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Results 451 - 500 of 2135
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Newmark Judith A - - 2007
The number of cells in a preimplantation embryo is directly correlated to the health and viability of the embryo. There are currently no methods to count the number of cells in late-stage preimplantation embryos noninvasively. We assessed the ability of optical quadrature microscopy (OQM) to count the number of cells ...
Uchiumi Takao - - 2007
In vitro fertilization (IVF) systems using isolated male and female gametes have been utilized to dissect fertilization-induced events in angiosperms, such as egg activation, zygote development and early embryogenesis, as the female gametophytes of plants are deeply embedded within ovaries. In this study, a rice IVF system was established to ...
Lengerke Claudia - - 2007
Embryonic stem cells (ESCs) hold unique promise for the development of cell replacement therapies, but derivation of therapeutic products from ESCs is hampered by immunological barriers. Creation of HLA-typed ESC banks, or derivation of customized ESC lines by somatic cell nuclear transfer, have been envisioned for engineering histocompatible ESC-derived products. ...
Hua Song - - 2008
The objective of the study was to investigate interspecies somatic cell nuclear transfer (iSCNT) embryonic potential and mitochondrial DNA (mtDNA) segregation during preimplantation development. We generated bovine-ovine reconstructed embryos via iSCNT using bovine oocytes as recipient cytoplasm and ovine fetal fibroblast as donor cells. Chromosome composition, the total cell number ...
Fu Wenqing - - 2007
A novel possible approach to the derivation of human embryonic stem (ES) cell's analogues, named tetraploid meiosis (TM) cells, derived from a prospective patient's or a senior's (PS) somatic cells is described. In this procedure, most of the resulting cells' mitochondrial DNA, if not all, is also from the PS's ...
Elliott Thomas A - - 2007
OBJECTIVE: To develop a mouse model to investigate the possible causes for increased success rates when lysed cells are removed from thawed embryos. DESIGN: Experimental study. SETTING: Clinical IVF laboratory. INTERVENTION(S): Assisted hatching, cell lysis, and removal of lysed cells. MAIN OUTCOME MEASURE(S): Embryonic growth rate and morphology. RESULT(S): The ...
Ito Yoshihiro - - 2007
In current and past practice, murine or primate embryonic stem (ES) cells are usually cultured on live nurse cells for growth that keeps the cells in an undifferentiated state. It is troublesome, however, to prepare nurse cells for each cell culture and it is difficult to completely remove the nurse ...
Talbot Neil C - - 2007
Two porcine cell lines of yolk-sac visceral endoderm, designated as PE-1 and PE-2, were derived from in vivo 11-d porcine blastocysts that were either ovoid (PE-1) or at the early tubular stage of elongation (PE-2). Primary and secondary culture of the cell lines was done on STO feeder cells. The ...
Chen N - - 2007
Somatic cell nuclear transfer (SCNT) is not successful so far in non-human primates. The objective of this study was to investigate the effects of stimulation cycles (first and repeat) on oocyte retrieval and in vitro maturation (IVM) and to evaluate the effects of stimulation cycles and donor cell type (cumulus ...
Chan Wen-hsiung - - 2007
AIM: To examine the cytotoxic effects of genistein, an isoflavone compound, on early postimplantation embryonic development in vitro. METHODS: Mouse blastocysts were incubated in medium with or without genistein (25 or 50 micromol/L) or daidzein (50 micromol/L) for 24 h. Cell proliferation and growth was investigated by dual differential staining, ...
Okahara-Narita Junko - - 2007
In nonhuman primates (NHPs), there have so far been few reports about nuclear transfer (NT), especially using adult somatic cells. The objective of this study was to determine the developmental competence of NT embryos derived from various somatic cells embryonic stem (ES), amniotic epithelial, cumulus, or fetal fibroblast cells] and ...
Torres-Padilla Maria-Elena ME The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, - - 2007
It has been generally accepted that the mammalian embryo starts its development with all cells identical, and only when inside and outside cells form do differences between cells first emerge. However, recent findings show that cells in the mouse embryo can differ in their developmental fate and potency as early ...
Foster Helen A - - 2007
Gametogenesis and embryogenesis are dynamic developmental stages marked by extensive modifications in the organization of the genome and nuclear architecture. In the literature it is conveyed that only B-type lamins are required in these early stages of development and that A-type lamins are not present or required until differentiation of ...
Sun Hong - - 2007
A balance between proliferation and apoptosis is crucial for cellular homeostasis, and its disruption leading to enhanced cellular proliferation and uncontrolled growth are hallmarks of cancer. Genetic manipulation in the mouse offers a powerful approach to delineate the roles of genes in carcinogenesis and determine the molecular and cellular basis ...
Jenik Pablo D - - 2007
Early embryonic development in the flowering plant Arabidopsis thaliana follows a predictable sequence of cell divisions. Anatomical hallmarks and the expression of marker genes in dynamic patterns indicate that new cell fates are established with virtually every round of mitosis. Although some of the factors regulating these early patterning events ...
Klimanskaya Irina - - 2007
This protocol details a method to derive human embryonic stem (hES) cells from single blastomeres. Blastomeres are removed from morula (eight-cell)-stage embryos and cultured until they form multicell aggregates. These blastomere-derived cell aggregates are plated into microdrops seeded with mitotically inactivated feeder cells, and then connected with neighboring microdrops seeded ...
Laurincik Jozef - - 2007
Transcription of the ribosomal RNA (rRNA) genes occurs in the nucleolus and results in ribosome biogenesis. The rRNA gene activation and the associated nucleolus formation may be used as a marker for the activation of the embryonic genome in mammalian embryos and, thus serve to evaluate the developmental potential of ...
Piliszek Anna - - 2007
Foetal fibroblasts (FFs) labelled with vital fluorescent dye were microsurgically introduced into eight-cell mouse embryos, three cells to each embryo. FFs were first identified in the inner cell mass (ICM) in about one-third of embryos, whereas in three quarters of embryos FFs were located among trophoblast cells. Some elimination of ...
Ferreira Christina Ramires - - 2007
The mechanisms controlling the outcome of donor cell-derived mitochondrial DNA (mtDNA) in cloned animals remain largely unknown. This research was designed to investigate the kinetics of somatic and embryonic mtDNA in reconstructed bovine embryos during preimplantation development, as well as in cloned animals. The experiment involved two different procedures of ...
Strange Kevin - - 2007
Cell culture is an invaluable tool for investigation of basic biological processes. However, technical hurdles including low cell yield, poor cell differentiation and poor attachment to the growth substrate have limited the use of this tool for studies of the genetic model organism Caenorhabditis elegans. This protocol describes a method ...
Chen Da-Yuan - - 2007
Our and other previous studies have shown that telophase enucleation is an efficient method for preparing recipient cytoplasts in nuclear transfer. Conventional methods of somatic cell nuclear transfer either by electro-fusion or direct nucleus injection have very low efficiency in animal somatic cell cloning. To simplify the manipulation procedure and ...
Fulka Josef J - - 2007
It is now more than nine years since Dolly, the world's first somatic cell cloned mammal was born, and the success of somatic cell nuclear transfer (SCNT) is still disappointingly low. Only about 3-5% of reconstructed embryos develop to term, and it is also evident that even if some clones ...
Du Yutao - - 2007
Successful cryopreservation of porcine embryos offers a promising perspective in the fields of agriculture, animal science, and human medical research. The objective of the present work was to establish a system facilitating the cryopreservation of porcine embryos produced by somatic cell nuclear transfer (SCNT). Several key techniques including micromanipulator-based enucleation, ...
Merico Valeria - - 2007
Chromosomes, sub-chromosomal regions and genes are repositioned during cell differentiation to acquire a cell-type-specific spatial organization. The constraints that are responsible for this cell-type-specific spatial genome positioning are unknown. In this study we addressed the question of whether epigenetic genome modifications may represent constraints to the acquisition of a specific ...
Zhang Yunhai - - 2007
The present study was designed to examine the effect of trichostatin A (TSA), an inhibitor of histone deacetylase, on development of porcine cloned embryos. Our results showed that treatment of cloned embryos derived from sow oocytes with 50 nM TSA for up to 24 h after the onset of activation ...
Andrews Robert - - 2007
BACKGROUND: Endocytosis is involved in the regulation of many cellular events, including signalling, cell migration, and cell polarity. To begin to investigate roles for endocytosis in early C. elegans development, we examined the distribution and dynamics of early endosomes (EEs) in embryos. METHODOLOGY/PRINCIPAL FINDINGS: EEs are primarily found at the ...
Yoo Jae Gyu - - 2007
Many factors influence success rates in animal cloning by somatic cell nuclear transfer (SCNT), including cell cycle stage of donor cells and recipient oocytes, the procedure of micromanipulation, and the activation protocol. This study was conducted to determine the effects of cell cycle coordination for cloning rats from fetal fibroblasts ...
Vemuri Mohan C - - 2007
Human embryonic stem cells (hESC) have the potential to treat a wide range of diseases. Currently, the use of existing hESC lines in human clinical applications is limited, as they are derived from blastocysts subjected to immunosurgery with animal derived antibodies, and are maintained on mouse embryonic feeder (MEF) cells, ...
Torre Maria L - - 2007
Cell encapsulation is an evolving branch of biotechnology with numerous applications including the enhancing of reproductive performance both in humans and other mammal species. Over the last twenty years male and female gametes and embryos have been encapsulated with or without somatic cells, for different purposes, such as semen controlled ...
Bjerregaard Bolette - - 2007
The onset of ribosomal RNA (rRNA) synthesis occurs during the second half of the third cell cycle, that is, at the four-cell stage, in porcine embryos developed in vivo. In the present study the onset of rRNA synthesis was investigated in porcine embryos produced in vitro (IVP) or by somatic ...
Malcuit Christopher - - 2007
In all animal species, initiation of embryonic development occurs shortly after the joining together of the gametes from each of the sexes. The first of these steps, referred to as "egg activation", is a series of molecular events that results in the syngamy of the two haploid genomes and the ...
Khaner Oded - - 2007
The avian blastoderm acts during its early stages of development as an integrative system programmed to form a single embryonic axis. Here, I report the results of a variety of transplantation experiments of the midline region at stages X-XII, which were carried out to study their relevance for axis initiation. ...
Fahrudin Mokhamad - - 2007
The present study was designated to examine the possibility of producing somatic cell nuclear transfer (SCNT) embryos in pigs using oocyte cytoplasm fragments (OCFs), prepared by centrifugations, as recipient cytoplasts. In Experiment 1, in vitro matured oocytes were centrifuged at 13,000 x g for 3, 6, and 9 min to ...
Tani Tetsuya - - 2007
Despite the long-held assumption that reprogramming factors are present in mammalian oocytes at the second metaphase stage, the molecular nature of these factors is not known. Here, we demonstrated that oocytes with the potential to reprogram somatic cell nuclei have a unique 23-kDa protein, phosphorylated transcriptionally controlled tumor protein (TCTP). ...
Perea-Gomez Aitana A Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, UK. - - 2007
Reciprocal interactions between two extra-embryonic tissues, the extra-embryonic ectoderm and the visceral endoderm, and the pluripotent epiblast, are required for the establishment of anterior-posterior polarity in the mouse. After implantation, two visceral endoderm cell types can be distinguished, in the embryonic and extra-embryonic regions of the egg cylinder. In the ...
Hue I I INRA, UMR 1198, ENVA, CNRS, FRE 2857, Biologie du Développement et Reproduction, Jouy en Josas F-78350, France. - - 2007
In ruminants, more than 30% of the embryonic losses observed after artificial insemination (AI) have an early origin, coincident with a marked elongation of the trophoblast which occurs before implantation. Several observations provide clear evidence that early elongation of the conceptus relies on cell multiplication, cell growth and cell shape ...
Roszko Isabelle - - 2007
The antero-posterior dispersion of clonally related cells is a prominent feature of axis elongation in vertebrate embryos. Two major models have been proposed: (i) the intercalation of cells by convergent-extension and (ii) the sequential production of the forming axis by stem cells. The relative importance of both of these cell ...
Nakamoto, Ayaki
In embryos of the oligochaete annelid Tubifex, most ectodermal tissues are derived from four bilateral pairs of embryonic stem cells called teloblasts (ectoteloblasts N, O, P and Q). Ectoteloblasts are generated on both left and right sides of the embryo through an invariable sequence of cell divisions of a proteloblast, ...
Wakayama Sayaka - - 2007
Recently, ES cell lines were established from single blastomeres taken from eight-cell embryos in mice and humans with success rates of 4% and 2%, respectively, which suggests that the method could be used in regenerative medicine to reduce ethical concerns over harm to embryos. However, those studies used other ES ...
Minasaki Ryuji - - 2007
In the early Caenorhabditis elegans embryo, a rapid succession of cell divisions, many of them asymmetric, form blastomeres that differ in size, cell cycle duration and developmental potential. These early cell cycles are highly regulated and controlled by maternally contributed products. We describe here a novel gene, mel-47, that is ...
Jang G - - 2007
Since the only viable cloned offspring born in dogs was a male, the purpose of the present study was to produce female puppies by somatic cell nuclear transfer (SCNT). Adult ear fibroblasts from a 2-month-old female Afghan hound were isolated and used as donor cells. In vivo-matured canine oocytes surgically ...
Cohen Jacques - - 2007
OBJECTIVE: To evaluate whether differences in results between studies that involve preimplantation genetic diagnosis for chromosome testing are affected by technology, such as the number of cells to be biopsied or by differences in study design. DESIGN: Evaluation of studies of aneuploidy testing according to the use of probes, fixation ...
Mizutani Eiji - - 2006
The success rate is generally higher when cloning mice from embryonic stem (ES) cell nuclei than from somatic cell nuclei, suggesting that the embryonic nature or the undifferentiated state of the donor cell increases cloning efficiency. We assessed the developmental ability of cloned embryos derived from cultured neural stem cell ...
Miyamoto Kei - - 2007
The relationship between donor cell cycle and the developmental ability of somatic cell nuclear transfer (SCNT) embryos has not fully been elucidated. Donor cells that are usually prepared by serum starvation or confluent-cell culture for SCNT represent a heterogeneous population that includes mainly G0 phase cells, other cells in different ...
Leibo S P - - 2007
Increasingly innovative and imaginative techniques are being developed to investigate the development of animal and human embryos. Among the types of techniques that have been developed are ones that deal with oocyte maturation and culture, the isolation and utilization of stem cells, cryopreservation of reproductive cells and tissues, and various ...
Yin Xi-Jun - - 2007
In the present study, we compared in vitro and in vivo development of nuclear transfer (NT) embryos derived from serum-starved or non-serum-starved odd-eyed cat skin fibroblast cells. Flow cytometry analyses revealed that a higher percentage of cells were in the G0/G1 phase after serum starvation (89.3%) as compared with non-serum-starved ...
Belmonte Mark F - - 2007
In white spruce (Picea glauca), an improvement of somatic embryo yield and quality can be achieved by applications of DL: -buthionine-[S,R]-sulfoximine (BSO), which inhibits the biosynthesis of reduced glutathione (GSH), thereby switching the total glutathione pool towards its oxidized form (GSSG). Applications of BSO almost tripled the embryogenic output of ...
Liu Chao-Lien - - 2007
l(2)dtl (lethal (2) denticleless), is an embryonic lethal homozygous mutation initially identified in Drosophila melanogaster that produces embryos that lack ventral denticle belts. In addition to nucleotide sequence, bioinformatic analysis has revealed a conservation of critical functional motifs among the human L2DTL, mouse L2dtl, and Drosophila l(2)dtl proteins. The function ...
Castro-Rendón W A - - 2006
The successful implantation of the blastocyst depends on adequate interactions between the embryo and the uterus. The development of the embryo begins with the fertilized ovum, a single totipotent cell which undergoes mitosis and gives rise to a multicellular structure named blastocyst. At the same time, increasing concentrations of ovarian ...
Hara Kentaro - - 2006
Replication of DNA is strictly controlled to ensure that it occurs only once per cell cycle. Geminin has been thought to serve as a central mediator of this licensing mechanism by binding to and antagonizing the function of Cdt1 and thereby preventing re-replication during S and G2 phases. We have ...
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