References of "Ectors, Fabien"
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See detailThe ovarian follicle in cow: in vivo growth and in vitro culture
Beckers, Jean-François ULg; Drion, Pierre ULg; Figueiredo, J. R. et al

in Reproduction in Domestic Animals (1996), 31

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See detailTrophoblastic disregulations in pregnancies resulting from transfer of cloned embryos in the bovine species
Ectors, Fabien ULg; Delval, A.; Smith, Lawrence et al

in 12e Colloque Scientifique de l'Association Européenne du Transfert Embryonnaire (1996)

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See detailLe clonage par transfert de noyau dans l'espece bovine: resultats et perspectives.
Ectors, Fabien ULg

in Bulletin et Mémoires de l'Académie Royale de Médecine de Belgique (1996), 151(12), 493-9

A all in vitro cloning technique was developed in which the reconstituted embryos from the first cycle nuclear transfer (cloning) were used as blastomere donor for the second cycle nuclear transfer ... [more ▼]

A all in vitro cloning technique was developed in which the reconstituted embryos from the first cycle nuclear transfer (cloning) were used as blastomere donor for the second cycle nuclear transfer (recloning). Such method permitted to produce 14.5% of morulae and 14.9% of blastocysts after the first and second cycles of nuclear transfer, respectively. The rates of birth obtained after transfer of such embryos were 21.4% et 20.8% for first and second cycles respectively, corresponding to 6 et 5 calves for 28 et 24 transferred embryos. Unfortunately, gestation pathologies and an increase of birth weights were observed. It seems that the in vitro presence of gametes and/or embryos may be responsible of an alteration in the control of gene expression. [less ▲]

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See detailAssessment of nuclear totipotency of fetal bovine diploid germ cells by nuclear transfer.
Moens, A.; Chesne, P.; Delhaise, F. et al

in Theriogenology (1996), 46(5), 871-80

Nuclear transfer was used to study nuclear reprogramming of fetal diploid bovine germ cells collected at two stages of the fetal development. In the first case, germ cells of both sexes were collected ... [more ▼]

Nuclear transfer was used to study nuclear reprogramming of fetal diploid bovine germ cells collected at two stages of the fetal development. In the first case, germ cells of both sexes were collected during their period of intragonadal mitotic multiplication at 48 days post coitum (d.p.c.). In the second case, only male germ cells were collected after this period, between 105 and 185 d.p.c. Isolated germ cells were fused with enucleated oocytes. Reconstituted embryos were cultured in vitro and those reaching the compacted morula or blastocyst stage were transferred into synchronous recipient heifers. Of 511 reconstituted embryos with 48 d.p.c. germ cells (309 males and 202 females), 48% (247/511 ) cleaved; 2.7% (14/511 ) reached the compacted morula stage and 8 of them the blastocyst stage (1.6%). No difference was observed between sexes. All 14 compacted morulae/blastocysts were transferred into 6 recipients and one pregnancy was initiated. This recipient was slaughtered at Day 35 and an abnormal conceptus (extended trophectoderm and degenerated embryo) was collected. Its male sex, genetically determined, corresponded to that of donor fetus. Of 380 reconstituted embryos with male 105 to 185 d.p.c. germ cells, 72.1% (274/380 ) cleaved, 2.1% (8 380 ) reached the compact morula stage and 7 of these the blastocyst stage (1.8%). Three blastocysts and one morula were transferred into 4 recipients. Two became pregnant at Day 21 but only one at Day 35 which aborted around Day 40. Our results show that the nucleus of diploid bovine germ cells of both sexes can be reprogrammed. However, in the absence of further development of these reconstituted embryos, nuclear totipotency of bovine diploid germ cells remains to be evidenced. [less ▲]

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See detailCytogenetic study of bovine oocytes matured in vitro
Ectors, Fabien ULg; Koulischer, Lucien ULg; Jamar, M. et al

in Theriogenology (1995), 44(3), 445-450

Described in the present paper is a cytogenetic study of bovine oocytes matured in vitro. The cumulus-oocyte complexes (COC), punctured from ovaries recovered in a local slaughterhouse, were classified ... [more ▼]

Described in the present paper is a cytogenetic study of bovine oocytes matured in vitro. The cumulus-oocyte complexes (COC), punctured from ovaries recovered in a local slaughterhouse, were classified into 3 groups according to follicular diameter 1 to 4mm, 5 to 8mm and 9 to 13 mm. Metaphases available for observation were classified as metaphase I, haploid and diploid metaphase II. High levels of haploid metaphases II (90.6, 86.9 and 94.4 %) among the 3 groups of follicular sizes indicated successful meiotic resumption during in vitro maturation and suggested that cytoplasmic maturation may be responsible for low developmental rate after IVM, IVF and in vitro development (IVD). [less ▲]

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See detailFractionation and partial characterization of proteins extracted from the bovine fallopian tube: preparation of tools for further purifications
Remy, Benoît ULg; Rabahi, F.; Duwez, L. et al

in Theriogenology (1995), 44(1), 95-107

Described in the present paper is a combined biochemical and immunological approach to study oviductal proteins in the bovine. Antisera were raised against semi-purified proteins extracted from bovine ... [more ▼]

Described in the present paper is a combined biochemical and immunological approach to study oviductal proteins in the bovine. Antisera were raised against semi-purified proteins extracted from bovine tubal mucosal tissue and were characterized. These antisera are available to monitor puritications of specific oviductal proteins in the future. Oviducts from 170 cyclic cows were collected at a slaughterhouse, and high amounts of mucosal proteins were extracted. The proteins were fractionated after precipitation with ammonium sulfate, anti-bovine serum albumin (bSA) and anti-bovine immunoglobulins bIg) afiinity chromatography and ion exchange chromatography. Each of the 12 fractions obtained after ion exchange chromatography was used to immunize a rabbit. Conditioned media were recovered from bovine oviduct cell monolayers cultured without serum to cot&m the oviductal origin of the extracted proteins. After Western blot analysis, 15 proteins were detected in the bovine oviductal extracts, and their molecular weights and isoelectric points were determined by 2 dimensional electrophoresis. Among these 15 proteins, 11 were also detected in conditioned media of bovine oviductal cells. These results demonstrate an oviductal origin of the 11 detected proteins and strongly suggest their secretion by the oviductal cells. [less ▲]

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See detailLe clonage par transfert de noyaux dans l'espèce bovine
Ectors, Fabien ULg

Doctoral thesis (1995)

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See detailNuclear transplantation using bovine primordial germ cells from male fetuses.
Delhaise, F.; Ectors, Fabien ULg; de Roover, R. et al

in Reproduction, Fertility and Development (1995), 7(5), 1217-9

The developmental potential of nuclei of bovine gonial cells was investigated by nuclear transfer. Gonial cells were collected from male fetuses at about 175 days post coitum (p.c.). They were fused with ... [more ▼]

The developmental potential of nuclei of bovine gonial cells was investigated by nuclear transfer. Gonial cells were collected from male fetuses at about 175 days post coitum (p.c.). They were fused with enucleated oocytes; reconstituted embryos were cultured in vitro for 7 days. Embryos reaching the compacted morula or blastocyst stage were either fixed for cell counting or transferred into recipients. Out of 115 oocyte-gonia fusions, 101 (87.8%) gave rise to cleaved embryos at Day 3 and 26 (22.6%) had reached the 8-cell stage. At Day 7, 1 (1%) developed to the morula stage and 5 (4%) reached the blastocyst stage. Three blastocysts were fixed and showed normal cell numbers (135; 90; 76 cells). Three blastocysts and one morula were transferred in four recipients; two recipients were pregnant at Day 21 but only one was positive at Day 35 p.c.; this last one aborted around Day 40 p.c. No conceptus was collected. These results indicate that gonial cell nuclei can be partially reprogrammed; they are able to develop into blastocysts and to initiate gestation. However, more experiments will be necessary to prove the nuclear totipotency of bovine gonial cells. [less ▲]

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See detailViability of cloned bovine embryos after one or two cycles of nuclear transfer and in vitro culture
Ectors, Fabien ULg; Delval, Alain; Smith, Lawrence et al

in Theriogenology (1995), 44

We described an exclusively in vitro procedure for cloning and recloning bovine embryos. Embryos obtained by IVM/IVF/IVC developed to the morula stage were used as blastomere donors in cunjunction with ... [more ▼]

We described an exclusively in vitro procedure for cloning and recloning bovine embryos. Embryos obtained by IVM/IVF/IVC developed to the morula stage were used as blastomere donors in cunjunction with IVM recipient oocytes. Reconstructed embryos were developed in vitro in co-culture using bovine oviductal epithelial cells. The resulting morulae were used as donors for recloning under the same experimental conditions. No significant difference was observed between cloning and recloning in terms of development (rates of blastocysts: 12.9 versus 14.9%), in the number of nuclei per blastocyst (63.8 versus 49.1), or in pregnancy rates (35.7 versus 33.3%). The high variability observed between replicates and the correlation between results in first and second cycle nuclear transfer may suggest an inherant potential of individual donor embryos to support development by cloning [less ▲]

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See detailLe determinisme genetique de la differenciation sexuelle humaine.
Ectors, Fabien ULg

in Revue Médicale de Bruxelles (1995), 16(6), 404-10

The genetic mechanism controlling sexual differentiation had remained unknown for a long time. Karyotype analysis of sex-inverted patients or individuals with ambiguous sexual differentiation has enabled ... [more ▼]

The genetic mechanism controlling sexual differentiation had remained unknown for a long time. Karyotype analysis of sex-inverted patients or individuals with ambiguous sexual differentiation has enabled the localization and identification of genes involved. It is currently known that the SRY gene is responsible for the initiation of a cascade reaction leading to male differentiation of the primitive gonad. SRY is a +/- 820 base pairs gene located on the small arm of the Y chromosome, more precisely within the 1A1 alpha sub-segment. Although a few other genes are known to be involved in the downstream regulation of SRY, their precise mode of action is yet unknown. [less ▲]

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See detailLe point sur la production d’embryons in vitro: limitations et perspectives de la recherche
Thonon, Fabienne; Ectors, Fabien ULg; Delval, Alain et al

in Annales de Médecine Vétérinaire (1994), 138(1), 33-40

Recent progress in gamete biology and early embryo development was responsible for great evolution of reproduction techniques in farm animals. Among these techniques, in vitro production of bovine embryos ... [more ▼]

Recent progress in gamete biology and early embryo development was responsible for great evolution of reproduction techniques in farm animals. Among these techniques, in vitro production of bovine embryos was developed from slaughterhouse ovaries. This method has been used for individual animals. However, large variations in results were observed, due to several factors, including reproductive state and age of the donor. Inspite of this limitation, in vitro production of bovine embryos may be helpful, when slaughtering of valuable cows is recommended eg for brucellosis disease. Researches are purchased in order to increase the number of oocytes obtained per "elite" cow and to improve the ability of in vitro embryos to support freezing. [less ▲]

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See detailPreservation of Oocyte and Granulosa Cell Morphology in Bovine Preantral Follicles Cultured in Vitro
Figueiredo, J. R.; Hulshof, S. C.; Van den Hurk, R. et al

in Theriogenology (1994), 41(6), 1333-46

Described in the present paper is a culture system that preserves oocyte and granulosa cell morphology in bovine preantral follicles during 5 d in vitro. The effects of additional hypoxanthine and energy ... [more ▼]

Described in the present paper is a culture system that preserves oocyte and granulosa cell morphology in bovine preantral follicles during 5 d in vitro. The effects of additional hypoxanthine and energy substrata (i.e., pyruvate and glutamine) on the morphology of cultured preantral follicles were investigated. It was shown that addition of a mixture of pyruvate, glutamine and hypoxantine to the culture medium increased the percentage of follicles with an intact oocyte from 29.4 to 78.6%. Morphological criteria are described to discriminate between normal and degenerated preantral follicles during culture by inverted microscopy. In addition, the importance of histological evaluation to judge the quality of oocyte and granulosa cells is demonstrated. [less ▲]

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See detailClonage par greffe de blastomère: naissance d'un premier veau
Ectors, Fabien ULg; Delval, Alain; Touati, Kamal ULg et al

in Annales de Médecine Vétérinaire (1993), 137(8), 573-574

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See detailDevelopment of a combined mechanical and enzymatic method for the isolation of intact preantral follicles from fetal, calf and adult bovine ovaries
Figueiredo, José Ricardo; Hulshof, S. C. J.; Van den Hurk, R. et al

in Theriogenology (1993), 40(4), 789-799

The isolation of preantral follicles from the ovaries of bovine fetuses, calves and adult cows was performed using a simple, rapid mechanical and enzyme method. The ovaries were cut into small pieces with ... [more ▼]

The isolation of preantral follicles from the ovaries of bovine fetuses, calves and adult cows was performed using a simple, rapid mechanical and enzyme method. The ovaries were cut into small pieces with a tissue chopper. Then, the suspension was filtered successively through 500 and 100 μm nylon mesh filters. This simple mechanical procedure resulted in large numbers of isolated preantral follicles: 2,142 ± 254; 512 ± 92 and 298 ± 54 from the ovaries of bovine fetuses, calves and cows, respectively. In addition, the ovarian fragments between 100 and 500 μm were suspended in 10 ml of M199 Hepes medium plus 5% FCS and divided into 2 equal parts: one portion was used for collagenase treatment (200 U/ml) for 20 minutes, while the other served as a control. Collagenase treatment resulted in 841 ± 161; 216 ± 51 and 52 ± 17 preantral follicles from fetuses, calves and cows, respectively, compared with 312 ± 86; 52 ± 15 and 10 ± 2 in the control group. The use of collagenase with ovarian fragments selected by filtration as a method for increasing the rate of recovery of preantral follicles is described here. [less ▲]

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See detailLe clonage par transfert de noyau dans l'espèce bovine: premiers résultats
Ectors, Francis ULg; Ectors, Fabien ULg; Delval, Alain et al

in Bulletin et Mémoires de l'Académie Royale de Médecine de Belgique (1993), 148

In 1987, Prather et al. have performed the first embryo cloning by nuclear transfer in the bovine species. Since, many researchers try to develop and to apply the technique. While the enucleation of the ... [more ▼]

In 1987, Prather et al. have performed the first embryo cloning by nuclear transfer in the bovine species. Since, many researchers try to develop and to apply the technique. While the enucleation of the recipient oocyte, the injection of the donor blastomere and the fusion procedure are now well controlled, on the other hand, maturation and activation as the development and freezing of the cloned embryos need tobe more investigated. The cloned embryo is more fragile. An increase in embryonic mortality is observed after transfer in a recipient cow. [less ▲]

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See detailClonage par transfert de noyau dans l'espèce bovine: premiers résultats
Ectors, Fabien ULg; Delval, Alain; Touati, Kamal ULg et al

in Annales de Médecine Vétérinaire (1993), 137(6), 427-431

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See detailComparison between culture of bovine embryos in vitro versus development in rabbit oviducts and in vivo
Ectors, Fabien ULg; Thonon, Fabienne; Delval, Alain et al

in Livestock Production Science (1993), 36

The aim of this work was to evaluate the efficiency of different embryo culture methods for in vitro embryo production: development in co-culture with bovine oviductal epithelial cells (BOEC), in BOEC ... [more ▼]

The aim of this work was to evaluate the efficiency of different embryo culture methods for in vitro embryo production: development in co-culture with bovine oviductal epithelial cells (BOEC), in BOEC conditioned medium (CM) or in rabbit oviducts, versus in vivo produced embryos. There was no significant difference in terms of percentages of cleaved and 8-cell stages obtained between CM and BOEC. In CM, 24.8% of the cleaved embryos became blastocysts. In BOEC, 14.5% of the cleaved embryos became blastocysts. Among the 190 zygotes transferred in the rabbit oviducts, 127 have been recovered 5 days later, and 17.4% became blastocysts. There was no significant difference in term of blastocyst formation between the development in rabbit and in BOEC. However, there was a significant difference between the CM group and the two other groups. The numbers of cells in blastocysts from different sources were investigated: in vivo blastocysts contained 107 cells assumed to be 100%, in vitro blastocysts developed in rabbit oviduct 100.1 cells (93.3%), BOEC blastocysts 90.8 cells (84.6%) and CM blastocysts 72.3 cells (67.3%). This study confirmed earlier works on the oviduct effect on blastocyst quality in terms of development rate and cell number. [less ▲]

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See detailLe sexage d'embryons bovins par la technique de l'amplification en chaîne par la polymérase (acp) d'une séquence Y-spécifique bovine
Grobet, Luc ULg; Schwers, Anne; Charlier, Carole ULg et al

in Annales de Médecine Vétérinaire (1992), 136

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See detailMultiplication des embryons chez les bovins: possibilités actuelles et futures
Ectors, Francis ULg; Beckers, Jean-François ULg; Ectors, Fabien ULg et al

in Biotechnologie en Sélection animale - IRSIA (1989)

Since several years, research efforts have been focused towards improving the reproductive potential of domestic animals. The authors present a review of different technics in particular the ... [more ▼]

Since several years, research efforts have been focused towards improving the reproductive potential of domestic animals. The authors present a review of different technics in particular the superovulation and priming, embryo micromanipulation and clonage. The technic of superovulation allows an increase of the total number fo the offspring by an increase of the ovocytes total number. Different FSH injections at the end of the cycle, preceded by small FSH quantity at the beginning of the cycle, procure a great number of mature follicles available for reproduction. Micromanipulation allows a multiplicaton by sectioning the embryo in two or more segments. Isolated blastmeres can also be used but it was observed that those cells very rapidly loose their differentiation potential. Clonage allows the reproduction of an animal from only one of his own cells. The nucleus of this cell is extracted and reimplanted in an enucleated ovocyte. Meanwhile from a practical point of vue, this technic is, at present, only possible using a stem cell and not using a mature somatic cell. [less ▲]

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