Mammalian oogenesis is characterized by alternating periods of active meiotic progression and intermittent, long periods of meiotic arrest. The oocyte undergoes major growth and developmental processes in the period prior to ovulation. At the time of birth, most oocytes are arrested in the dictyate stage of meiosis; they remain quiescent for an indeterminate period until they begin growing in response to as yet undefined local signals [1]. From the beginning of the growth phase until the time of ovulation, oocytes increase in volume by at least two orders of magnitude and during this time exhibit intense metabolic activity. Resumption of meiosis only occurs in a ful ly grown, meiotically competent oocyte after the luteinizing hormone (LH) surge when oocytes undergo germina l ves ic le breakdown (GVBD), complete first meiosis, and mature to metaphase II. In many mammals such as the mouse, pig, cow and man, completion of meiosis is dependent on fertilization that triggers progression to anaphase II, and to the first mitotic interphase with formation of female and male pronuclei. The process of maturation encompasses a complex series of molecular and structural events, culminating in the arrest of the oocyte chromosomes on the metaphase II plate in anticipation of sperm penetration and activation for fertilization. This review will focus on the biology of oocyte maturation and the potential relevance of maturation of human oocytes in vitro to reproductive medicine.
{"title":"Oocyte Maturation in Humans: the Potential Relevance to Reproductive Medicine","authors":"Y. Yoshimura","doi":"10.1274/JMOR.20.86","DOIUrl":"https://doi.org/10.1274/JMOR.20.86","url":null,"abstract":"Mammalian oogenesis is characterized by alternating periods of active meiotic progression and intermittent, long periods of meiotic arrest. The oocyte undergoes major growth and developmental processes in the period prior to ovulation. At the time of birth, most oocytes are arrested in the dictyate stage of meiosis; they remain quiescent for an indeterminate period until they begin growing in response to as yet undefined local signals [1]. From the beginning of the growth phase until the time of ovulation, oocytes increase in volume by at least two orders of magnitude and during this time exhibit intense metabolic activity. Resumption of meiosis only occurs in a ful ly grown, meiotically competent oocyte after the luteinizing hormone (LH) surge when oocytes undergo germina l ves ic le breakdown (GVBD), complete first meiosis, and mature to metaphase II. In many mammals such as the mouse, pig, cow and man, completion of meiosis is dependent on fertilization that triggers progression to anaphase II, and to the first mitotic interphase with formation of female and male pronuclei. The process of maturation encompasses a complex series of molecular and structural events, culminating in the arrest of the oocyte chromosomes on the metaphase II plate in anticipation of sperm penetration and activation for fertilization. This review will focus on the biology of oocyte maturation and the potential relevance of maturation of human oocytes in vitro to reproductive medicine.","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"40 1","pages":"86-92"},"PeriodicalIF":0.0,"publicationDate":"2003-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79611452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although the ovaries of mammals contain thousands or millions of immature oocytes, few of these ever mature to the point at which reproduction in vivo is possible. Ovarian oocytes therefore constitute a large and potentially valuable resource for clinical and zoological application. However, the developmental program of oocytes is not fully understood. If oogenesis is completed in vitro, such in vitro systems are available for applicative and fundamental studies. In this review, focused on mouse oogenesis, we describe currently optimal in vitro systems for the production of functional oocytes. Finally, some potential future applications of these in vitro systems are discussed.
{"title":"Production of Functional Oocytes In Vitro","authors":"Y. Obata, T. Kono","doi":"10.1274/JMOR.20.74","DOIUrl":"https://doi.org/10.1274/JMOR.20.74","url":null,"abstract":"Although the ovaries of mammals contain thousands or millions of immature oocytes, few of these ever mature to the point at which reproduction in vivo is possible. Ovarian oocytes therefore constitute a large and potentially valuable resource for clinical and zoological application. However, the developmental program of oocytes is not fully understood. If oogenesis is completed in vitro, such in vitro systems are available for applicative and fundamental studies. In this review, focused on mouse oogenesis, we describe currently optimal in vitro systems for the production of functional oocytes. Finally, some potential future applications of these in vitro systems are discussed.","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"268 1","pages":"74-77"},"PeriodicalIF":0.0,"publicationDate":"2003-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77168651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present study, we investigated the role of actin filaments in the blastocoel (BC) of bovine blastocysts produced in vitro by using cytochalasin-D (CD), an inhibitor of actin polymerization. Blastocysts classified as good or poor based on their morphological normality were exposed to 2 μM CD for 1.5-2 hr. After incubation, the presence or absence of BC was observed, and the re-expansion rate was assessed after transferring CD-treated blastocysts with collapsed BC to a non-CD medium. Ultrastructural observation was also undertaken using a transmission electron microscope (TEM). The remaining blastocysts were immersed in a hypotonic solution of sodium citrate so that the cells could be counted to confirm the classification grade of blastocysts in this study. The percent of maintained BC under the presence of CD in the good group was significantly lower (P<0.05) than that in the poor group (3.3% versus 27.7%, respectively). The average cell number of blastocysts in the good group was significantly more (P<0.05) than that in the poor group. In addition, when the blastocysts with shrunken BC in both groups were cultured, re-expansion rates in the good and poor groups were 83.3 and 75.0%, respectively, and no significant difference was observed between groups. Based on observation of the ultrastructure with TEM, the microvilli on the surface of some trophoblast cells of some blastocysts in the poor group in the presence of CD showed a translucent matrix, and their electron density was low compared with that of trophoblast cells of blastocysts in the good and non-treated (control) groups. However, the electron density of microvilli after removal of CD in the poor group increased to a level comparable to those of the good and control groups. These results suggest that polymerizing actin may be required to sustain the blastocoel and microvilli of blastocysts produced in vitro. However, in poor grade blastocysts, the polymerization ability of actin present in the filamentous form in the microvilli in some cells might be lower than that in good grade blastocysts.
{"title":"Effects of Cytochalasin-D on the Maintenance of Blastocoels of Bovine Blastocysts Produced In Vitro","authors":"Y. Tsuzuki, K. Ashizawa, N. Fujihara","doi":"10.1274/JMOR.20.106","DOIUrl":"https://doi.org/10.1274/JMOR.20.106","url":null,"abstract":"In the present study, we investigated the role of actin filaments in the blastocoel (BC) of bovine blastocysts produced in vitro by using cytochalasin-D (CD), an inhibitor of actin polymerization. Blastocysts classified as good or poor based on their morphological normality were exposed to 2 μM CD for 1.5-2 hr. After incubation, the presence or absence of BC was observed, and the re-expansion rate was assessed after transferring CD-treated blastocysts with collapsed BC to a non-CD medium. Ultrastructural observation was also undertaken using a transmission electron microscope (TEM). The remaining blastocysts were immersed in a hypotonic solution of sodium citrate so that the cells could be counted to confirm the classification grade of blastocysts in this study. The percent of maintained BC under the presence of CD in the good group was significantly lower (P<0.05) than that in the poor group (3.3% versus 27.7%, respectively). The average cell number of blastocysts in the good group was significantly more (P<0.05) than that in the poor group. In addition, when the blastocysts with shrunken BC in both groups were cultured, re-expansion rates in the good and poor groups were 83.3 and 75.0%, respectively, and no significant difference was observed between groups. Based on observation of the ultrastructure with TEM, the microvilli on the surface of some trophoblast cells of some blastocysts in the poor group in the presence of CD showed a translucent matrix, and their electron density was low compared with that of trophoblast cells of blastocysts in the good and non-treated (control) groups. However, the electron density of microvilli after removal of CD in the poor group increased to a level comparable to those of the good and control groups. These results suggest that polymerizing actin may be required to sustain the blastocoel and microvilli of blastocysts produced in vitro. However, in poor grade blastocysts, the polymerization ability of actin present in the filamentous form in the microvilli in some cells might be lower than that in good grade blastocysts.","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"19 1","pages":"106-112"},"PeriodicalIF":0.0,"publicationDate":"2003-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78794404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oocyte maturation is regulated by maturation/M-phase promoting factor (MPF), a crucial M-phase regulating enzyme composed of a catalytic subunit, p34 cdc2 , and a regulatory subunit, cyclin B. The amount of p34 cdc2 is almost constant during oocyte maturation, and the amount of cyclin B is the principal factor determining MPF activity [1]. The presence of two types of cyclin B, cyclin B1 and cyclin B2, has been shown in vertebrates. In human cells, cyclin B1 can cause chromosome condensation, reorganization of the microtubules, and disassembly of the nuclear lamina and of the Golgi apparatus, whereas the role of cyclin B2 is restricted only to disassembly of the Golgi apparatus [2, 3]. In maturing oocytes, differences between cyclin B1 and cyclin B2 functions have been reported in the first meiotic spindle formation and the second metaphase arrest in frog and mouse oocytes, respectively [4(cid:150)6]. In our laboratory, we have studied cyclin B functions during porcine oocyte maturation for the past several years. The present review describes our recent observations with regard to protein levels, intracellular localizations and roles of cyclin B. We focus here on the differences between cyclin B1 and cyclin B2. density of
{"title":"Localization and Function of Cyclin B1 and Cyclin B2 during Porcine Oocyte Maturation","authors":"Takao Kuroda, K. Naito","doi":"10.1274/JMOR.20.93","DOIUrl":"https://doi.org/10.1274/JMOR.20.93","url":null,"abstract":"Oocyte maturation is regulated by maturation/M-phase promoting factor (MPF), a crucial M-phase regulating enzyme composed of a catalytic subunit, p34 cdc2 , and a regulatory subunit, cyclin B. The amount of p34 cdc2 is almost constant during oocyte maturation, and the amount of cyclin B is the principal factor determining MPF activity [1]. The presence of two types of cyclin B, cyclin B1 and cyclin B2, has been shown in vertebrates. In human cells, cyclin B1 can cause chromosome condensation, reorganization of the microtubules, and disassembly of the nuclear lamina and of the Golgi apparatus, whereas the role of cyclin B2 is restricted only to disassembly of the Golgi apparatus [2, 3]. In maturing oocytes, differences between cyclin B1 and cyclin B2 functions have been reported in the first meiotic spindle formation and the second metaphase arrest in frog and mouse oocytes, respectively [4(cid:150)6]. In our laboratory, we have studied cyclin B functions during porcine oocyte maturation for the past several years. The present review describes our recent observations with regard to protein levels, intracellular localizations and roles of cyclin B. We focus here on the differences between cyclin B1 and cyclin B2. density of","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"28 1","pages":"93-98"},"PeriodicalIF":0.0,"publicationDate":"2003-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77590300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Hosoe, T. Furusawa, F. Inoue, M. Sakatani, T. Tokunaga, R. Schultz, Masashi Takahashi
Double stranded RNA (dsRNA) interference is a useful tool for interfering with gene function by promoting the sequence-dependent degradation of targeted mRNA in several organisms. In the present study, in order to confirm and improve the effect of dsRNA, we investigated an inhibitory effect of dsRNA on both transient and stable gene expression of enhanced green fluorescent protein (EGFP) in mouse preimplantation embryos. In the transient expression system, the rates of fluorescent embryos were significantly decreased by co-injection of EGFP dsRNA and EGFP expression vector fragment into the pronucleus of zygotes. In the stable expression system, EGFP expression in transgenic embryos was significantly decreased by injection of EGFP dsRNA into both the pronucleus and cytoplasm of zygotes, but, cytoplasmic injection caused a more significant EGFP inhibition than pronuclear injection. In quantitative PCR analysis, the expression of the EGFP gene was also inhibited by dsRNA injection, whereas the endogenous gene expression was not affected. These data suggest that dsRNA can inhibit the specific gene expression without affecting the development and expression of other genes.
{"title":"Specific Inhibition of Transient and Stable EGFP Gene Expression by Double Stranded RNA Interference in Mouse Preimplantation Embryos","authors":"M. Hosoe, T. Furusawa, F. Inoue, M. Sakatani, T. Tokunaga, R. Schultz, Masashi Takahashi","doi":"10.1274/JMOR.20.99","DOIUrl":"https://doi.org/10.1274/JMOR.20.99","url":null,"abstract":"Double stranded RNA (dsRNA) interference is a useful tool for interfering with gene function by promoting the sequence-dependent degradation of targeted mRNA in several organisms. In the present study, in order to confirm and improve the effect of dsRNA, we investigated an inhibitory effect of dsRNA on both transient and stable gene expression of enhanced green fluorescent protein (EGFP) in mouse preimplantation embryos. In the transient expression system, the rates of fluorescent embryos were significantly decreased by co-injection of EGFP dsRNA and EGFP expression vector fragment into the pronucleus of zygotes. In the stable expression system, EGFP expression in transgenic embryos was significantly decreased by injection of EGFP dsRNA into both the pronucleus and cytoplasm of zygotes, but, cytoplasmic injection caused a more significant EGFP inhibition than pronuclear injection. In quantitative PCR analysis, the expression of the EGFP gene was also inhibited by dsRNA injection, whereas the endogenous gene expression was not affected. These data suggest that dsRNA can inhibit the specific gene expression without affecting the development and expression of other genes.","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"42 1","pages":"99-105"},"PeriodicalIF":0.0,"publicationDate":"2003-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80794644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A huge number o f sma l l oocy tes a re contained in the ovaries of the pig and cow. A small number of them grow from the minimal size of 30 μm in diameter to the final size of 120125 μm, then mature, and are ovulated. A large number of the remaining oocytes do not enter the growth phase or degenerate in the ovary. Oocyte growth takes a long time and is coordinated with surrounding follicle cells. During the growth phase, oocytes are required to be arrested at prophase I (GV stage), and to acquire the meiotic competence to mature to metaphase II. IVG culture systems have been developed for domestic species, although they are still being improved. IVG culture systems for small oocytes are expected to provide a new source of oocytes for livestock production as well as a better understanding of the basic mechanisms of oogenesis/folliculogenesis in the ovary.
{"title":"In Vitro Growth of Oocytes from Domestic Species","authors":"T. Miyano, Y. Hirao","doi":"10.1274/JMOR.20.78","DOIUrl":"https://doi.org/10.1274/JMOR.20.78","url":null,"abstract":"A huge number o f sma l l oocy tes a re contained in the ovaries of the pig and cow. A small number of them grow from the minimal size of 30 μm in diameter to the final size of 120125 μm, then mature, and are ovulated. A large number of the remaining oocytes do not enter the growth phase or degenerate in the ovary. Oocyte growth takes a long time and is coordinated with surrounding follicle cells. During the growth phase, oocytes are required to be arrested at prophase I (GV stage), and to acquire the meiotic competence to mature to metaphase II. IVG culture systems have been developed for domestic species, although they are still being improved. IVG culture systems for small oocytes are expected to provide a new source of oocytes for livestock production as well as a better understanding of the basic mechanisms of oogenesis/folliculogenesis in the ovary.","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"7 1","pages":"78-85"},"PeriodicalIF":0.0,"publicationDate":"2003-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83042446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mouse p ronuc lear em bryos we re cryopreserved by a simple and safe vitrification method. In the process, Vitrification Media VT101, Thawing Media VT 102 (KITAZATO. Co. Japan) and the embryos were loaded into a straw; then they were cryopreserved. Different loading methods were examined to determine the safety levels of crystallization for the embryos survival after thawing. The best condition attained, after thawing, was a 75% embryo survived rate of which 66% developed to the two-cell stage, 71% developed to the morula stage and 27% developed to the blastosyst stage. This development of embryos after vitrification was not significantly different to that of a control group without freezing and thawing. The vitrification method was considered to protect embryos against various infections via liquid nitrogen during cryopreservation. It is expected that the method can be applied to human embryos.
{"title":"A Vitrification Method by Means of a Straw to Prevent Infections in Mouse Pronuclear Embryos","authors":"M. Kumon, Y. Kumasako, T. Utsunomiya, Y. Araki","doi":"10.1274/JMOR.20.124","DOIUrl":"https://doi.org/10.1274/JMOR.20.124","url":null,"abstract":"Mouse p ronuc lear em bryos we re cryopreserved by a simple and safe vitrification method. In the process, Vitrification Media VT101, Thawing Media VT 102 (KITAZATO. Co. Japan) and the embryos were loaded into a straw; then they were cryopreserved. Different loading methods were examined to determine the safety levels of crystallization for the embryos survival after thawing. The best condition attained, after thawing, was a 75% embryo survived rate of which 66% developed to the two-cell stage, 71% developed to the morula stage and 27% developed to the blastosyst stage. This development of embryos after vitrification was not significantly different to that of a control group without freezing and thawing. The vitrification method was considered to protect embryos against various infections via liquid nitrogen during cryopreservation. It is expected that the method can be applied to human embryos.","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"45 1","pages":"124-128"},"PeriodicalIF":0.0,"publicationDate":"2003-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89820816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The generation of animals cloned by means of the nuclear transfer technique indicates that somatic cell nuc le i can be rep rogrammed when t hey a re transplanted into the egg cytoplasmin other words, the transplanted somatic nuclei can be induced to return to a pluripotent state similar to that of the nuclei of fert il ized eggs. Therefore, the potential for both reprogramming and pluripotency is retained in germ cells throughout their development. For example, embryonic germ (EG) cells that are generated from primordial germ cells (PGCs) show similar pluripotency to the undifferentiated embryonic stem (ES) cells that originate in the inner cell mass of blastocyst embryos in mice [1 ] . And some te ra tomas tha t genera te differentiated cells of various typesfrom all three pr imary germ layersor ig inate in PGCs in the embryonic gonads [2]. Therefore, germ cells must have the ab i l i t y to be reprogrammed, as we l l as to differentiate to form gametes. So how do germ cells acquire these character ist ics, and how are they maintained during development? The discovery of the molecular and cellular mechanisms that are involved in these processes will provide important insights not only for basic research into reproductive biology but also for the development of new techniques for regenerative medical treatments. There is an urgent need to develop i n v i t r o s ys tems t ha t can mode l t he en t i r e developmental processfrom pluripotent stem cells to func t i ona l spe rm and eggsto f u r t he r ou r understanding of the mechanisms of germ-cel l differentiation.
通过核移植技术克隆的动物表明，当体细胞核被重新移植到卵细胞质中时，体细胞核可以被重新编程，换句话说，移植的体细胞核可以被诱导回到类似于受精卵核的多能状态。因此，生殖细胞在整个发育过程中都保留了重编程和多能性的潜力。例如，由原始生殖细胞(PGCs)产生的胚胎生殖细胞(EG)与起源于小鼠[1]囊胚内细胞群的未分化胚胎干(ES)细胞表现出类似的多能性。还有一些从所有三个初级胚层中产生不同类型分化细胞的肿瘤，或者在胚胎性腺中产生PGCs。因此，生殖细胞必须具有可重新编程的ab - i - 1，因为我们必须分化形成配子。那么，生殖细胞是如何获得这些特性的，又是如何在发育过程中维持这些特性的呢?这些过程中涉及的分子和细胞机制的发现不仅将为生殖生物学的基础研究提供重要见解，而且还将为再生医学治疗的新技术的发展提供重要见解。目前迫切需要开发一种能够模拟多种发育过程(从多能干细胞到功能干细胞，再到生殖细胞和卵子)的新技术，以帮助我们更好地理解生殖细胞分化的机制。
{"title":"Germ Cell Differentiation in Culture","authors":"T. Noce","doi":"10.1274/JMOR.20.69","DOIUrl":"https://doi.org/10.1274/JMOR.20.69","url":null,"abstract":"The generation of animals cloned by means of the nuclear transfer technique indicates that somatic cell nuc le i can be rep rogrammed when t hey a re transplanted into the egg cytoplasmin other words, the transplanted somatic nuclei can be induced to return to a pluripotent state similar to that of the nuclei of fert il ized eggs. Therefore, the potential for both reprogramming and pluripotency is retained in germ cells throughout their development. For example, embryonic germ (EG) cells that are generated from primordial germ cells (PGCs) show similar pluripotency to the undifferentiated embryonic stem (ES) cells that originate in the inner cell mass of blastocyst embryos in mice [1 ] . And some te ra tomas tha t genera te differentiated cells of various typesfrom all three pr imary germ layersor ig inate in PGCs in the embryonic gonads [2]. Therefore, germ cells must have the ab i l i t y to be reprogrammed, as we l l as to differentiate to form gametes. So how do germ cells acquire these character ist ics, and how are they maintained during development? The discovery of the molecular and cellular mechanisms that are involved in these processes will provide important insights not only for basic research into reproductive biology but also for the development of new techniques for regenerative medical treatments. There is an urgent need to develop i n v i t r o s ys tems t ha t can mode l t he en t i r e developmental processfrom pluripotent stem cells to func t i ona l spe rm and eggsto f u r t he r ou r understanding of the mechanisms of germ-cel l differentiation.","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"32 1","pages":"69-73"},"PeriodicalIF":0.0,"publicationDate":"2003-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84226112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently the blastocyst stage transfer (BST) has been applied with several kinds of sequential media and good results have been achieved. The technique made it possible to select embryo potential for implantation and to prevent multiple pregnancies, especially triplets. Several reports [1] have been published on the efficacy of BST. One paper reported an improved pregnancy rate compared with Day 3 transfer and another [2] reported a very high conception rate and statistically better results than Day 2/3 transfer in cases of recurrent failure and aged women [3]. Several studies have described, however, the rate of conception to be app rox ima te l y equa l c ompared t o t ha t o f the conventional method [4, 5]. It would be therefore important to choose cases to apply BST to, such as recurrent unsuccessful or aged cases. Since BST has been developed, most IVF centers have adopted the technique, but there would be more room to improve the clinical results. In the present study, the choice of the medium in BST was discussed. And the efficacy of the two-step embryo transfer method that is one of the techniques developed to apply BST was estimated.
{"title":"Trials for Improvement of Blastocyst Stage Transfer Technique","authors":"Y. Morimoto, Takuji Nishihara","doi":"10.1274/JMOR.20.20","DOIUrl":"https://doi.org/10.1274/JMOR.20.20","url":null,"abstract":"Recently the blastocyst stage transfer (BST) has been applied with several kinds of sequential media and good results have been achieved. The technique made it possible to select embryo potential for implantation and to prevent multiple pregnancies, especially triplets. Several reports [1] have been published on the efficacy of BST. One paper reported an improved pregnancy rate compared with Day 3 transfer and another [2] reported a very high conception rate and statistically better results than Day 2/3 transfer in cases of recurrent failure and aged women [3]. Several studies have described, however, the rate of conception to be app rox ima te l y equa l c ompared t o t ha t o f the conventional method [4, 5]. It would be therefore important to choose cases to apply BST to, such as recurrent unsuccessful or aged cases. Since BST has been developed, most IVF centers have adopted the technique, but there would be more room to improve the clinical results. In the present study, the choice of the medium in BST was discussed. And the efficacy of the two-step embryo transfer method that is one of the techniques developed to apply BST was estimated.","PeriodicalId":90599,"journal":{"name":"Journal of mammalian ova research","volume":"4 1","pages":"20-24"},"PeriodicalIF":0.0,"publicationDate":"2003-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89307541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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