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PubMed2002

Embryonic and calving losses in bovine mixed-breed twins induced by transfer of in vitro-produced embryos to bred recipients.

One or two in vitro-produced (IVP) Japanese Black (JB) cattle embryos at 8 days after in vitro fertilization were transferred to the contralateral uterine horn of previously bred Japanese Shorthorn (JSH) or JSH-JB cross recipients, and then the occurrence of early embryonic death, abortion during mid- and late gestation, and calving loss were recorded. The survival rate of embryos, including indigenous ones, was not affected by the number of embryos transferred, and a significantly higher twinning rate (68% of pregnant recipients at 80 days after transfer) was achieved when two IVP embryos were transferred, as compared with the rate when one IVP embryo was transferred (24%). In late ET (recipients at 8.5-9.0 days after the onset of oestrus), the embryo survival rate (22%) and the pregnancy rate (42%) at 80 days after ET were significantly lower than those rates in the synchronous ET (recipients at 8.0 days after the onset of oestrus; 47 and 79%, respectively). In the early ET (recipients at 6.0-7.5 days after the onset of oestrus), no significant differences from the synchronous ET were detected in these rates. Twenty-six percent of twin pregnant recipients were aborted during mid- or late-pregnancy, and 39% of twin calves were stillborn. The mean gestation length of the twin-bearing JSH dams (276 days) was 1 week shorter than that of the single-bearing JSH dams, and it was 2 weeks shorter than that of the JB dams bearing a single JB calf derived from the IVP embryos. The longer gestation length of single JB calves derived from IVP embryos resulted in a significantly higher mean birth weight than that of in vivo control calves with the standard length of gestation. In conclusion, the number of embryos to be transferred did not affect the embryo survival rate, and the transfer of two IVP embryos to previously inseminated recipients induced a significantly higher twinning rate during early pregnancy than that of one IVP embryo transfer. The incidence of embryonic losses during early pregnancy increased when Day 8 embryos were transferred to the recipients later in the oestrous cycle (>8.0 days). The results suggested that one cause of the high rate of abortions and stillbirths in twin-bearing dams is the difference in the mean gestation length between the native JSH and JB foetuses derived from transferred IVP embryos.

Abortion, Spontaneous↗
PubMed1998

Surface ectodermal wound healing in the chick embryo.

Wound healing has been studied in the surface ectoderm overlying the midbrain region of stages 16-20 chick embryos by light microscopy, scanning and transmission electron microscopy, and immunofluorescent techniques. The embryos were divided into 6 groups, i.e. stages 16-17 for groups I, V and VI, and stages 19-20 for groups II, III and IV. For groups I and II embryos, a longitudinal incision about 0.6 mm was made close to the dorsal midline and the embryos incubated for varying periods of time up to 24 h. To determine the role of actin in the process of healing, selected groups I and II embryos were stained with FITC phalloidin and the wound margins examined using a confocal microscope. Wounds of all embryos in group I and about 20% in group II healed completely within 24 h of reincubation. The process of healing involved a change in the shapes of the ectodermal cells at the wound ends. This appeared as a zipping-up of the wound from both ends. In about 80% of group II embryos where healing did not occur, wound gaping was marked. Intense actin staining (actin cable) was observed at the wound margins of groups I and II embryos suggesting that the actin purse-string mechanism may play a role during wound healing in this epithelial model. The role of tension in wound healing was also determined by placing 2 secondary wounds about 0.5-0.7 mm long close to, and at right angles to the ends of the primary wound in groups III and V embryos. The procedure decreased the tension within the ectodermal cells at the wound ends. Groups IV and VI embryos served as controls for groups III and V embryos, respectively. Healing of both primary and secondary wounds after reduction of tension was rapid. Most primary wounds in group V embryos healed completely within 3 h of reincubation and the rate of reepithelialisation after the reduction of tension was about 160% more than that in group VI (control) embryos. Similarly, most primary wounds in group III embryos were almost closed within 6 h of reincubation. Here, the rate of reepithelialisation was 80 % more than that in group IV (controls). Thus tension is an important factor in wound healing in this model.

Animals↗
PubMed2005

Vitrification of mouse embryos at various stages by open-pulled straw (OPS) method.

This study was performed to pursue the optimal condition for the cryopreservation of mouse morulae by a two-step OPS method and to investigate the feasibility of the optimal condition for vitrification of embryos at other developmental stages. First, the mouse morulae were vitrified in OPS using one-step procedure-that is, embryos were vitrified after direct exposure to EDFS30 (15% ethylene glycol (EG), 15% dimethyl sulfoxide (DMSO), Ficoll and sucrose), or two-step method-that is, embryos were first pretreated in 10%E + 10%D (10% EG and 10% DMSO in mPBS) for 30 sec, then exposed to EDFS30 for 15 to 60 sec, respectively. After vitrification and warming, the embryos were morphologically evaluated and assessed by their development to blastocysts, expanded/hatched blastocysts, or to term after transfer. The result showed that all the vitrified-warmed morulae had similar blastocyst rate compared to that of control (91.7% vs. 100%), and the highest developmental rate to expanded blastocysts (100%) or hatched blastocysts (62.3%) was observed when the morulae were pretreated with 10%E + 10%D for 0.5 min, exposed to EDFS30for 25 sec before vitrification and warming in 0.5 M sucrose for 5 min. After transfer, the survival rate (33.1%) in vivo of the vitrified morulae was higher (P > 0.05) than that of the fresh embryos (24.6%). Secondly, embryos at different stages were cryopreserved and thawed following the above program. Most (93.4 to 100%) of the embryos recovered after vitrification were morphologically normal at all the developmental stages. The blastocyst rates of the vitrified one-cell (52.5 to 66.7%) and the two-cell (63.3 to 68.9%) embryos were lower (P < 0.05) than those of the vitrified four-cell embryos (81.7 to 86.4%), the eight-cell embryos (90.0 to 93.3%), morulae (96.7 to 100%), and the expanded blastocysts rate (98.3 to 100.0%) of the vitrified early blastocysts. The highest survival rate in vivo of vitrified embryos were from the early blastocysts (40.4%), which was similar to that of fresh embryos (48.6%). The data demonstrate that the optimal protocol for the cryopreservation of morulae was suitable for the four-cell embryos to early blastocyst stages and that the early blastocyst stage is the most feasible stage for mouse embryo cryopreservation under our experimental conditions.

Animals↗
PubMed1997

Triple colour fluorescent in-situ hybridization for chromosomes X,Y and 1 on spare human embryos.

The potential for implantation of human embryos obtained by in-vitro fertilization is presumably determined to a large extent by their chromosomal constitution but cytogenetic analysis of preimplantation embryos has been hampered by a number of practical and technical problems. With the advent of fluorescent in-situ hybridization (FISH) a practical method for numerical chromosomal analysis has become available. A limited amount of data has been obtained with FISH on human embryos using probes binding to chromosomes X, Y, 16, 18 and 13/21 combined or for chromosomes X and Y or 1 and 17. It was our purpose to extend these data by the combined analysis of chromosomes X, Y and 1 in spare human embryos. A short fluorescent in-situ hybridization procedure involving the simultaneous use of three deoxyribonucleic acid probes detected with red, green, and a mixture of red and green was used to determine chromosomal abnormalities in 116 spare embryos with a poor morphological score and/or displaying one or more multinucleated blastomeres. The majority of the embryos was obtained by intracytoplasmic sperm injection. Less than half of the embryos (n = 54) were diploid and only 39 of them were uniformly XY11 or XX11; two embryos showed a non-disjunction and 13 embryos were aneuploid. Of the remainder, 22 were mosaic, nine were either haploid, triploid or tetraploid and 12 embryos were classified as chaotic. The latter pattern was particularly frequent in multinucleated blastomeres. Our data are comparable with those obtained with FISH using other chromosomal probes and confirm that the majority of preimplantation embryos carry a numerical chromosomal defect. Aneuploidy for chromosome 1 does not appear to be more common in preimplantation embryos than is reported for other chromosomes. Although the high incidence of chromosomal anomalies is presumably biased by the fact that only embryos with a poor morphological score were analysed, it nevertheless indicates that natural selection is the foremost reason for the low implantation rates of human preimplantation embryos in in-vitro fertilization (IVF) programmes.

Chromosome Aberrations↗
PubMed1998

Difficult or repeated sequential embryo transfers do not adversely affect in-vitro fertilization pregnancy rates or outcome.

In order to assist the medical team in the decision-making process and in adequate counselling of patients when encountering technical difficulties at the time of embryo transfer, we investigated the effect of difficult embryo transfer, with or without the need for cervical dilatation or repeated sequential attempts because of retained embryos in the catheter system, on in-vitro fertilization (IVF) pregnancy rates and outcome. A total of 854 consecutive embryo transfer procedures were prospectively categorized as (i) easy (smooth, unforced), (ii) difficult (requiring uterine manipulation or increased force or cervical grasping and/or accompanied by trauma), (iii) requiring cervical dilatation, or (iv) multiple (two or three) sequential attempts because of embryos retained in the catheter system. Embryo transfer was easy in 734 cases (85.9%). It was difficult in 72 (8.4%), cervical dilatation was required in 21 (2.5%), and one or two repeated attempts were needed in 27 cases (3.2%). Pregnancy rates for the different categories of embryo transfer were 23.3, 23.6, 23.8 and 29.6% respectively. There were no significant differences in the percentage of the ongoing/delivered pregnancies for the different categories of embryo transfer (69, 64.6, 60 and 62.5% respectively). There were no significant differences in the distribution of embryo transfer types among the six infertility specialists who performed the procedures. To conclude, embryo transfers that are difficult to perform or that require cervical dilatation or repeated attempts do not adversely affect pregnancy rates and outcome following IVF. Cervical dilatation, if needed for patients with cervical stenosis, should be performed at the time of the embryo transfer and not earlier. Surgical transmyometrial embryo transfer or rescheduling patients for delayed embryo transfer could be avoided in most patients. This information is important for patient management and counselling in cases of embryo transfer that are not easy to perform.

Decision Making↗
PubMed2001

One versus two embryo transfer after IVF and ICSI: a randomized study.

BACKGROUND: The main reason for adverse treatment outcome in assisted reproduction is the high rate of multiple pregnancies. The only strategy to avoid dizygotic twins is to transfer one embryo at a time. METHODS: A total of 144 women, who had had at least four good quality embryos available after IVF/intracytoplasmic sperm injection (ICSI) and who had no more than one previous failed treatment cycle, were randomized to have either one or two embryos transferred. The treatment outcomes including those after frozen embryo transfer were compared between these groups. RESULTS: The clinical pregnancy rate per transfer was 32.4% in the one embryo transfer group and 47.1% in the two embryo transfer group, the difference being not significant. Eleven twin deliveries (n = 39) occurred in the two embryo transfer group and there was one pair of monozygotic twins in the one embryo transfer group. The cumulative pregnancy rate per patient after transfer of fresh and frozen embryos was 47.3% in the one embryo transfer group and 58.6% in the two embryo transfer group. CONCLUSIONS: Our results indicate that among women who have good quality embryos in their first IVF/ICSI, good treatment results can be achieved. They support the idea of changing embryo transfer policy towards one embryo transfer without any remarkable decrease in the success rate, while dizygotic twins can be avoided.

Adult↗
PubMed2002

Pronuclear morphology scoring and chromosomal status of embryos in severe male infertility.

BACKGROUND: The study aim was to evaluate the relationship between pronuclei morphology scoring (PNMS) and the chromosomal complement of embryos in couples with severe male infertility undergoing ICSI. A total of 3116 pre-embryos was scored according to PNMS in 452 cycles. METHODS: Pre-embryos were classified into eight categories based on the alignment, size, linear or irregular distribution of pronuclear bodies (PNB), position and clarity of cytoplasmic halo and abutting of the pronucleus. These categories were subdivided into groups I and II according to the similarity and distribution of PNB. RESULTS: In total, 2574 pre-embryos formed by using ejaculated sperm, while 542 pre-embryos developed by injection of testicular sperm or round spermatids. More group II pre-embryos with markedly different morphology from group I were formed after ICSI with testicular sperm than with fresh ejaculated sperm (32.1 versus 22.7%, P < 0.01). Of 490 pre-embryos in which pronuclear morphology was evaluated, 263 were biopsied for preimplantation genetic diagnosis. The rate of chromosomal abnormality was higher in embryos developed from group II pre-embryos (52.2%) than in embryos developed from group I prezygotes (37.6%, P < 0.05). CONCLUSIONS: Group II pre-embryos had markedly different morphology from group I, and had a low rate of blastocyst formation and high risk of chromosomally abnormal embryos. When testicular sperm and round spermatids were used for ICSI, more group II pre-embryos and chromosomally abnormal embryos were produced than with ejaculated sperm. Pronuclear morphology was correlated with chromosomal complement, and impacted upon by the sperm source.

Adult↗
PubMed2002

The neglected morula/compact stage embryo transfer.

BACKGROUND: This retrospective study analysed the outcomes of 339 embryo transfers on either day 3 (n = 97) or day 4 (n = 242), and proposed a grading system for morula/compact embryos. METHODS: The morula/compact embryo grading was based on: (i) the proportion of blastomeres undergoing the compaction process; (ii) the morphology of the compacted multicellular mass; (iii) the embryo quality on day 2 and 3; and (iv) the amount of fragmentation. Embryo transfers were classified into groups as follows: group I: transferred with zero 'good' embryos; group II: one 'good' embryo; group III: two or more 'good' embryos. RESULTS: Patients on day 4 were transferred with significantly fewer embryos in groups II and III (2.58 +/- 0.9 and 2.35 +/- 0.6 respectively) when compared with the correspondent day 3 transfers (3.81 +/- 1.4 and 4.07 +/- 0.9 respectively) (P < 0.05), but had the same or higher implantation and pregnancy rates. Analysing the patients who had transfers with all 'good' embryos, day 4 transfer achieved a significantly higher implantation rate compared with day 3 transfer (46.4 versus 21.4%, P < 0.01), but the number of embryos transferred on day 4 was significantly lower than day 3 (2.1 +/- 0.5 versus 3.5 +/- 0.9, P < 0.01). CONCLUSIONS: The morula/compact embryos had great value for embryo selection, which significantly reduced the number of embryos needed for transfer.

Adult↗
PubMed2004

Embryo quality in natural versus stimulated IVF cycles.

BACKGROUND: The impact of controlled ovarian stimulation (COS) on oocyte and subsequent embryo quality remains controversial. In the present study we have compared embryo quality in natural and stimulated cycles in the same group of patients. METHODS: This retrospective study was comprised of patients with a regular menstrual cycle who had IVF after COS using rFSH in a long GnRH agonist protocol. In all stimulated cycles the patients had fresh embryos transferred and surplus good quality embryos cryopreserved. Subsequently the same patients were treated with a modified FER cycle (mFER) where thawing of the frozen embryos was combined with aspiration of the dominant follicle in the natural cycle. The embryo cleavage stage and quality score were compared between the stimulated and the natural cycle for the patients having an embryo in the natural cycle. RESULTS: In 177 cases patients returned for mFER in a natural cycle. Spontaneous ovulation had occurred in 35 cycles. In 17 cycles no oocyte was retrieved at aspiration and in 125 cycles 128 oocytes were aspirated. In the stimulated cycles from these patients we had obtained 950 embryos (cleavage rate 70.4%) versus 85 embryos (cleavage rate 66.4%) (P = 0.34) in the natural cycles. Comparing the embryos in the natural and stimulated cycles in all patients having an embryo in the natural cycle, we found no difference in the distribution between the different cleavage stages. Of the cleaved embryos, 53% in the stimulated cycles had >or=4 cells versus 59% in the natural cycles after 2 days culture (P = 0.31). In the stimulated cycles 61% of the embryos had <10% fragmentation at the time of transfer on day 2, compared to 69% in the natural cycles (P = 0.15). CONCLUSION: The administration of exogenous gonadotrophins was not reflected in cleavage capacity or quality assessment of the resulting embryos.

Adult↗
PubMed2004

Human cumulus granulosa cell gene expression: a predictor of fertilization and embryo selection in women undergoing IVF.

BACKGROUND: A biochemical marker for embryo development would increase the chance of a successful pregnancy with IVF by optimizing oocyte and embryo selection, and allow fewer embryos to be transferred. In this study, we correlated cumulus granulosa cell gene expression of hyaluronic acid synthase 2 (HAS2), cyclooxygenase 2 (COX2; PTGS2) and gremlin (GREM1) with subsequent embryo development in search of a parameter for embryo selection. METHODS: Cumulus cell gene expression was determined prospectively on eight consecutive patients undergoing IVF with ICSI. Immediately following oocyte retrieval, the cumulus was stripped from the oocyte, and cumulus gene expression for PTGS2, HAS2 and GREM1 was assessed using a one-step real-time quantitative RT-PCR assay. Oocyte quality, fertilization and embryo morphology were correlated to relative gene expression. RESULTS: Gene expression data were available on cumulus cells from 108 oocytes that developed into 70 embryos (64.8% fertilization rate). Cumulus PTGS2, HAS2 and GREM1 expression was higher from oocytes that developed into higher quality embryos (grades 3, 4 and 5) compared with lower quality embryos (grades 1 and 2) (P<0.05, P<0.001 and P<0.001, respectively). HAS2 and GREM1 expression was also higher from the cumulus surrounding oocytes that gave rise to higher grade embryos (P<0.001). The expression of PTGS2 and HAS2 was 6-fold higher, and that of GREM1 was 15-fold higher in cumulus yielding higher grade embryos versus lower grade embryos. CONCLUSION: PTGS2, HAS2 and GREM1 gene expression correlates to morphological and physiological characteristics and provides a novel approach to predict human embryo development. Ultimately, with better predictors of follicular and embryonic health, higher quality embryos can be selected and transferred, reducing higher order pregnancy rates.

Adult↗
PubMed1999

Embryo and yolk compositional relationships in broiler hatching eggs during incubation.

Developmental relationships between yolk, embryo body, and embryo liver compositions during incubation were determined in two trials. In Trial 1, embryo body moisture, fat, and CP contents and embryo liver moisture and fat contents were determined. In Trial 2, relative yolk weights, moisture, fat, and fatty acid contents, relative wet and dry embryo weights and moisture contents, and relative wet and dry liver weights and moisture contents were determined. In Trial 1, embryo moisture decreased sigmoidally between Days 6 and 21, whereas embryo fat increased between Days 12 and 21 of incubation; embryo CP displayed sequential fluctuations throughout incubation. However, an overall significant decrease in embryo CP occurred between Days 6 and 21. Liver fat content increased between Days 12 and 21, whereas liver moisture decreased through Day 18, with a subsequent increase by Day 21. In Trial 2, relative yolk weight and moisture content decreased, whereas percentage yolk lipid content increased between Days 6 and 15. Relative wet and dry embryo weights changed in a similar manner, with rapid increases between Days 12 and 18 of incubation. Embryo moisture and CP were negatively correlated to embryo fat content. Furthermore, relative embryo and liver DM were related to yolk palmitic acid concentration, whereas yolk oleic acid was correlated only with liver DM. In conclusion, embryos and their livers displayed differential accumulations of moisture and DM during incubation, and these differences exhibited distinctive associations with various yolk fatty acids.

Animals↗
PubMed1986

Effect of asynchronous superinduction on embryo survival and range of blastocyst development in swine.

The importance of uniform development of blastocysts was examined by comparing the effects of asynchronous superinduction (Day 6 embryos into Day 7 pregnant recipients and Day 7 embryos into Day 6 pregnant recipients) on the range of embryo development at Days 12 and 13 to subsequent survival to Day 30. Twenty gilts were used to produce five Day 7 recipients that received Day 6 embryos and five Day 6 recipients that received Day 7 embryos. Embryos from the Day 7 and Day 6 recipients were examined 6 days later. Recovered embryos ranged morphologically from spherical to filamentous blastocysts. This range of embryos was within the limits of that previously observed for naturally mated sows. However, recovered blastocysts from the Day 6 embryos transferred into Day 7 recipients were morphologically more variable and proportionately less developed than the blastocysts from the Day 7 embryos transferred into Day 6 recipients. Forty additional gilts were subsequently utilized to generate 20 recipients (10 recipients per transfer group) that were examined on Day 30. More Day 7 embryos transferred into Day 6 recipients survived (p less than 0.05) than Day 6 embryos transferred into Day 7 recipients. These experiments suggested that greater variation in early development of embryos, within litters, subsequently resulted in greater mortality of embryos.

Animals↗
PubMed1997

Adenovirus-mediated gene transfer by perivitelline microinjection of mouse, rat, and cow embryos.

To determine the fate of an episomally expressed transgene, mouse, rat, and cow zygotes were injected into the perivitelline space with approximately 100 pl of buffer containing the replication-defective human adenovirus, AdCMVLacZ/sub360. Viral concentrations ranged from 2.5 to 2.5 x 10(5) plaque-forming units (pfu)/100 pl. As viral titer increased, fewer embryos were able to develop to blastocysts. In the mouse, the percentage of blastocysts formed ranged from 82% in controls to 16% after injection at the highest titer. In the rat and cow, a similar decrease in blastocyst formation was noted (62% to 6% and 26% to 4%, respectively). Reporter gene (galactosidase, LacZ) activity could be detected in mouse embryos after injection at a concentration of only 25 pfu/100 pl, whereas a tenfold higher titer was required in the other two species to observe the blue LacZ reaction product. When examined after 5 (mouse), 6 (rat), or 9 (cow) days of in vitro culture, the proportion of LacZ-positive embryos ranged from 15% to 96%, 6% to 76%, and 18% to 58% in mouse, rat, and cow embryos, respectively, depending upon viral concentration. However, a large percentage of positive embryos proved to be expression mosaics, the degree of which was likewise dependent on titer. While none of the embryos showed LacZ activity at 30 h after injection, 70% of mouse, 8% of rat, and 20% of cow embryos expressed the reporter gene at 42 h. Delaying the timing of injection revealed that the efficiency with which mouse and rat embryos could be infected decreased with increasing degree of differentiation. Only 35% and 18% of mouse embryos expressed the reporter gene after injection at the morula or blastocyst stage, respectively. A similar drop in efficiency was noted in rat embryos when injections took place at the 8-cell, morula, or blastocyst stage, with 70%, 33%, and 9% of embryos, respectively, subsequently showing LacZ activity. Likewise, advanced development resulted in a decrease in the efficiency of viral-mediated gene transfer in cow embryos, with 100%, 78%, and 68% of embryos being positive after injection at the 8-cell, morula, or blastocyst stage, respectively. These results demonstrate that a human adenovirus can be used to express a reporter gene transiently in nonhuman embryos.

Adenoviridae↗
PubMed2005

Relation between physical properties of the zona pellucida and viability of bovine embryos after slow-freezing and vitrification.

In vitro-produced bovine morulae/blastocyst embryos (n = 119) were slow-frozen and vitrified and the physical alterations of the zona pellucida (ZP) was observed by scanning electron microscopy (SEM) to find an explanation for the loss of developmental capacity of the embryos after freezing/thawing. A control group was provided, in which embryos (n = 38) were neither frozen nor vitrified. Embryos were in vitro-cultured in a standard CO2 Heraeus incubator and their viability was assessed 24 and 48 h after the start of culture, evaluating their morphological aspect. After 24 h of culture, embryo survival rate for slow-freezing/thawed (n = 23), vitrified/thawed (n = 20) and control embryos (n = 20) was 39, 27 and 90%, and 35, 14 and 65% after 48 h of culture, respectively. For evaluation of physical changes occurring in ZP, 20 embryos were slow-frozen, 18 were vitrified and 18 were used as control. All embryos were fixed, dried and examined under an SEM. Embryo's diameter, as well as the number of pores and their diameter was measured in squares of 6.4 microm width. We observed that, on average, the diameter of the embryos (92.26 +/- 10.15 microm) did not differ significantly among all embryos. As far as the diameter of the pores in the outer surface of the ZP is concerned, the results revealed a significant difference (P < 0.05) between control (0.48 +/- 0.0025 microm), slow-frozen (0.34 +/- 0.0007 microm) and vitrified (0.27 +/- 0.0006 microm) embryos. For the number of pores, statistical differences (p < 0.05) were observed between control and vitrified embryos (45.4 +/- 7.3 vs 38.2 +/- 8.2). It is possible that ZP functions as a barrier which is positive when dealing with pathogens, but is harmful when nutrients were supplied from the outside, especially at 48 h of culture. Results indicate that the steps of cryopreservation cause alterations in ZP, with irreversible damage on the further developmental competence of bovine embryos.

Animals↗
PubMed2007

Cellular composition and viability of cloned bovine embryos using exogene-transfected somatic cells.

The present study compared the efficiency of transgenic (TG) cloned embryo production by somatic cell nuclear transfer (SCNT) with fetal-derived fibroblast cells (FFCs) which were transfected with pEGFP-N1 to in vitro-fertilized (IVF), parthenogenetic and SCNT counterparts by evaluating the rates of cleavage and blastocyst formation, apoptosis rate at different developmental stages, cell number, ploidy and gene expression in blastocysts. In SCNT and TG embryos, the rates of cleavage and blastocyst formation were significantly lower (p < 0.05) than those of IVF controls, but it did not differ between SCNT and TG embryos. In IVF control, 86.7% embryos displayed diploid chromosomal complements and the rates were significantly (p < 0.05) higher than those of SCNT and TG embryos. Most TG embryos (79%) with FFCs expressed the gene by both PCR and under fluorescence microscopy. The expression of apoptosis by TUNEL was first detected at six to eight cell stages in all embryos of IVF, SCNT and TG groups, but the expression rate at each developmental stages was significantly higher (p < 0.05) in SCNT and TG embryos than in IVF counterparts. The expression rate in inner cell mass (ICM) of TG embryos was significantly higher (p < 0.05) than in SCNT and IVF embryos. These results indicate that the high occurrence of apoptosis observed in SCNT and TG embryos compared with IVF counterparts might influence the developmental competence. Moreover, the SCNT embryos derived using non-transfected donor cells exhibited a lower apoptosis expression in ICM cells than in TG embryos derived using pEGP-N1-transfected donor cells suggesting a possible role of negative gene effect in TG embryos.

Animals↗
PubMed1997

The risks of disease transmission by embryo transfer in cattle.

Guidelines for the safe international movement of livestock embryos are provided in the International Animal Health Code of the Office International des Epizooties, and recommendations for embryo processing, based on numerous research papers on embryo-pathogen interaction studies, are given in the Manual of the International Embryo Transfer Society. Risk assessment is the logical extension of these approaches, since it provides veterinary authorities with a complete package of information on which to base their import/export decisions. Risk assessment includes evaluation of disease prevalence, effectiveness of Veterinary Services and competence of the embryo collection team. It also takes account of the epidemiology and pathogenesis of the disease concerned. The application of risk assessment for embryo movement is illustrated in this paper by comparisons of the probabilities of transmitting foot and mouth disease, bluetongue and vesicular stomatitis by bovine embryos. The risk scenario pathway was divided into three phases for analysis. The first phase deals with the potential for embryo contamination, which depends on the disease situation in the exporting region, the health status of donor herds and donor cows, and on the pathogenetic properties of the disease agent. The second phase covers risk mitigation by use of the internationally accepted standards for embryo processing, and the third phase considers the risk reductions resulting from post-collection surveillance of donors and donor herds, and also from testing of embryo-collection (flushing) fluids for the disease agent. It was evident from this assessment that low risks of transmitting disease by international movement of bovine embryos depend initially on a low disease incidence in the exporting region and on easily recognisable disease signs. Competent embryo processing was also of great importance, and in the case of bluetongue, vector ecology had a major influence. In addition to providing a logical basis for import/export decisions, risk assessment is useful for evaluating the potential outcome of new research and for assessing the safety of the movement of embryos of other species for which little or no research information is available on embryo-pathogen interactions.

Animals↗
PubMed1985

Effect of age of equine embryos and method of transfer on pregnancy rate.

A 2 X 2 cross-classified experiment was conducted to investigate the effect of age of equine embryo (7 vs 8 d postovulation) and method of transfer (surgical vs nonsurgical) on pregnancy rates at 50 d of gestation. Embryos were recovered 7 or 8 d postovulation using a Foley catheter and 3 liters of modified Dulbecco's phosphate-buffered saline (PBS). Upon identification, the embryos were placed in millipore-filtered PBS containing 20% heat-inactivated steer serum and maintained at room temperature until transferred. At the time of recovery, embryos were randomly assigned to be transferred either nonsurgically using a sterile insemination pipette or surgically via a flank incision. For nonsurgical transfer, the embryo was deposited into the uterine body; whereas, in surgical transfer, the embryo was placed in the uterine horn ipsilateral to the corpus luteum. Recovery rates for embryos collected on d 7 (75.5%) or 8 (81.9%) were similar (P greater than .05). Age of embryo did not affect (P greater than .05) pregnancy rate. At 50 d, pregnancy rates were 60 and 57% for mares receiving d 7 or 8 embryos. However, more (P less than .05) pregnancies were obtained after transfer of embryos surgically (72%) than nonsurgically (45%). More (P less than .05) pregnancies were obtained after transfer of d 8 embryos surgically (75%) compared with nonsurgically (40%). Within method of transfer, pregnancy rates were similar (P less than .05) for surgical transfer of d 7 and 8 embryos (69 and 75%), but tended (P less than .25) to be higher for nonsurgical transfer of d 7 embryos (50%) compared with d 8 embryos (40%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Intratubal transplantation of early canine embryos.

It has been reported previously that intrauterine transplantation of canine embryos is possible. In this study, the possibility of intratubal transplantation of early canine embryos was investigated. Beagles at ovulation +/- 1 day estimated from peripheral blood progesterone concentrations were used as embryo donors and recipients. The Beagles (n = 13) were mated 1-4 days after ovulation and embryos were collected 1-3 days after mating (3-7 days after ovulation) by tubal flushing or salpingectomy. Embryos were transplanted using a glass tube or catheter into the upper or lower uterine tubes at 1.5 and 5.0 cm from the fimbriae tubae, respectively. The mean embryo yield from three bitches from which embryos were collected by tubal flushing was 28.2%. Embryos collected from ten bitches by salpingectomy were at the syngamy to eight-cell stages of development, and the mean yield was 95%. Embryos (1-7 per bitch) were transplanted into the upper uterine tube of seven recipient bitches and to the lower uterine tube of eight recipient bitches. It was found that no bitches in which embryos were transplanted into the upper uterine tubes became pregnant, whereas four bitches (50%) in which embryos were transplanted into the lower uterine tubes became pregnant (P < 0.05, chi-squared test). The success of embryo transfer was not affected by differences in embryo stage or day of ovulation. In conclusion, it is possible to impregnate bitches by transplanting early canine embryos into the lower uterine tubes.

Animals↗