References of "Ectors, Fabien"
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See detailAseptic vitrification of blastocysts from infertile patients, egg donors and after IVM
Vanderzwalmen, Pierre ULg; Ectors, Fabien ULg; Grobet, Luc ULg et al

in Reproductive Biomedicine Online (2009), 19(5), 700-707

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See detailL'animalerie Souris SPF du GIGA
Ectors, Fabien ULg; Bay, Daniel ULg

Diverse speeche and writing (2007)

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See detailExpression of Hoxa2 in cells entering chondrogenesis impairs overall cartilage development.
Massip, Laurent; Ectors, Fabien ULg; Deprez, Pierre et al

in Differentiation : Research in Biological Diversity (2007), 75(3), 256-67

Vertebrate Hox genes act as developmental architects by patterning embryonic structures like axial skeletal elements, limbs, brainstem territories, or neural crest derivatives. While active during the ... [more ▼]

Vertebrate Hox genes act as developmental architects by patterning embryonic structures like axial skeletal elements, limbs, brainstem territories, or neural crest derivatives. While active during the patterning steps of development, these genes turn out to be down-regulated in specific differentiation programs like that leading to chondrogenesis. To investigate why chondrocyte differentiation is correlated to the silencing of a Hox gene, we generated transgenic mice allowing Cre-mediated conditional misexpression of Hoxa2 and induced this gene in Collagen 2 alpha 1-expressing cells committed to enter chondrogenesis. Persistent Hoxa2 expression in chondrogenic cells resulted in overall chondrodysplasia with delayed cartilage hypertrophy, mineralization, and ossification but without proliferation defects. The absence of skeletal patterning anomaly and the regular migration of precursor cells indicated that the condensation step of chondrogenesis was normal. In contrast, closer examination at the differentiation step showed severely impaired chondrocyte differentiation. In addition, this inhibition affected structures independently of their embryonic origin. In conclusion, for the first time here, by a cell-type specific misexpression, we precisely uncoupled the patterning function of Hoxa2 from its involvement in regulating differentiation programs per se and demonstrate that Hoxa2 displays an anti-chondrogenic activity that is distinct from its patterning function. [less ▲]

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See detailCryopreservation des embryons humains par vitrification.
Vanderzwalmen, Pierre ULg; Zech, Nicolas; Greindl, A.-J. et al

in Gynécologie Obstétrique & Fertilité (2006), 34(9), 760-9

Vitrification is a cryopreservation strategy where cells are converted into a glass-like amorphous solid which is free of any crystalline structure. Such process is achieved by a combination of high ... [more ▼]

Vitrification is a cryopreservation strategy where cells are converted into a glass-like amorphous solid which is free of any crystalline structure. Such process is achieved by a combination of high concentration of cryoprotectant and an extremely high cooling rate. In the last years, survival rates of up to 80% after thawing and pregnancy rates of almost 30% could be achieved after transfer of vitrified embryos at the zygote, cleavage, morula and blastocyst stages. Also deliveries of healthy babies have been reported numerous times. To this day, a limited interest in this technique can be noted. The explanation may lye in the apprehension of many ART units regarding exposure of embryos to high concentrations of cryoprotectants and storage in non sterile conditions. The aim of the first part of this article, is to analyse if such fears are justified on the basis that vitrification mimics conditions already in use for many years in slow-cooling procedures where cells are plunged into liquid nitrogen at around -30 degrees C and secondly since storage of embryos are now possible in high aseptic conditions. In the second part, results on survival after thawing, pregnancy rates and baby take home rates of vitrified embryos will be presented and the problems associated with vitrification of blastocysts will be discussed. [less ▲]

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See detailFrom the germinal cells to the newborn animal: The transmission of genes and life through the generations
Drion, Pierre ULg; Szenci, Otto; Ectors, Fabien ULg et al

in Acta Veterinaria Hungarica (2003), 51(3), 371-384

The technology of reproduction progressed considerably during the last decade, leading to a certain availability of in vitro methods for fertilisation, oocyte maturation and embryo culture. The most ... [more ▼]

The technology of reproduction progressed considerably during the last decade, leading to a certain availability of in vitro methods for fertilisation, oocyte maturation and embryo culture. The most spectacular manipulations are cloning and transgenesis. This review focuses on the early appearance of germinal cell precursors and the long-standing fate of gametes in mammals. The evident complexity and long-term programming of events in gametes and early embryos explain part of the difficulties encountered during the development of in vitro and in vivo methods such as multiple Ovulation and embryo transfer (MOET), oestrus synchronisation, ovulation induction, superovulation, in vitro maturation and fertilisation, cryopreservation, transgenesis, nuclear transfer and cloning) and the occurrence of unexpected alterations of development, e.g. embryonic or fetal mortality, large-weight newborn syndrome and other dysregulations ill imprinting or DNA transmission. [less ▲]

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See detailEmbryo transfer as a method to eliminate pathogenic agents in a rabbit colony
Ectors, Fabien ULg; Delfosse, Henri; De Weder, L. et al

in Vlaams Diergeneeskundig Tijdschrift (2002), 71

To regain the SPF status of a contaminated but genetically valuable rabbit breeding unit, embryos from the contaminated does were transferred into SPF recipient females. Embryos were collected on day 3 of ... [more ▼]

To regain the SPF status of a contaminated but genetically valuable rabbit breeding unit, embryos from the contaminated does were transferred into SPF recipient females. Embryos were collected on day 3 of gestation by flushing uterine horns. All usable embryos were frozen, part of them were not transferred and kept in liquid nitrogen forming a stock of highly valuable genotypes. Thirty-two stimulated does produced 893 embryos, among which 821 (92%) had an intact zona pellucida and were cryopreserved. From this stock, 478 embryos were thawed, 466 were recovered (97.5%) and 417 were of good quality (87.2%). In 30 does, 10 to 18 embryos were surgically transferred per recipient doe and 24.9% (104/417) of them developed to term after transfer. This corresponds to an average number of 3.47 (104/30) live newborns per recipient. Health screenings performed on sanitized rabbits confirmed the disappearance of pathogenic agents. [less ▲]

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See detailLa méiose chez la femelle de mammifère
Ectors, Fabien ULg; Koulischer, Lucien

in Popescu, Paul; Hayes, Hélène; Dutrillaux, Bernard (Eds.) Techniques de cytogénétique animale (1998)

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See detailBovine pregnancy-associated glycoprotein profiles as indicators of trophoblastic function after in vitro manipulation or culture
Ectors, Fabien ULg; Sulon, José; Delval, A. et al

in Reproduction in Domestic Animals (1997, February), 32(1-2), 52

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See detailRegolazione della crescité follicolare e luteinica. Folliculogenesi e atresia. Summa.
Drion, Pierre ULg; Beckers, Jean-François ULg; Ectors, Fabien ULg et al

in Summa (1997), 14(9), 5-16

Hypophyseal production of FSH and LH depends on a pulsating secretion of GnRH by the Hypothalamus. At the beginning of the cycle, this secretion sets free the FSH from the hypothesis responsible for ... [more ▼]

Hypophyseal production of FSH and LH depends on a pulsating secretion of GnRH by the Hypothalamus. At the beginning of the cycle, this secretion sets free the FSH from the hypothesis responsible for follicular recruiment. The recruited follicles produce estradiol, inhibin and follistatin which reduce the FSH secretion (negative feed back) reducing their support to hormonodependant follicles which become atresic. The dominant follicle, subjected to internal self stimulation is not sensitive to the reduction in FSH levels and carries on synthesising more and more estradiol. [less ▲]

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See detailLe clonage par transfert de noyau dans l'espèce bovine
Ectors, Fabien ULg; Delval, Alain; Beckers, Jean-François ULg et al

in Annales de Médecine Vétérinaire (1997), 141

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

A all in vitro cloning technique was developed in wich embryos from the first cycle nuclear transfer (cloning) were used as blastomere donor for the second cycle nuclear transfer (re-cloning). Such method permitted to produce 14,5% of morulae and 14,9% of blastocysts after the first and second cycle of nuclear transfer, respectively. The rates of birth obtained after transfer of such embryos were 21,4% and 20,5% for first and second cyle respectively, corresponding to 6 and 5 calves for 28 and 24 transferred embryos. Unfortunately, gestation patholgies 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 detailRelationship of human follicular diameter with oocyte fertilization and development after in-vitro fertilization or intracytoplasmic sperm injection.
Ectors, Fabien ULg; Vanderzwalmen, P.; Van Hoeck, J. et al

in Human Reproduction (1997), 12(9), 2002-2005

The aim of this work was to evaluate the relationship between follicular size at the time of oocyte retrieval, and the subsequent oocyte competence to be fertilized and to develop in vitro. All the ... [more ▼]

The aim of this work was to evaluate the relationship between follicular size at the time of oocyte retrieval, and the subsequent oocyte competence to be fertilized and to develop in vitro. All the obtained oocytes were classified according to the corresponding volume of aspirated follicular fluid. Aspirated volume of follicular fluid <2 ml corresponded to a follicular diameter <16 mm and constituted the small size group. Volume of follicular fluid from 2 to 6 ml corresponded to a diameter from 16 to 23 mm and constituted the medium size group. The large size group contained follicles with diameter >23 mm and corresponded to an aspirated volume of follicular fluid of >6 ml. A progressive and significant increase in the rates of oocytes with a first polar body was observed from the small size group to the other groups and from the medium to the large size group: 75.3, 85.9 and 95.3% respectively. After classical in-vitro fertilization (IVF), significantly better rates of fertilization and development were obtained in the medium size group compared to the two other groups. Moreover, a positive relationship was observed between follicular diameter and rates of embryos scored as 'good' when oocytes were fertilized by intracytoplasmic sperm injection (ICSI). These results demonstrated that follicular size is positively related to the oocyte ability to be fertilized and to develop. Although oocytes from small follicles gave lower percentages of development probably due to partial oocyte incompetence, they allowed an increase in the total number of embryos scored as 'good'. [less ▲]

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See detailPregnancies after vitrification of human day 5 embryos
Vanderzwalmen, Pierre ULg; Delval, Alain; Chatziparasidou, A. et al

in Human Reproduction (1997), 12(suppl), 98

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See detailInterests of pregnancy follow-up in cows after embryo transfer : special focusing on IVP & NT
Ectors, Fabien ULg; Drion, Pierre ULg; Delval, A. et al

(1996, September 13)

In this report, pregnancies were obtained after extreme in vitro conditions- IVM/F/C of the donor embryos, - IVM, enucleation and artificial activation of the recipient oocytes, - nuclear transfer and ... [more ▼]

In this report, pregnancies were obtained after extreme in vitro conditions- IVM/F/C of the donor embryos, - IVM, enucleation and artificial activation of the recipient oocytes, - nuclear transfer and - IVC of the reconstituted embryos. Even if the incidence of this syndrome is relatively low after embryo transfer, a possible increasing of its occurence cannot be excluded in correlation with an incomplete maturation of oocytes at the time of fertilization, smaller follicles giving non competent or partially competent oocytes. An other explanation of this syndrome resulting in the higher variation in newborn calves weight may be also partly explained by the in vitro conditions. The gametes and/or embryos may be submitted to media containing embryotoxic substances. In the other hand, gametes and/or embryos may not found embryotrophic substances in the media like growth factors... Owing to this phenomenon, strict recommendations should be followed concerning rigorous follow-up of pregnancies obtained after transfer of IVM/IVF/IVC or cloned embryos by pregnancy proteins (PSPB, PAG...) or hormone (placental lactogen, estrone sulfate) assay and, after birth, macroscopic examinations of newborn, cord and caroncules. [less ▲]

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See detailAssesment of nuclear totipotency of fetal bovine diploid germ cells by nuclear transfer
Moens, André; Chesné, Patrick; Delhaize, Françoise et al

in Theriogenology (1996), 46

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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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