Background: Since the initiation of assisted reproduction techniques, several studies has been performed to improve treatment results by development of culture conditions like embryo oil and culture media used. In this study, two embryonic oils from different companies, Nidoil and Ovoil were examined.Method: In this study, 47 human embryos were used. All embryos were donated for research purposes by couples who had been treated at the clinic in Uppsala University Hospital. The embryos were divided into two groups, one group was cultured with Ovoil and the other with Nidoil.Results: There was no difference between the two oils, the embryo quality was the same in both groups.CONCLUSION: The result was expected because both oils had the same composition and purity.

La diapause embryonnaire se manifeste par un arrêt réversible du développement embryonnaire durant la période de préimplantation et induit un retard de l’implantation. Chez le vison américain, une diapause embryonnaire obligatoire caractérise chaque gestation. Si les mécanismes de contrôle de la diapause embryonnaire obligatoire chez cette espèce sont bien connus, le rôle utérin impliqué dans la réactivation de l’embryon demeure, quant à lui, encore inconnu. Le sujet de ce doctorat a consisté dans un premier temps à explorer l’environnement utérin à la sortie de la diapause embryonnaire afin de caractériser, dans un deuxième temps, les principaux acteurs utérins qui provoquent la réactivation de l’embryon. Nous avons effectué une analyse du transcriptome utérin à l’émergence de la diapause embryonnaire ce qui a permis de construire une librairie de 123 séquences d’ADNc utérines différentiellement exprimées à la réactivation de l’embryon et homologues à des séquences de gènes connues chez d’autres espèces. Ces gènes sont impliqués dans la régulation du métabolisme (25 %), de l’expression génique (21 %), de la transduction de signal (15 %), du cycle cellulaire (15 %), du transport (10 %) et de la structure cellulaire (9 %), reflétant ainsi d’importantes modifications utérines à la réactivation embryonnaire. Nous avons validé l’expression différentielle de dix gènes ainsi identifiés : GDF3 (growth and differentiation 3), ALCAM (activated leukocyte cell adhesion molecule), ADIPOR1 (adiponectin receptor 1), HMGN1 (high mobility group N1), TXNL1 (thioredoxin like 1), TGM2 (tissue transglutaminase 2), SPARC (secreted protein acidic rich in cystein), et trois gènes codant pour AZIN1 (antizyme inhibitor 1), ODC1 (ornithine decarboxylase 1) et SAT1 (spermidine/spermine N1-acetyltransferase), des enzymes impliquées dans la biosynthèse des polyamines. Le patron de l’expression spatio-temporel de SPARC et d’HMGN1 illustrent spécifiquement un remodelage tissulaire et de la chromatine au niveau utérin à la sortie de la diapause embryonnaire. Ayant mesuré une augmentation des concentrations utérines en polyamines à la reprise du développement embryonnaire, nous avons émis l’hypothèse que les polyamines seraient impliquées dans les événements menant à la sortie de la diapause. L’inhibition de la biosynthèse des polyamines par un traitement à l’ α-difluoromethylornithine (DFMO) a provoqué une diminution significative de la proliferation cellulaire dans les embryons à la réactivation, un retard du moment de l’implantation, mais n’a pas affecté le succès de la reproduction. De manière similaire, nous avons induit un état de dormance dans les cellules de trophoblaste de vison en présence DFMO dans le milieu de culture, et constaté que cet état était réversible. En conclusion, cette étude a non seulement ouvert de nouveaux horizons quant à la compréhension du rôle utérin dans les événements menant à la sortie de la diapause embryonnaire, mais a démontré pour la première fois, l’existence de facteurs utérins indispensables à la réactivation de l’embryon: les polyamines. / Embryonic diapause is characterized by a reversible arrest of blastocyst development prior to implantation and delay in implantation. In the American mink, embryonic diapause is a characteristic of each gestation. Although the mechanisms which control obligate embryonic diapause of this species are well known, the role of the uterus involved in blastocyst reactivation remains elusive. The subject of this doctoral research consisted first in exploring the uterine environment at the emergence of embryonic diapause in order to subsequently determine, the main factors in the uterus that provoke reactivation of the embryo. We have undertaken an analysis of the uterine transcriptome at the emergence of embryonic diapause which has enabled us to set up a library of 123 cDNA uterine sequences differentially expressed at blastocyst reactivation, and homologue gene sequences known in other species. Twenty-five percent of these genes are implicated in genetic expression, 15 % in cell signal transduction, 15 % in cell cycle, 10 % in transport and 9 % in cell structure. All of them reflect significant uterine modifications at blastocyst reactivation. We have validated differential expression of ten genes, identified as: GDF3 (growth and differentiation 3), ALCAM (activated leukocyte cell adhesion molecule), ADIPOR1 (adiponectin receptor 1), HMGN1 (high mobility group N1), TXNL1 (thioredoxine like 1), TGM2 (tissue transglutaminase 2), SPARC (secreted protein acidic rich in cystein), and three genes encoding for AZIN1 (antizyme inhibitor 1), ODC1 (ornithine decarboxylase 1) and SAT1 (spermidine/spermine N1-acetyltransferase), which are enzymes implicated in polyamine biosynthesis. The spatio-temporal expression patterns of SPARC and HMGN1 illustrate tissue and chromatin remodelling in the uterus at the termination of embryonic diapause. Having measured an increase in concentration of polyamines in the uterus at the resumption of blastocyst development, we have hypothetized that polyamines are implicated in the emergence of blastocysts from diapause. We inhibited polyamine biosynthesis in pregnant mink females during early blastocyst reactivation. The inhibition of polyamine biosynthesis through treatment with α-difluoromehtylornithine (DFMO) provoked a major reduction in cell proliferation in blastocysts at reactivation and a delay in the timing of implantation, but did not affect the success of reproduction. Similarly, we induced a reversible dormant state in cultured mink trophoblast cells traited with DFMO. To conclude, not only are results of this study a breakthrough in the understanding of the role of the uterus in stimulating at the emergence of blastocysts from embryonic diapause, but also, for the very first time, they indicate the existence of uterine factors, the polyamines, that are responsible for blastocysts reactivation.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Os mecanismos pelos quais a produção in vitro de embriões (PIVE) bovinos gera embriões com excessivo acúmulo lipídico, com elevado estresse celular e com reduzida criotolerância ainda são desconhecidos. Também permanece desconhecido quando essas alterações acontecem, se acontecem desde a maturação oocitária e o papel que as células do cumulus possuem neste mecanismo. O objetivo do presente trabalho foi estudar e comparar o metabolismo lipídico e homeostase celular, além dos perfis de miRNAs, durante a maturação oocitária e o desenvolvimento embrionário inicial in vivo e in vitro em bovinos. Para isso, o trabalho foi dividido em 4 estudos. No Estudo 1, intitulado \"A maturação in vitro gera complexos cumulus-oócitos metabolicamente desregulados e estressados em bovinos\" foram analisadas as células do cumulus e oócitos de complexos cumulus-oócitos (COCs) imaturos e maturados in vivo e in vitro. Foram realizadas análises de quantificação de lipídeos, espécies reativas de oxigênio (EROs), glutationa reduzida (GSH), razão ATP/ADP assim como expressão de mRNAs e miRNAs relacionados com as vias de metabolismo e homeostase celular. A partir dos dados obtidos neste estudo, concluímos que a maturação in vitro (MIV) provoca aumento de lipídeos no COC, diminuição de GSH e da atividade mitocondrial nos oócitos, acompanhado por uma desregulação massiva das vias relacionadas a metabolismo e homeostase nas células do cumulus da MIV. No Estudo 2, intitulado \"A proteína ligadora de ácidos graxos 3 (Fatty Acid Binding Protein 3 - FABP3) e as projeções transzonais estão envolvidas no acúmulo lipídico durante a maturação in vitro em oócitos bovinos\" foi constatado aumento do conteúdo lipídico e da expressão da FABP3 nas células do cumulus da MIV, quando comparado ao sistema in vivo. Ainda, imunolocalizamos a FABP3 dentro das projeções transzonais (TZPs) e verificamos um aumento concomitante da FABP3 e dos lipídeos oocitários nas primeiras 9 horas da MIV. Mediante a remoção das TZPs às 9 horas da MIV e consequente diminuição lipídica observada no oócito, concluímos que existe um possível transporte de ácidos graxos a partir das células do cumulus até o oócito mediante FABP3 e TZPs. No Estudo 3, intitulado \"Alterações no metabolismo lipídico e homeostase celular entre embriões bovinos produzidos in vivo e in vitro\", verificamos que, mesmo utilizando um cultivo in vitro com baixa tensão de oxigênio e sem soro, os blastocistos da PIVE possuem maiores níveis de lipídeos e EROs que aqueles produzidos in vivo. Além disso, constatamos que essas alterações nos lipídeos durante a PIVE não estão acompanhadas de alterações de expressão, porém, existe um aumento na expressão de genes relacionados com estresse. No último estudo, \"O sistema in vitro altera o perfil de miRNAs durante a maturação oocitária e desenvolvimento embrionário inicial em bovino\", constatamos as diferenças no perfil de miRNAs e nas vias reguladas por estes nas células do cumulus e oócitos maturados in vivo e in vitro e em blastocistos produzidos in vivo e in vitro. Verificamos uma maior regulação por miRNAs durante a maturação nas células do cumulus comparado ao oócito. Além do mais, tanto no COC quanto nos blastocistos, os miRNAs mostraram regular vias importantes do metabolismo, comunicação celular e vias de sinalização importantes para a maturação e desenvolvimento embrionário inicial. Conjuntamente, este trabalho permitiu elucidar as diferenças que a PIVE provoca no metabolismo e homeostase celular e na expressão de miRNAs. / The mechanism through which in vitro embryo production (IVEP) generates embryos with higher lipid accumulation, overstressed and with reduced cryotolerance is unknown. It is also unknown when these alterations take place, if occurs since the oocyte maturation and the role of cumulus cells in this mechanism are also unknown. The aim of the present work was to study and compare the lipid metabolism and cellular homeostasis, as well as the miRNAs profile during oocyte maturation and early in vivo and in vitro embryo development in bovines. For that, the present work was divided in 4 studies. In Study 1, entitled \"in vitro maturation generates metabolically disrupted and overstressed cumulus-oocyte complexes in bovines\" cumulus cells and oocytes from immature and in vivo and in vitro matured cumulus-cells complexes (COC) were analyzed. Analysis of lipid stores, oxygen reactive species (ROS), reduced glutathione and ATP/ADP ratio quantification, as well as mRNAs and miRNAs involved with metabolism and cellular homeostasis pathways were performed. From the obtained data in this study, we concluded that in vitro maturation (IVM) leads to an increase of lipids in the COC, a decrease of oocyte GSH and mitochondrial activity, as well as a massive deregulation in metabolism and homeostasis related pathways in MIV cumuls cells. In Study 2, \"Fatty Acid Binding Protein 3 and transzonal projections are involved on lipid accumulation during in vitro maturation in bovine oocytes\" we observed an increase of lipid accumulation and FABP3 expression in MIV cumulus cells when compared to the in vivo system. Furthermore, we immunolocalized the FABP3 inside the transzonal projections (TZPs) and verified a concomitant increase of FABP3 and oocyte lipids on the first 9 hours of MIV. By removing the TZPs at 9 hours of MIV and by the consequent lipid decrease observed in the oocyte, we concluded that there is a possible traffic of fatty acids from the cumulus cells to the oocyte mediated by FABP3 and TZPs. In Study 3, entitled \"Alterations in lipid metabolism and cellular homeostasis between in vivo and in vitro produced bovine embryos\", we observed that, even though under serum free and low oxygen tension used during in vitro culture was used, IVP blastocysts had higher lipid and ROS levels than the counterparts produced in vivo. Moreover, we found that these lipid alterations during IVP are not followed by corresponding genes expression alterations, however, there is an increase of the expression of stress related genes. In the last study, \"in vitro system alters miRNAs profile during oocyte maturation and early embryo development in bovines\", we observed differences in miRNAs profiles and in pathways modulated by them in in vivo and in vitro matured cumulus cells and oocytes and in in vivo and in vitro produced blastocysts. We observed an intense miRNAs regulation during maturation in cumulus cells when compared to the oocyte. Furthermore, in both COC and blastocysts, miRNAs regulated important metabolism, cellular communication pathways, as well as important signaling pathways for maturation and early embryo development. Taken together, the findings of the present work allowed us to elucidate the differences caused by IVEP on cell metabolism and homeostasis as well as on miRNAs expression.

Embriões bovinos produzidos in vitro (PIV) apresentam diferenças quando comparados aos produzidos in vivo. Esta particularidade reduz as taxas de viabilidade in vitro e in vivo após a criopreservação, limitando o emprego comercial da preservação dos embriões PIV. Várias estratégias vêm sendo propostas para aumentar a viabilidade e desenvolvimento desses embriões criopreservados. Alguns estudos utilizam a exposição dos embriões a um estresse subletal, como a alta pressão hidrostática (HHP), previamente a procedimentos que reduzem a viabilidade embrionária, o que aumenta a tolerância desses indivíduos à criopreservação. Os objetivos deste experimento foram determinar as taxas de viabilidade de blastocistos bovinos PIV previamente expostos à alta pressão gasosa (HGP) de 27,5 MPa por 120 min e após submetidos à congelação ou vitrificação. A avaliação da viabilidade foi mediante determinação das taxas de re-expansão e eclosão após criopreservação.Oócitos morfologicamente viáveis obtidos a partir de ovários de frigorífico foram maturados in vitro durante 24 h a 38,5 °C, em atmosfera de 5% de CO2 com umidade relativa do ar saturada e fecundados (dia 0) com sêmen criopreservado capacitado in vitro Após 20 h, os presuntivos zigotos foram submetidos a cultivo in vitro em meio SOF condicionado a 38,5 °C, em atmosfera de 5% de CO2, 5% O2 e 90% N2, com umidade relativa do ar saturada. Os blastocistos (dia 7) foram divididos aleatoriamente em 4 grupos: expostos à HGP e congelados, PC; controle congelação, CC; expostos à HGP e vitrificados, PV; controle vitrificação, CV. Os embriões foram expostos ou não à HGP de 27,5 MPa por 120 min e em seguida colocados em cultivo por 120 min. Após esse período os blastocistos foram submetidos à congelação ou à vitrificação. A taxa de re-expansão dos blastocistos avaliada em 24 h do grupo CV (59,6%) foi maior que a dos embriões dos grupos CC (45,2%) e PC (46,3%) (P<0,05), mas não diferiu da taxa de re-expansão dos embriões do grupo PV (48,1%). As taxas de eclosão foram: PC, 21,5%; CC, 24,6%; PV, 35,3%; CV, 30,8%. Os blastocistos do grupo PV apresentaram maiores taxas de eclosão do que os embriões do grupo PC. Em conclusão, o tratamento com HGP não interferiu no desenvolvimento in vitro dos blastocistos que foram submetidos à congelação ou à vitrificação. Levando em consideração os blastocistos eclodidos sobre o total de re-expandidos, o tratamento com HGP incrementou a taxa de eclosão in vitro dos embriões que foram submetidos à vitrificação. / In vitro bovine embryos (IVP) present differences when compared to those produced in vivo. This particularity reduces in vitro and in vivo survival rates after cryopreservation, limiting the commercial use of IVP embryos preservation. Several strategies have been proposed to increase viability and development of these cryopreserved embryos. Some studies use embryo exposure to sublethal stress prior to in vitro procedures, such as high hydrostatic pressure (HHP), which increases tolerance of these individuals to a new stressor, such as cryopreservation. Objectives of this experiment were to determine viability rates of bovine blastocysts produced in vitro previously exposed to high gaseous pressure (HGP) of 27.5 MPa for 120 minutes and after subjected to freezing or vitrification. Morphologically viable oocytes obtained from bovine ovaries were matured in vitro for 24 hours at 38.5°C in 5% CO2 atmosphere with saturated air humidity and in vitro fertilized (day 0) with cryopreserved semen (inseminating dose 1x106 / ml) After 20 hours, presumptive zygotes were cultured in vitro at 38.5°C in an atmosphere of 5% CO2, 5% O2 e 90% N2 with saturated air humidity. Blastocysts obtained on day 7 were divided into 4 groups: exposed to HGP and frozen (FP); freezing control (FC); exposed to HGP and vitrified (VP); vitrification control (VC). These groups were exposed or not to 27.5 MPa HGP for 120 minutes then in vitro cultured for more 120 min. After this period, blastocysts were subjected to freezing or vitrification. Re-expansion rate was higher (P<0.05) for CV (59,6%) compared to CC (45,2%) and CV (46,3%), not differing from PV (48,1%). Blastocysts from group VP presented higher hatching rates than embryos from group FP (P<0.05) (35,3% vs. 21,5%, respectively). In conclusion, exposure of blastocysts to HGP before vitrification or conventional freezing did not interfered on in vitro embryo survival rates. However, considering hatched blastocysts over the total re-expanded, HGP increased hatching rates of vitrified embryos.

In the general population, one in five couples experiences difficulty in conceiving a child. The role of obesity on women’s fecundity has become a focus of attention in recent years. Successful treatment of infertility through Assisted Reproductive Technology (ART) is also compromised by the presence of obesity, which occurs in 30 % of women seeking treatment. A negative correlation exists between increased body mass index (BMI) and the number of collected oocytes and a lower birth rate after ART. Furthermore, a number of studies have established that weight loss improves natural conception rates in overweight women. Whether weight management can improve success rates in overweight / obese women undergoing in vitro fertilisation (IVF) has not been studied. The purpose of this project was to explore the role of short–term weight loss on potential pregnancy outcomes in overweight / obese women undergoing IVF programme. However, to establish this relationship, we proposed to carry out two studies to assess the following: (I) The feasibility of very low calorie diet (VLCD) during IVF treatment with respect to duration, level of restriction and tolerability of the diet during hormonal down regulation in women (Chapter 2). (II) How energy restriction may affect the quality of an early embryo in diet - induced obese mice with respect to various body weight and caloric intake (Chapter 3). In study (I), women preferred a shorter dietary intervention with greater energy restriction (456 kcal per day) to gradual energy restriction (1200 kcal / day for the first week, and afterward, 456 kcal / day) prior to oocyte transfer. Women were able to comply with the VLCD during IVF treatment and both dietary groups achieved a significant weight loss (mean 6.3 %). In study (II), by using obese mice, the effect of rapid weight loss (mean 12 %) was observed after 5 days of energy restriction. Ovulation rate was greater in the Obese group (HFD) (55.6%) and equal in both Control (CD) and Energy Restricted (HF / ER) (44.4 %) groups. The HF / ER group showed higher fertilisation rate (80 %) than HFD and CD (55% and 45.5%, correspondingly). The blastocyst stage was reached by half of the cultured embryos in both HF / ER and HFD groups and 33 % in the CD group. The quality of embryos that completed blastocyst formation did not differ between groups. However, postfertilisation development in females fed a high fat diet was slower compared to CD and HF / ER groups. In conclusion, this work illustrated a weight management prior conception and use of VLCD during IVF treatment in clinical study needs further investigation with regard to the dietary duration, level of energy restriction and how this combination will influence IVF treatment outcomes. Furthermore, as we were unable to determine the question of how the dietary intervention affects the quality of oocytes and the animal study illustrated a promising result, thus further studies are required. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311579 / Thesis (M.Med.Sc.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2008

In the general population, one in five couples experiences difficulty in conceiving a child. The role of obesity on women’s fecundity has become a focus of attention in recent years. Successful treatment of infertility through Assisted Reproductive Technology (ART) is also compromised by the presence of obesity, which occurs in 30 % of women seeking treatment. A negative correlation exists between increased body mass index (BMI) and the number of collected oocytes and a lower birth rate after ART. Furthermore, a number of studies have established that weight loss improves natural conception rates in overweight women. Whether weight management can improve success rates in overweight / obese women undergoing in vitro fertilisation (IVF) has not been studied. The purpose of this project was to explore the role of short–term weight loss on potential pregnancy outcomes in overweight / obese women undergoing IVF programme. However, to establish this relationship, we proposed to carry out two studies to assess the following: (I) The feasibility of very low calorie diet (VLCD) during IVF treatment with respect to duration, level of restriction and tolerability of the diet during hormonal down regulation in women (Chapter 2). (II) How energy restriction may affect the quality of an early embryo in diet - induced obese mice with respect to various body weight and caloric intake (Chapter 3). In study (I), women preferred a shorter dietary intervention with greater energy restriction (456 kcal per day) to gradual energy restriction (1200 kcal / day for the first week, and afterward, 456 kcal / day) prior to oocyte transfer. Women were able to comply with the VLCD during IVF treatment and both dietary groups achieved a significant weight loss (mean 6.3 %). In study (II), by using obese mice, the effect of rapid weight loss (mean 12 %) was observed after 5 days of energy restriction. Ovulation rate was greater in the Obese group (HFD) (55.6%) and equal in both Control (CD) and Energy Restricted (HF / ER) (44.4 %) groups. The HF / ER group showed higher fertilisation rate (80 %) than HFD and CD (55% and 45.5%, correspondingly). The blastocyst stage was reached by half of the cultured embryos in both HF / ER and HFD groups and 33 % in the CD group. The quality of embryos that completed blastocyst formation did not differ between groups. However, postfertilisation development in females fed a high fat diet was slower compared to CD and HF / ER groups. In conclusion, this work illustrated a weight management prior conception and use of VLCD during IVF treatment in clinical study needs further investigation with regard to the dietary duration, level of energy restriction and how this combination will influence IVF treatment outcomes. Furthermore, as we were unable to determine the question of how the dietary intervention affects the quality of oocytes and the animal study illustrated a promising result, thus further studies are required. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311579 / Thesis (M.Med.Sc.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2008

Para reducir la incidencia de las penetraciones polispérmicas en los sistemas de fecundación in vitro porcina (FIV), los objetivos del presente trabajo fueron estudiar: 1) el efecto de tres volúmenes de medio de coincubación (2, 1 y 0'1 ml) y tres números de ovocitos (50, 30 y 15), inseminados con 6 x 105 espermatozoides /ml (primera experiencia) y 2000:1 espermatozoides:ovocito (segunda experiencia); 2) el efecto de la presencia de células del cumulus durante la FIV de ovocitos inseminados con diferentes ratios espermatozoides:ovocito (2000:1; 3000:1; 4000:1, 6000:1 y 8000:1), en 0'1 ml de medio de fecundación, con 30 ovocitos. Ovocitos madurados in vitro y denudados inseminados con 2000 espermatozoides por ovocito fueron el grupo control; y 3) el efecto de tiempos cortos de coincubación ovocitos-espermatozoides durante la FIV (10, 30 y 60 min) sobre la eficiencia de la FIV porcina. / To decrease the high incidence of polyspermy penetration of porcine oocytes fertilized in vitro (IVF), the aim of this study was to evaluate: 1) the effect of three volume of co-incubation medium (2, 1 and 0.1 ml) and three number of oocytes (50, 30 and 15), inseminated with 6 x l05 sperm/ml (first experience) and 2000:1 spermatozoa:oocyte (second experience); 2) the effect of cumulus cells during IVF of oocytes inseminated with different espermatozoa:oocytes rates (2000: 1, 3000: 1, 4000: 1, 6000: 1 and 8000: 1), in 0.1 ml of volume of IVF medium, with 30 oocytes. Denuded matured oocytes inseminated with 2000 spermatozoa:oocyte were the control group; and 3) the effect of short-times that oocytes are exposed to the sperm during IVF (10, 30 and 60 min) on the efficiency of pig IVF.

No description available.

La diapause embryonnaire se manifeste par un arrêt réversible du développement embryonnaire durant la période de préimplantation et induit un retard de l’implantation. Chez le vison américain, une diapause embryonnaire obligatoire caractérise chaque gestation. Si les mécanismes de contrôle de la diapause embryonnaire obligatoire chez cette espèce sont bien connus, le rôle utérin impliqué dans la réactivation de l’embryon demeure, quant à lui, encore inconnu. Le sujet de ce doctorat a consisté dans un premier temps à explorer l’environnement utérin à la sortie de la diapause embryonnaire afin de caractériser, dans un deuxième temps, les principaux acteurs utérins qui provoquent la réactivation de l’embryon. Nous avons effectué une analyse du transcriptome utérin à l’émergence de la diapause embryonnaire ce qui a permis de construire une librairie de 123 séquences d’ADNc utérines différentiellement exprimées à la réactivation de l’embryon et homologues à des séquences de gènes connues chez d’autres espèces. Ces gènes sont impliqués dans la régulation du métabolisme (25 %), de l’expression génique (21 %), de la transduction de signal (15 %), du cycle cellulaire (15 %), du transport (10 %) et de la structure cellulaire (9 %), reflétant ainsi d’importantes modifications utérines à la réactivation embryonnaire. Nous avons validé l’expression différentielle de dix gènes ainsi identifiés : GDF3 (growth and differentiation 3), ALCAM (activated leukocyte cell adhesion molecule), ADIPOR1 (adiponectin receptor 1), HMGN1 (high mobility group N1), TXNL1 (thioredoxin like 1), TGM2 (tissue transglutaminase 2), SPARC (secreted protein acidic rich in cystein), et trois gènes codant pour AZIN1 (antizyme inhibitor 1), ODC1 (ornithine decarboxylase 1) et SAT1 (spermidine/spermine N1-acetyltransferase), des enzymes impliquées dans la biosynthèse des polyamines. Le patron de l’expression spatio-temporel de SPARC et d’HMGN1 illustrent spécifiquement un remodelage tissulaire et de la chromatine au niveau utérin à la sortie de la diapause embryonnaire. Ayant mesuré une augmentation des concentrations utérines en polyamines à la reprise du développement embryonnaire, nous avons émis l’hypothèse que les polyamines seraient impliquées dans les événements menant à la sortie de la diapause. L’inhibition de la biosynthèse des polyamines par un traitement à l’ α-difluoromethylornithine (DFMO) a provoqué une diminution significative de la proliferation cellulaire dans les embryons à la réactivation, un retard du moment de l’implantation, mais n’a pas affecté le succès de la reproduction. De manière similaire, nous avons induit un état de dormance dans les cellules de trophoblaste de vison en présence DFMO dans le milieu de culture, et constaté que cet état était réversible. En conclusion, cette étude a non seulement ouvert de nouveaux horizons quant à la compréhension du rôle utérin dans les événements menant à la sortie de la diapause embryonnaire, mais a démontré pour la première fois, l’existence de facteurs utérins indispensables à la réactivation de l’embryon: les polyamines. / Embryonic diapause is characterized by a reversible arrest of blastocyst development prior to implantation and delay in implantation. In the American mink, embryonic diapause is a characteristic of each gestation. Although the mechanisms which control obligate embryonic diapause of this species are well known, the role of the uterus involved in blastocyst reactivation remains elusive. The subject of this doctoral research consisted first in exploring the uterine environment at the emergence of embryonic diapause in order to subsequently determine, the main factors in the uterus that provoke reactivation of the embryo. We have undertaken an analysis of the uterine transcriptome at the emergence of embryonic diapause which has enabled us to set up a library of 123 cDNA uterine sequences differentially expressed at blastocyst reactivation, and homologue gene sequences known in other species. Twenty-five percent of these genes are implicated in genetic expression, 15 % in cell signal transduction, 15 % in cell cycle, 10 % in transport and 9 % in cell structure. All of them reflect significant uterine modifications at blastocyst reactivation. We have validated differential expression of ten genes, identified as: GDF3 (growth and differentiation 3), ALCAM (activated leukocyte cell adhesion molecule), ADIPOR1 (adiponectin receptor 1), HMGN1 (high mobility group N1), TXNL1 (thioredoxine like 1), TGM2 (tissue transglutaminase 2), SPARC (secreted protein acidic rich in cystein), and three genes encoding for AZIN1 (antizyme inhibitor 1), ODC1 (ornithine decarboxylase 1) and SAT1 (spermidine/spermine N1-acetyltransferase), which are enzymes implicated in polyamine biosynthesis. The spatio-temporal expression patterns of SPARC and HMGN1 illustrate tissue and chromatin remodelling in the uterus at the termination of embryonic diapause. Having measured an increase in concentration of polyamines in the uterus at the resumption of blastocyst development, we have hypothetized that polyamines are implicated in the emergence of blastocysts from diapause. We inhibited polyamine biosynthesis in pregnant mink females during early blastocyst reactivation. The inhibition of polyamine biosynthesis through treatment with α-difluoromehtylornithine (DFMO) provoked a major reduction in cell proliferation in blastocysts at reactivation and a delay in the timing of implantation, but did not affect the success of reproduction. Similarly, we induced a reversible dormant state in cultured mink trophoblast cells traited with DFMO. To conclude, not only are results of this study a breakthrough in the understanding of the role of the uterus in stimulating at the emergence of blastocysts from embryonic diapause, but also, for the very first time, they indicate the existence of uterine factors, the polyamines, that are responsible for blastocysts reactivation.