data from day 5 embryos and selected one, two or three embryos to be transferred. These results were compared with the selected embryos based on PGD-AS. RESULTS: A total of 39 cycles from non-obstructive azoospermia (NOA) and 23 cycles from obstructive azoospermia (OA) were retrospectively analysed. If single embryo transfer (SET) had been performed, in 64.8% of the NOA cycles and 54.5% of the OA cycles, no difference in embryo choice would have occurred compared to PGD-AS and in 10.8 and 36.6% of the cycles, respectively, an aneuploid embryo would have been chosen. If double ET (DET) had been performed, in 72.9% of the NOA cycles and 86.5% of the OA cycles, no difference in embryo choice would have occurred compared to PGD-AS and in 2.7 and 4.5% of the cycles, respectively, an aneuploid embryo would have been chosen. If triple ET (TET) had been performed, the outcome would have been the same as for DET. DISCUSSION: Our results suggest that under the terms of an SET policy, the performance of PGD-AS in azoospermia would result in a higher chance of success, as the possibility of selecting a euploid embryo is enhanced.

Adult↗
PubMed1996

Undocumented embryos: do not trash them, FISH them.

Pronuclei formation is routinely assessed 16-20 h after oocyte insemination in in-vitro fertilization (IVF). Occasionally, the pronuclei disappear before this time, rendering them as 'undocumented'. Since the number of pronuclei detected is used to distinguish normal from abnormal embryos in the context of ploidy, the diploidy of undocumented embryos is questionable, and therefore they are routinely discarded. The introduction of fluorescent in-situ hybridization (FISH) technology allows the assessment of ploidy status in undocumented embryos that continue to cleave to form blostomeres. In this study, we used FISH to analyse the chromosomal status of 23 undocumented embryos obtained from 10 patients. Biopsied blastomeres were fixed and probed for five chromosomes (X, Y, 13, 18, 21). Diploidy was confirmed in 13 (57%) embryos while the remaining 10 embryos displayed various chromosomal anomalies. Six of the diploid embryos were transferred subsequently to the patients. One ongoing pregnancy was achieved following transfer of an undocumented, analysed embryo, which was already cleaved when assessed 20 h after insemination. We suggest that accelerated dismantling of the pronuclear membrane and subsequent cleavage do not necessarily indicate abnormal chromosomal content and may result in normal pregnancy. In a patient with a small number of embryos, FISH may be used to ascertain diploidy of undocumented embryos, thereby increasing the number of available embryos for transfer.

Blastomeres↗
PubMed1987

Human embryo cryopreservation, extrinsic and intrinsic parameters of success.

Freezing and thawing (F - T) was applied to 490 early human embryos using propanediol as cryoprotectant. The survival rate of embryos frozen with propanediol alone did not exceed 31% (26/83). The combination of propanediol and sucrose, however, significantly increased the percentage of surviving (248/407 = 61%) and intact (188/407 = 46%) embryos and seemed to enhance embryo viability as suggested by the implantation rate (14.5 versus 8%) without, however, any statistical significance. Embryo survival, but not viability, was correlated with morphological features, whereas neither the age of embryos (1, 2 or 3 days post-insemination) nor the segmentation stage (regular or intermediate) were involved in F - T ability. Thirty-eight F - T embryos implanted when replaced in utero, representing 8% of all F - T embryos and 14% of the F - T replaced embryos. The pregnancy rate per transfer reached 19% (35/185) and was identical to the pregnancy rate per transfer of fresh embryos (253/1149 = 22%). In oocyte donation, too, embryo freezing did not impair the pregnancy rate (25%). In spontaneous cycles, synchronous transfer gave better results than asynchronous transfers (20 versus 10%), but spontaneous cycles had no significant advantage (16% pregnancy/transfer) as compared to stimulated (26%) and artificial (27%) cycles.

Blastomeres↗
PubMed1993

Embryonic morphology and rate of implantation of human embryos following co-culture on bovine oviductal epithelial cells.

A study was undertaken to evaluate embryonic development and establish pregnancies with human embryos after in-vitro culture in two different systems. Treatment A consisted of culturing zygotes in serum-supplemented human tubal fluid culture medium (HTF). Treatment B consisted of culturing zygotes on a monolayer of bovine oviductal epithelial cells with HTF. At the time of embryo replacement, embryos in treatment B had 4.11 blastomeres present, which was greater (P < 0.05) than the 3.81 present for embryos in treatment A. In addition, the cellular fragmentation rate for treatment A embryos was 1.10, which was greater (P < 0.05) than the fragmentation rate of 0.38 for embryos within treatment B. The incidence of ongoing pregnancy was higher after replacement of co-cultured embryos (treatment B) (43%) than replacement of conventionally cultured embryos (treatment A) (29%). The implantation rate per embryo increased (P < 0.05) from 11.5 to 18.4% after co-culture. In treatment B the proportion of 'spare' embryos developing to expanded blastocysts was 58.5%, which was greater (P < 0.05) than the blastocyst development rate of 29.3% observed for embryos within treatment A.

Animals↗
PubMed2003

Possible expansion of "Window of Implantation" in pseudopregnant mice: time of implantation of embryos at different stages of development transferred into the same recipient.

Blastocyst implantation and successful establishment of pregnancy require delicate interactions between the embryo and maternal environment. It is believed that the growth of transferred embryos of different ages is synchronized during preimplantation development and that such embryos are implanted in the uterus at the same time. To define the time of synchronization for developing embryos of different ages, embryos at two different stages of development were transferred separately into the oviducts of the same recipient. We then examined the subsequent development of the embryos at various time intervals after transfer. Pronucleus (PN) stage eggs were transferred separately to the right or left oviduct of recipients on Day 0, while eight-cell embryos (8C) were transferred to the other oviduct. For 8C, 5%, 63%, and 74% of transferred embryos were implanted in the uterus at 42, 66, and 90 h posttransfer, respectively. In contrast, none of the transferred PN was implanted until 90 h posttransfer. At 90 h posttransfer, 59% of the PN had successfully implanted. Histological examination revealed that developmental stage of the embryos in both groups synchronized around 162 h posttransfer, even though the implantation was accelerated in 8C compared with PN. Our results indicate that embryos of advanced stage transferred to the oviduct implant in the uterus in advance of younger embryos and that the uterine development is synchronized at the neural plate, presomite stage. Our results strongly suggest that uterine receptivity for implantation is expandable in pseudopregnant mice.

Animals↗
PubMed1998

Development of early porcine embryos in vitro and in vivo.

In vitro development of early porcine embryos under different culture conditions was evaluated and compared to in vivo development. First, one- and two-cell embryos were collected and cultured individually in 20- microl drops under 5% CO2 in air for 4 days. Embryos from one oviduct were cultured in NCSU-23, and those from the contralateral oviduct were cultured in KSOM/AA. The embryos developed in NCSU-23 had a higher mean number of inner cell mass (ICM) nuclei compared to those developed in KSOM/AA (p = 0.025). They also had higher trophectoderm (TE) and total nuclear number (p = 0.001), while there was no difference in the average ratio of ICM to TE nuclei (p = 0.731). When the effect of different gas atmospheres was tested, the numbers of TE and total nuclei were higher (p < 0.01 and p < 0.025, respectively) in embryos cultured in an atmosphere with 5% CO2 in air than in those developed under 5% CO2:5% O2:90% N2. Next the development of embryos cultured in NCSU-23 was compared to that of embryos incubated in vivo. By the end of the 4-day incubation, the cultured embryos had higher nuclear numbers and a higher ratio of ICM to TE nuclei than those developed in vivo (p < 0.001). Finally, the embryos that developed in NCSU-23 or in vivo were transferred into recipients. By Day 40 of pregnancy, 37.1 +/- 15.3% of the in vitro- and 53.8 +/- 15.3% of the in vivo-incubated embryos formed conceptuses. These results indicate that despite the lower nuclear numbers caused by in vitro conditions, the cultured embryos were developmentally competent.

Animals↗
PubMed2006

Apoptosis-independent poor morphology of bovine embryos produced by multiple ovulation.

In multiple ovulation and embryo transfer (MOET) programmes in cattle, a considerable number of morphologically poor-quality embryos continue to be produced; this is one of the limiting factors of the technique. Apoptosis has often been implicated in developmental arrest and fragmentation; these are regarded as poor traits of embryonic quality in mammalian pre-implantation embryos. In the present study, apoptosis was assessed in morphologically poor-quality embryos in comparison with good-quality embryos that were recovered from a MOET programme. Retarded embryos (two to 16 cell stage), morulae with severe fragmentation and morphologically good-quality morulae recovered from superstimulated cows at day 7 post-insemination were subjected to TdT-mediated dUTP nick-end labelling (TUNEL) and Hoechst staining. Cell nuclei that showed both TUNEL staining and apoptotic morphology were considered to be apoptotic. Apoptotic index (AI) was calculated as the percentage of apoptotic cells per embryo. Fifteen of 17 retarded embryos and 10 of 15 morphologically poor-quality morulae did not show signs of apoptosis. The mean AIs in the morphologically poor-quality embryos (two to 16 cell stage, 2.2%; poor morulae, 1.3%) were as low as that in the good-quality embryos (2.9%). These results suggest that another mode of developmental arrest and/or fragmentation that is independent of apoptosis occurs in morphologically poor-quality embryos recovered from MOET programmes.

Animals↗
PubMed1997

Cryopreservation of equine embryos with glycerol plus sucrose and glycerol plus 1,2-propanediol.

Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were removed by successive dilutions in PBS + 15% v:v fetal calf serum (FCS) containing decreasing concentrations of the cryoprotectants. Pregnancy was diagnosed ultrasonographically in 53.3%, 13.3% and 0% of the mares in Groups 1, 2 and 3 respectively. Ultrastructural analysis showed differences between frozen/thawed and fresh embryos. In the former, embryonic cells were deformed and showed dilation of the intercellular and perivitelline spaces, a decrease of desmosome number in the junctional complexes, few microvilli on the apical surface of the trophectoderm and an almost total absence of pinocytotic vesicles. Most of the mitochondria showed regions containing dilation and irregularities on the cristae, which appeared electron-dense. The results obtained with Groups 2 and 3 embryos showed that the cryoprotectants employed were not effective in protecting the embryos against damage during freezing and thawing. Indeed, the ultrastructural changes observed in the Group 3 embryos explained the absence of any established pregnancies in this group of mares.

Animals↗
PubMed1980

Chromosomal analysis of 159 bovine embryos collected 12 to 18 days after estrus.

One hundred and fifty-nine embryos were analysed in conjunction with embryo transfer studies. Chromosome preparations were made from small biopsy fragments of trophoblast, from large portions of trophoblast and the inner cell mass, or from the entire embryo. Results obtained from fragments were similar to those obtained from large portions of trophoblast and inner cell mass. No structural chromosomal abnormalities were observed. Single triploid, diploid-triploid and diploid-hexaploid and 66 diploid-tetraploid embryos were found. The 41.5% incidence of diploid-tetraploid embryos was relatively high, and appeared to be associated with a donor factor. The transfer of 49 biopsied and analysed embryos to recipients resulted in 15 pregnancies, seven with diploid-tetraploid embryos having up to 25% of polyploid cells. The diploid-triploid and diploid-hexaploid embryos were among the transfers that did not result in pregnancy. The low incidence of embryos with chromosomal abnormalities, excluding the diploid-tetraploid embryos, may have been due to the embryos being analysed at 12 to 18 days of age rather than at an earlier age before death or degeneration could have occurred.

Animals↗
PubMed2004

Number of embryos transferred and implantation.

Multiple pregnancies are considered the most frequent and serious complication of assisted reproduction technology. To reduce the frequency of multiple pregnancies, several centers have adopted a policy of reducing the number of embryos transferred in the uterus, suggesting single embryo transfer. Even though a significant number of papers have been published on this issue, no general consensus exists on how many embryos to replace in the uterus and at which cleavage stage. We conducted a retrospective study on cycles performed throughout 2003, analyzing the relation between the number of embryos transferred and the pregnancy and implantation rates, evaluating also the role of the woman's age. No differences were found among the groups except in one-embryo transferred women, which were mostly natural cycles, for estradiol levels, number of mature oocytes retrieved, number of top quality embryos, and pregnancy rate. The implantation rate was significantly higher in the two-embryo transfers versus three-embryo transfers. We found higher pregnancy and implantation rates with similar multiple pregnancy rates in patients where only two embryos were transferred versus three embryos transfer when women were less than 35 years old. In women aged less than 35 years, which in turn have the higher expectancy of successful pregnancy and also the higher risk of multiple pregnancy, the single embryo transfer is a suitable choice for these patients.

Adult↗
PubMed2005

Influence of estrus synchronization of prepubertal gilts on embryo quality.

Synchronization and superovulation are commonly used to obtain large numbers of embryos for experimental and practical purposes. This study compared the number, quality, and in vitro development of embryos recovered from gilts following single or double estrus synchronization and superovulation. Prepubertal gilts from the single synchronization group were injected with 1500 I.U. PMSG and 1000 I.U. hCG 72 h later. The double synchronized group of gilts was treated with 750 I.U. PMSG and 500 I.U. hCG 72 h later. After 17 days, 1500 I.U. PMSG followed by 1000 I.U. hCG was administered. Five days after insemination embryos were recovered and cultured for 6 days. Both single and double hormonal stimulation schedules resulted in recovery of elevated numbers of embryos (28.4 and 23.4 vs. 11.3; p<0.01 and p<or=0.05, respectively) with a higher percentage of embryos classified as degenerated (39.2% and 43.1%, respectively) compared to the non-stimulated, control group (5.1%). The number of embryos destined for culture did not differ between the single and double synchronized groups. The highest percentage of hatched embryos was observed in the control group. In conclusion, the single synchronization and superovulation schedule is sufficient to obtain high numbers of embryos, however, both synchronization methods resulted in the recovery of considerable numbers of degenerated embryos. A higher number and percentage of hatched embryos after culture was found among embryos from the control group compared to gonadotropin-stimulated gilts.

Animals↗
PubMed2000

Clinical experience employing co-culture of human embryos with autologous human endometrial epithelial cells.

Attempts to improve the outcome in IVF and related techniques has drawn our attention to the development of culture systems that can grow embryos up to the blastocyst stage. We have developed a co-culture system with autologous human endometrial epithelial cells (EEC) that retained many features of the endometrium. In this review, we analyse our experience over the last 4 years; in particular, we address the question of whether the system would be safe and useful in cases of IVF and oocyte donation with previous implantation failure, and which factors may contribute to the failure of human embryos to develop in vitro up to the blastocyst stage. In all, 168 IVF cycles were carried out in 127 patients with 3.8+/-0.2 previous implantation failure, and 80 cycles in 57 women having oocyte donation with 3.0+/-0.2 previous implantation failure. In 168 IVF cycles, a 48.9% blastocyst formation rate was recorded; 2.3+/-0.1 blastocysts were transferred per cycle and 30 clinical pregnancies obtained (11.9% implantation and 19.6% pregnancy rates). A total of 20 IVF and 15 oocyte donation patients with three previous implantation failures in whom a day 2 embryo transfer was performed were the controls. In 88% of oocyte donation cycles, a 61.0% blastocyst formation rate was observed; 2.3+/-0.1 blastocysts were transferred per cycle and resulted in 38 clinical pregnancies (32.7% implantation and 54.3% pregnancy rates). In all, 15 cycles were cancelled (9%). In oocyte donation patients with implantation failure undergoing day 2 embryo transfer, implantation and pregnancy rates were significantly lower (4.5 and 13.3%; P < 0.01) than with co-culture; however, in IVF patients with implantation failure with day 2 transfer, results (10.7 and 35%) were similar to those with co-culture. A second question addressed was whether chromosomal abnormalities may contribute to the failure of human embryos to develop in vitro. We observed the performance of human embryos from our preimplantation diagnosis programme, which were biopsied and subsequently cultured in EEC before transfer. Out of 68 chromosomally normal embryos, 37 reached the blastocyst stage (54.4%) compared with 35 out of 104 abnormal embryos (33.6%). The present study demonstrates that co-culture of human embryos with EEC and blastocyst transfer is safe, effective, and may be a new approach to improve implantation in patients with implantation failure undergoing oocyte donation, but not in IVF patients. The system shows that abnormal embryos can also grow to the blastocyst stage, although to a lower rate. Prospective randomized studies are needed to confirm the preliminary conclusion that co-culture is an acceptable system to select good quality embryos, and the endometrium is a limiting factor in implantation that needs to be carefully managed.

Adult↗
PubMed2003

[Relationship between the human zygote type and embryo implantation potential].

OBJECTIVE: To evaluate the relationship between the human zygote types and the quality of embryos, the embryo implantation rate, the multiple pregnancy rate in IVF-ET. METHODS: By using the criteria based on the number and distribution of nucleolar precursor bodies in each pronucleus, zygotes were divided into 0-5 types according to Tesarik's methods. In order to understand the best embryo rates that came from various types of zygote, on the one hand we compared the embryo implantation rate of different kinds of zygotes, on the other hand we defined the relationship between the multiple pregnancy rate and embryo which came from 0 type or non-0 type zygotes. RESULTS: The fine embryo rate coming from 0 type zygotes wasn't different from other types. Due to using of 0 type zygote criteria, embryo implantation rate of the experimental group was high. Along with the embryo number coming from 0 type zygotes was growing, the multiple pregnancy rate was increasing. CONCLUSION: Fine embryos coming from 0 type zygotes have high implantation potency. If the transferred fine embryos came from 0 type zygotes completely, we should limit the number of transferred embryos in order to reduce the multiple pregnancy rate.

Cell Nucleus↗
PubMed2004

[Effects of leptin on development of mouse preimplantation embryos in vitro].

OBJECTIVE: To investigate the effects of leptin on development of mouse preimplantation embryos in vitro. METHODS: (1) Groups of 2-cell stage embryos randomly selected were placed in drops of CZB medium with or without recombinant leptin (10, 50, 100 and 500 ng/ml) and were cultured to the hatched blastocyst stage, and then embryo-transfer was carried out and the implantation rate was observed and determined. (2) Groups of 2-cell stage embryos randomly selected were placed in drops of leptin free CZB medium and cultured to morula stage. Then we changed the medium, randomized the embryos into CZB medium with or without recombinant leptin (10, 50, 100 and 500 ng/ml), and cultured them to the hatched blastocyst stage. RESULTS: Addition of leptin to embryo culture media promoted the development from 2-cell stage embryo to morula, blastocyst and hatched blastocyst and improved the implantation rate. Leptin at 0, 10, 50 ng/ml concentrations caused a dose-dependent promotion, nevertheless Leptin at even higher concentrations (100 and 500 ng/ml) only brought on the same promotion as what the Leptin at concentration of 50 ng/ml did (P>0.05). Addition of leptin to embryo culture media seemed to have no effects on the in vitro development from morula to blastocyst and hatched blastocyst. CONCLUSION: Leptin plays an important role in the development of preimplantation embryo. It can promote embryo development and embryo implantation.

Animals↗
PubMedDate not supplied

[Effects of growth factors FGF4, TGFalpha, and TGFbeta1 on the development of parthenogenetic embryos of C57BL/6 mice].

We studied the effects of three growth factors, fibroblast growth factor (FGF4), transforming growth factor alpha (TGFalpha), and transforming growth factor beta1 (TGFbeta1), on development of diploid parthenogenetic embryos of C57BL/6 mice, which are not capable of developing to somatic stages. Parthenogenetic embryos were treated with growth factors at optimal doses in vitro at the morula--blastocyst stages and transplanted in the uterus of pseudopregnant females. FGF4 and TGFalpha improved the development of parthenogenetic embryos at the preimplantation stages and the number of blastocysts increased under the influence of TGFalpha. All three growth factors improved the implantation of embryos in the uterus. When FGF4 or TGFbeta1 were added to the nutrient medium, 2.4 or 1.6%, respectively, of parthenogenetic embryos reached the somatic stages in utero. No somitic embryos were observed in the control. The treatment of parthenogenetic embryos with two growth factors, FGF4 and TGFbeta1, simultaneously increased the amount of somatic embryos to 7.5%, while combination of three growth factors in creased the amount of such embryos to 16.7%. In the latter case, some parthenogenetic embryos reached the stage of 25-27 pairs of somites and were 2.0-2.5 mm long. The data we obtained suggest that, when combined, the growth factors FGF4, TGFalpha, and RGFbeta1 possessed a synergistic effect leading to a significant improvement of the development of parthenogenetic C57BL/6 embryos.

Animals↗
PubMed2006

[Embryo quality evaluation according to the speed of the first cleavage after conventional IVF].

OBJECTIVE: To evaluate morphological parametres of embryos obtained in the process of conventional IVF. DESIGN: A prospective study. SETTING: Centre of Assisted Reproduction, Dept. of Obstetrics and Gynecology, Palacký University Medical School, Olomouc. METHODS: In the present study 549 embryos developing after conventional IVF in the period of 2001-2004 were evaluated. The beginning of the mitotic cleavage was assessed within the interval of 24 - 27 hours after insemination. The embryos were divided into three groups according to the speed of their division as early cleavage (EC) embryos, where two blastomeres were present at the time of assessment, break down pronuclei stage (BDPN) where the pronuclei had already disappeared, and pronuclei (PN) embryos, where both pronuclei were still present. In these groups the degree of fragmentation was evaluated on day two of cultivation and embryos were divided into four categories as: A - with regular blastomeres, without fragmentation, B - with irregular blastomeres or with fragmentation below 30%, C - with fragmentation 30-50%, D - with fragmentation above 50%. The speed of further cleavage and average number of blastomeres were evaluated on days two and three of cultivation. Statistical analysis was preformed in the Palacký University Computer Centre. The chi-square test and t test for independent samples were used. RESULTS: EC embryos were found in 45.5%, BDPN in 33.5% and PN in 21.0%. EC embryos were less fragmented (p = 0.000), had more blastomeres at the time of evaluation (p = 0.000) and their speed of cleavage was faster (p = 0.000). The cleavage of EC embryos was faster in comparisson with the PN group (p = 0.000), but there were no significant differences between the EC and BDPN groups on day two of cultivation. On day three significant difference was found also between the EC and BDPN groups (p = 0.000). CONCLUSION: The speed of the first cell cleavage is a useful additional criterion for the embryo selection for ET. EC embryos usually have better morphology and more blastomeres that the BPDN and PN ones.

Cleavage Stage, Ovum↗