| 单词 | oocyte |
| 例句 | “If you would like WIH to continue to store your embryos/oocytes,” the letter said, “please return a copy of this letter, signed and notarized, along with a check in the amount of $500.” The Lost Embryos 2021-04-16T04:00:00Z After six days, the females’ oocytes were measured again, to see how much they’d grown since the beginning of the experiment. A loving touch triggers cockroaches to make babies faster 2014-04-05T12:00:00Z The language at the fertility clinic I contacted was very specific: It is illegal for oocyte donors to sell their eggs. Selling my eggs to make rent 2013-02-03T18:00:00Z Cape buffalos are notoriously bad-tempered and dangerous animals and Vasti was sedated when her oocytes, or egg cells, were extracted using a technique similar to that used on human donors. South Africa unveils test-tube buffalo, plans IVF rhino 2016-09-23T04:00:00Z The developing eggs known as oocytes, by contrast, draw energy primarily from surrounding cells, not from their own mitochondria, so maintain relatively pristine mtDNA. Mature sperm lack intact mitochondrial DNA 2023-09-18T04:00:00Z Spermatozoa carried along by water currents can fertilize the oocytes borne in the mesohyl of other sponges. Fundamentals of Biology 2015-01-01T00:00:00Z Cell division is again arrested, this time at metaphase II. At ovulation, this secondary oocyte is released and travels toward the uterus through the oviduct. Concepts of Biology 2013-04-25T00:00:00Z In the ovary, the manipulated cell developed into an egg cell, or oocyte. Mice with Two Fathers? Researchers Develop Egg Cells from Male Mice 2023-03-15T04:00:00Z If they infect sperm cells or oocytes, the precursors of eggs, their genes become part of our DNA and can be passed on to our offspring. Ancient virus may be protecting the human placenta 2022-10-27T04:00:00Z The cell starting meiosis is called a primary oocyte, as shown in Figure 34.15. Biology for AP Courses 2022-06-09T00:00:00Z A secondary oocyte must be fertilized by the male gamete before it becomes an “ovum” or “egg.” Fundamentals of Biology 2015-01-01T00:00:00Z This results in a primary oocyte finishing the first meiotic division. Concepts of Biology 2013-04-25T00:00:00Z “It’s a huge achievement, but it’s still an indication that there are problems with these in vitro–derived oocytes from the stem cells, so there’s a lot of work that has to be done.” Mice with Two Fathers? Researchers Develop Egg Cells from Male Mice 2023-03-15T04:00:00Z Sperm must undergo the process of capacitation in order to have the “capacity” to fertilize an oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z This results in the primary oocyte finishing the first meiotic division. Biology for AP Courses 2022-06-09T00:00:00Z While both the female and male reproductive systems are involved with producing, nourishing and transporting either the oocyte or sperm, they are different in shape and structure. Fundamentals of Biology 2015-01-01T00:00:00Z Normally, oocytes progress more rapidly through early meiosis than do spermatocytes. How sex chromosomes break up to get together 2020-05-26T04:00:00Z "We brought 10 oocytes back from Kenya, five from each female. After incubation, seven matured and were suitable for fertilization," Galli said. Scientists create northern white rhino embryos in milestone that could save the species from extinction 2019-09-11T04:00:00Z To reach the oocyte itself, the sperm must penetrate the two protective layers. Anatomy and Physiology 2013-06-19T00:00:00Z At ovulation, this secondary oocyte will be released and travel toward the uterus through the oviduct. Biology for AP Courses 2022-06-09T00:00:00Z This means she is born with a predetermined number of oocytes and cannot produce new ones. Fundamentals of Biology 2015-01-01T00:00:00Z To test this, they investigated chromosome structure and break frequency in the meiotic precursors of eggs, oocytes. How sex chromosomes break up to get together 2020-05-26T04:00:00Z "Because we are injecting unfertilized eggs, we thought that we would only be able to perform gene editing on the alleles inherited from the mother. Paternal DNA isn't in these unfertilized oocytes," Menke said. The first gene-edited lizard walks among us 2019-09-04T04:00:00Z These enzymes clear a path through the zona pellucida that allows sperm to reach the oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z Figure 34.28 In humans, fertilization occurs soon after the oocyte leaves the ovary. Biology for AP Courses 2022-06-09T00:00:00Z The oogonia produce primary oocytes that are arrested in prophase I of meiosis from the time of birth until puberty. Fundamentals of Biology 2015-01-01T00:00:00Z "Now the injected oocytes are incubated and we need to wait to see if any viable embryo develop to the stage where it can be cryopreserved for later transfer." Northern white rhino eggs successfully fertilized 2019-08-26T04:00:00Z While the percentage of oocytes yielding gene-edited offspring was low compared to other species, these results are a successful start. The first gene-edited lizard walks among us 2019-09-04T04:00:00Z As you can see, the first sperm to reach the oocyte is never the one to fertilize it. Anatomy and Physiology 2013-06-19T00:00:00Z Explain the fate of the newly released secondary oocyte after ovulation. Biology for AP Courses 2022-06-09T00:00:00Z This results in the production of a secondary oocyte and one polar body. Fundamentals of Biology 2015-01-01T00:00:00Z However, there were varying levels of DNA damage done, which the researchers said "were comparable to those of frozen-thawed mouse sperm and were reduced in some reconstructed oocytes." Woolly mammoth cells brought back to life in shocking scientific achievement 2019-03-12T04:00:00Z Unexpectedly, many others reside in distal regions that overlap with DNA hypomethylated domains in human oocytes and are enriched for transcription factor-binding sites. Chromatin analysis in human early development reveals epigenetic transition during ZGA 2018-05-01T04:00:00Z The answer lies, of course, in the DNA in the sperm and oocyte that combined to produce that first diploid cell, the human zygote. Anatomy and Physiology 2013-06-19T00:00:00Z Which process results in the formation of the secondary oocyte? Biology for AP Courses 2022-06-09T00:00:00Z Data from Xenopus oocytes indicate that this mechanism may be conserved in vertebrates. A lysosomal switch triggers proteostasis renewal in the immortal C. elegans germ lineage 2017-11-21T05:00:00Z They took a close look at the proteins in the worm’s egg-like cells, called oocytes. Young Again: How One Cell Turns Back Time 2017-11-22T05:00:00Z Right, the human oocyte, blastocyst, sperm and ES cell DNA methylation levels around these promoters are also shown. Chromatin analysis in human early development reveals epigenetic transition during ZGA 2018-05-01T04:00:00Z This occurs when the sperm and oocyte combine at the moment of your conception. Anatomy and Physiology 2013-06-19T00:00:00Z A diploid oogonium forms a haploid oocyte by the process of mitosis. Biology for AP Courses 2022-06-09T00:00:00Z A sperm cytoskeletal protein that signals oocyte meiotic maturation and ovulation. A lysosomal switch triggers proteostasis renewal in the immortal C. elegans germ lineage 2017-11-21T05:00:00Z In our studies with human oocytes and zygotes, we used purified recombinant Cas9 protein instead of plasmid, which may enhance the specificity while shortening enzymatic exposure time, thereby diminishing off-site targeting. Correction of a pathogenic gene mutation in human embryos : Nature : Nature Research 2017-08-01T04:00:00Z The oocytes were injected at the metaphase II stage of their cell cycle. Biotechnology: At the heart of gene edits in human embryos : Nature : Nature Research 2017-08-01T04:00:00Z When the first sperm fuses with the oocyte, the oocyte deploys two mechanisms to prevent polyspermy, which is penetration by more than one sperm. Anatomy and Physiology 2013-06-19T00:00:00Z A haploid oogonium forms a diploid oocyte by the process of meiosis. Biology for AP Courses 2022-06-09T00:00:00Z The Darwin Life website says that HER IVF is “designed to reverse the effects of age on human oocytes and repair certain cellular defects.” The 'three-parent baby' fertility doctor needs to stop marketing the procedure, FDA says 2017-08-05T04:00:00Z Number of oocytes/embryos/blastocysts shown in bars; percentage shown above bars. Correction of a pathogenic gene mutation in human embryos : Nature : Nature Research 2017-08-01T04:00:00Z Dunja Baston-Büst at Germany's University Hospital Düsseldorf, for instance, agrees that spermbots might be useful for delivering drugs or genes into the female reproductive tract to treat cancers or diseases of the oocyte. Medical microbots need better imaging and control 2017-05-23T04:00:00Z This is critical because if more than one sperm were to fertilize the oocyte, the resulting zygote would be a triploid organism with three sets of chromosomes. Anatomy and Physiology 2013-06-19T00:00:00Z A diploid oogonium forms a haploid oocyte by the process of meiosis. Biology for AP Courses 2022-06-09T00:00:00Z “It is too preliminary to use artificial oocytes in the clinic,” he says, cautioning that his study showed that the artificial mouse eggs were often of low quality. Mouse eggs made from skin cells in a dish 2016-10-16T04:00:00Z We next evaluated targeting outcomes in human zygotes produced by fertilizing healthy donor oocytes with sperm from the patient heterozygous for the MYBPC3 mutation. Correction of a pathogenic gene mutation in human embryos : Nature : Nature Research 2017-08-01T04:00:00Z “The mouse supporting cells don’t work for the human oocytes. We need human supporting cells.” Japanese Scientists Master Egg Creation Process in Mice 2016-10-17T04:00:00Z Only upon fertilization does the oocyte complete meiosis. Anatomy and Physiology 2013-06-19T00:00:00Z A haploid oogonium forms a haploid haploid oocyte by the process of meiosis. Biology for AP Courses 2022-06-09T00:00:00Z In 2013, the American Society of Reproductive Medicine revised its ethics committee report on oocyte or embryo donation to women of “advanced” age. Single, 54, and a New Dad: Why Some Start Families Late 2016-08-05T04:00:00Z Number of oocytes/embryos/blastocysts shown in bars; percentage shown above bars. Correction of a pathogenic gene mutation in human embryos : Nature : Nature Research 2017-08-01T04:00:00Z The new technique will allow researchers to better understand how eggs mature by directly observing complex signaling between an oocyte and the surrounding cells that direct its development. Mouse eggs grown in lab dish 2016-07-25T04:00:00Z At this moment, the oocyte has become an ovum, the female haploid gamete. Anatomy and Physiology 2013-06-19T00:00:00Z Walker: Bill used to keep the embryos and oocytes — when he was bringing them back up from the farm — in his top shirt pocket. Dolly at 20: The inside story on the world’s most famous sheep 2016-06-28T04:00:00Z Sister germ cells provide organelles and cytoplasm to oocytes to augment their developmental potential. Mouse oocytes differentiate through organelle enrichment from sister cyst germ cells | Science 2016-03-31T04:00:00Z Immediately following oocyte retrieval, recovered gametes were transferred to the research laboratory. Correction of a pathogenic gene mutation in human embryos : Nature : Nature Research 2017-08-01T04:00:00Z There are the reproductive biologists appalled by the company’s activities, who say evidence is overwhelming that oocyte stem cells do not exist in adult mammals. Feature: A controversial company offers a new way to make a baby 2015-11-05T05:00:00Z The number of sperm that reach the oocyte is greatly reduced because of conditions within the female reproductive tract. Anatomy and Physiology 2013-06-19T00:00:00Z Ritchie: The simple way of describing nuclear transfer is that you take an oocyte, an unfertilized egg, and you remove the chromosomes. Dolly at 20: The inside story on the world’s most famous sheep 2016-06-28T04:00:00Z Sister germ cells provide organelles and cytoplasm to oocytes to augment their developmental potential. Mouse oocytes differentiate through organelle enrichment from sister cyst germ cells | Science 2016-03-31T04:00:00Z For women with cancer who opt for cryopreservation, one issue is whether to freeze and store unfertilized eggs, called oocytes, or fertilized eggs – embryos created with their partner. Preparing for a Baby After Cancer 2015-06-19T04:00:00Z “They got the mice,” says Evelyn Telfer, a reproductive biologist at the University of Edinburgh, who has visited Wu’s lab and thinks oocyte stem cells likely exist. Feature: A controversial company offers a new way to make a baby 2015-11-05T05:00:00Z One of the sperm will then break through to the oocyte’s plasma membrane and release its haploid nucleus into the oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z The last thing you want to do is waste those oocytes you've got. Dolly at 20: The inside story on the world’s most famous sheep 2016-06-28T04:00:00Z The oocytes sit on devices that look like coffee stirrers in liquid nitrogen tanks. ‘Lean in. But freeze first.’ The fertility business targets women’s fears. 2015-03-06T05:00:00Z Once the somatic cell nucleus is in place, a lab worker uses electricity to fuse the nucleus and oocyte together into a reconstructed embryo that’s implanted into a surrogate mother. For $100,000, You Can Clone Your Dog 2014-10-22T04:00:00Z At least four groups tried and failed to find oocyte stem cells that turn into mature eggs. Feature: A controversial company offers a new way to make a baby 2015-11-05T05:00:00Z The gamete they produce is called an oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z Higher levels of BPA were linked to stunted human oocytes, as well as indications of chromosomal damage – a finding also found in animals studied by Dr. Hunt. In Plastics and Cans, a Threat to Women 2014-08-28T04:00:00Z A long, long time ago a virus infected a sperm cell or oocyte of one of our ancestors. Genetic Chimeras: Are You Your Own Twin? 2014-04-13T09:41:16Z We favour this last possibility because it agrees with the known importance of cytoplasmic polyadenylation for activating genes in maturing oocytes and early embryos of Xenopus and in certain other vertebrate contexts. Poly(A)-tail profiling reveals an embryonic switch in translational control 2014-04-04T22:51:04.645Z As for Tilly, now at Northeastern University in Boston, he’s pressing ahead with studies of putative oocyte stem cells, including how they behave naturally in the body. Feature: A controversial company offers a new way to make a baby 2015-11-05T05:00:00Z This grouping of an oocyte and its supporting cells is called a follicle. Anatomy and Physiology 2013-06-19T00:00:00Z “Together with prior animal studies, the data support the negative influences of BPA on oocyte maturation,” the Harvard team concluded. In Plastics and Cans, a Threat to Women 2014-08-28T04:00:00Z The sperm or oocyte was fertilized and became a fetus, and that fetus now carried the bit of viral DNA. Genetic Chimeras: Are You Your Own Twin? 2014-04-13T09:41:16Z At a two-day hearing starting today the FDA advisory committee will broadly discuss the state of oocyte modification science and what clinical trials should look like for procedures designed to modify human eggs. Making Babies with 3 Genetic Parents Gets FDA Hearing 2014-02-25T12:00:00Z The company is poised to introduce a second treatment using these cells, often called oocyte stem cells, to directly restore fertility. Feature: A controversial company offers a new way to make a baby 2015-11-05T05:00:00Z The initiation of ovulation—the release of an oocyte from the ovary—marks the transition from puberty into reproductive maturity for women. Anatomy and Physiology 2013-06-19T00:00:00Z Noting that BPA also turned up in follicular fluid, the investigators also looked at 357 discarded oocytes from more than 120 women visiting the clinics. In Plastics and Cans, a Threat to Women 2014-08-28T04:00:00Z Checkpoint mechanisms of hitherto unknown nature eliminate oocytes with unrepaired DNA damage, causing recombination-defective mutant mice to be sterile. [Report] Reversal of Female Infertility by Chk2 Ablation Reveals the Oocyte DNA Damage Checkpoint Pathway 2014-01-30T19:26:12.333Z Specific oocyte genes are essential for follicle maintenance and female fertility. [Report] CRL4 Complex Regulates Mammalian Oocyte Survival and Reprogramming by Activation of TET Proteins 2013-12-19T21:56:50.031Z Writing in Nature Genetics, they showed that certain cells could differentiate into something that looked very much like an oocyte under a microscope and responded similarly to hormones. Feature: A controversial company offers a new way to make a baby 2015-11-05T05:00:00Z Just prior to ovulation, a surge of luteinizing hormone triggers the resumption of meiosis in a primary oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z And should donors of human oocytes—necessary for the cloning procedure—be paid for their donations, or does that open the door to exploitation? Live Chat: Is Human Cloning on the Horizon? 2013-06-26T16:10:54Z Exogenous DNA damage is also lethal to oocytes via a highly sensitive checkpoint. [Report] Reversal of Female Infertility by Chk2 Ablation Reveals the Oocyte DNA Damage Checkpoint Pathway 2014-01-30T19:26:12.333Z CRL4 binds to and activates an adaptor protein that mediates ubiquitination, but if any component is deleted, the genes required for oocyte maintenance and early embryo development are silenced and the female mice become infertile. [Report] CRL4 Complex Regulates Mammalian Oocyte Survival and Reprogramming by Activation of TET Proteins 2013-12-19T21:56:50.031Z But these cells didn’t enter meiosis, meaning they were, in Eppig’s words, “oocyte wannabes” and not the real thing. Feature: A controversial company offers a new way to make a baby 2015-11-05T05:00:00Z This initiates the transition from primary to secondary oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z Given the difficulty of obtaining human oocytes, and the controversial nature of the research, embryonic stem cells aren’t likely to ever be the preferred tool of regenerative medicine, he said. Oregon scientists get stem cells from cloned human embryos 2013-05-16T02:12:00Z These data implicate DNA DSB repair efficiency as an important determinant of oocyte aging in women. [Research Articles] Impairment of BRCA1-Related DNA Double-Strand Break Repair Leads to Ovarian Aging in Mice and Humans 2013-02-13T19:25:08.767Z The duration of a woman’s reproductive period is determined by the size and persistence of a dormant oocyte pool. [Report] CRL4 Complex Regulates Mammalian Oocyte Survival and Reprogramming by Activation of TET Proteins 2013-12-19T21:56:50.031Z Given the evidence to date, Clarke seems bewildered that oocyte stem cells are not only hanging on but enhancing their public profile. Feature: A controversial company offers a new way to make a baby 2015-11-05T05:00:00Z The nearby uterine tube, either left or right, receives the oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z The failure of human oocytes to produce them had led some scientists to speculate that the technique simply might not work in people for some reason. Oregon scientists get stem cells from cloned human embryos 2013-05-16T02:12:00Z If the mice were losing oocytes at this rate, their eggs should be depleted far sooner than they actually were. Reproductive biology: Fertile mind 2012-11-14T18:21:14.237Z And while those studies suggest that the technique results in successful pregnancy in young women at the same rate as assisted with “fresh” oocytes, observational studies suggest the success rate is lower. Egg Freezing Enters Clinical Mainstream 2012-10-28T20:20:49.397Z “It looks like human oocytes are more sensitive,” he says. DNA-Swap Technology Almost Ready for Fertility Clinic 2012-10-28T20:18:24.533Z Unlike sperm, oocytes lack flagella, and therefore cannot move on their own. Anatomy and Physiology 2013-06-19T00:00:00Z In one experiment, eight oocytes harvested from one woman produced five blastocysts and four embryonic stem cell lines — a success rate virtually unseen in other animals. Oregon scientists get stem cells from cloned human embryos 2013-05-16T02:12:00Z When her team transplanted the cells into chemotherapy-treated female mice, they developed into mature oocytes, then fertilizable eggs and, the clincher, healthy pups. Reproductive biology: Fertile mind 2012-11-14T18:21:14.237Z Researchers use a micropipette to remove the nuclear DNA from a human oocyte. Exchange of DNA Between Egg Cells May Help Prevent Mitochondrial Diseases 2012-10-24T22:01:56Z The origin of the cytoplasmic condition that induces DNA synthesis has been investigated by injecting adult brain nuclei, together with a radioactive labeling substance, into growing and maturing oocytes. Transplanted Nuclei and Cell Differentiation, by Sir John B. Gurdon 2012-10-09T23:45:00.177Z As a result of these mechanisms, the oocyte–granulosa cell complex is pulled into the interior of the tube. Anatomy and Physiology 2013-06-19T00:00:00Z “Where the kudos come is in being able to over time enhance and improve the technology developed in other species to make this amenable to the human oocyte,” Gearhart said. Oregon scientists get stem cells from cloned human embryos 2013-05-16T02:12:00Z Eventually, his team retrieved cells but “found consistent oocyte contamination”. Reproductive biology: Fertile mind 2012-11-14T18:21:14.237Z Saitou says that with a bit more progress in understanding the complex interactions at work, they may be able to coax the cells through the entire oocyte development process in a lab dish. Sperm and Eggs Created in Dish Produce Mouse Pups 2012-10-04T19:10:00Z The inducing factor appears just after an increase in the level of pituitary hormone has caused an oocyte to mature into an egg, an event that is accompanied by intensive RNA and protein synthesis. Transplanted Nuclei and Cell Differentiation, by Sir John B. Gurdon 2012-10-09T23:45:00.177Z Once inside, the muscular contractions and beating cilia move the oocyte slowly toward the uterus. Anatomy and Physiology 2013-06-19T00:00:00Z Aging of endometrium and oocytes: observations on conception and abortion rates in an egg donation model. SciAm Beginnings: When a Beginning is Not a Beginning 2012-07-31T14:45:03.343Z Tilly says that although mature oocytes do not express vasa on their surface, his cells — which are a cross between embryonic precursors and full-blown oocytes — do. Reproductive biology: Fertile mind 2012-11-14T18:21:14.237Z Although some of the cells might have looked like oocytes, they didn't seem to have the genetic programming to divide in the way he would expect egg stem cells to divide. Stem Cell Study Scrambles Egg Debate, Again 2012-07-10T20:42:35Z Woodland, however, has injected growing oocytes with 10 times the amount of all four common DNA precursors believed to be present in the mature egg. Transplanted Nuclei and Cell Differentiation, by Sir John B. Gurdon 2012-10-09T23:45:00.177Z If the oocyte is successfully fertilized, the resulting zygote will begin to divide into two cells, then four, and so on, as it makes its way through the uterine tube and into the uterus. Anatomy and Physiology 2013-06-19T00:00:00Z Starting at puberty, those oocytes mature at a rate of about 1000 per menstrual cycle. Stem Cells That May Make Eggs Found in Women 2012-02-26T18:00:00Z He concluded that none of it effectively countered a proposal from the 1870s stating that female mammals stop producing oocytes after birth. Reproductive biology: Fertile mind 2012-11-14T18:21:14.237Z The specific subset of stem cells he studies have been demonstrated to express the Ddx4 marker on their cell surfaces, he says, whereas oocytes express the marker only internally. Stem Cell Study Scrambles Egg Debate, Again 2012-07-10T20:42:35Z This phenomenon was demonstrated in amphibian oocytes, the cells that give rise to mature eggs. Transplanted Nuclei and Cell Differentiation, by Sir John B. Gurdon 2012-10-09T23:45:00.177Z In the ovary, an oocyte surrounded by supporting cells is called a follicle. Anatomy and Physiology 2013-06-19T00:00:00Z And once the oocyte supply runs low, menopause begins. Stem Cells That May Make Eggs Found in Women 2012-02-26T18:00:00Z Tilly argued that the bone marrow either protected existing oocytes or revived oocyte formation, but critics argued that the chemotherapy probably didn’t kill off all the recipient’s oocytes in the first place. Reproductive biology: Fertile mind 2012-11-14T18:21:14.237Z When grown in the laboratory, the cells "spontaneously generated" immature eggs - or oocytes, which looked and acted like oocytes in the body. Women's eggs 'can be increased' 2012-02-26T18:02:03Z When the same nuclei were injected into maturing oocytes, they synthesized neither RNA nor DNA but were rapidly converted into groups of chromosomes on spindles. Transplanted Nuclei and Cell Differentiation, by Sir John B. Gurdon 2012-10-09T23:45:00.177Z This larger cell, the secondary oocyte, eventually leaves the ovary during ovulation. Anatomy and Physiology 2013-06-19T00:00:00Z The OSCs grew quickly in the lab, and under certain conditions they spontaneously formed cells that visually and molecularly resemble oocytes. Stem Cells That May Make Eggs Found in Women 2012-02-26T18:00:00Z The oocytes of both the women and the worms, however, age much more rapidly, effectively ending the ability to reproduce during the second half of life, a relatively unique phenomenon in the animal kingdom. Egg Timer: Separate Biological Clocks Govern Female Fertility and Life Span 2011-12-06T00:15:09.730Z Moreover, the process is too inefficient for therapeutic use — 63 oocytes were required to generate one normal set of embryonic cells. Stem Cell Research Shows Promise 2011-10-06T02:03:22Z When DNA and labeled thymidine are introduced into oocytes, no DNA replication can be detected. Transplanted Nuclei and Cell Differentiation, by Sir John B. Gurdon 2012-10-09T23:45:00.177Z How does the diploid secondary oocyte become an ovum—the haploid female gamete? Anatomy and Physiology 2013-06-19T00:00:00Z This human oocyte expressing green fluorescent protein was derived from oogonial stem cells. Stem Cells That May Make Eggs Found in Women 2012-02-26T18:00:00Z When Murphy compared the genes turned off and on in oocytes and body cells of the same worm, however, she saw that two completely different sets of genes controlled oocyte and body-cell aging in . Egg Timer: Separate Biological Clocks Govern Female Fertility and Life Span 2011-12-06T00:15:09.730Z At first they seemed identical, as hoped, to the embryonic cells made with the oocyte method. Stem Cell Research Shows Promise 2011-10-06T02:03:22Z A pronounced swelling is also observed in nuclei injected into oocytes; the swelling is therefore not directly related to a particular type of nuclear response. Transplanted Nuclei and Cell Differentiation, by Sir John B. Gurdon 2012-10-09T23:45:00.177Z Thus, the ovum can be thought of as a brief, transitional, haploid stage between the diploid oocyte and diploid zygote. Anatomy and Physiology 2013-06-19T00:00:00Z They found that in mice, too many oocytes die during each menstrual cycle to sustain the supply of eggs for the animal's lifetime fertility. Stem Cells That May Make Eggs Found in Women 2012-02-26T18:00:00Z "What drives the decline in oocyte quality in human females is chromosome abnormalities," Hassold says. Egg Timer: Separate Biological Clocks Govern Female Fertility and Life Span 2011-12-06T00:15:09.730Z But the method is highly inefficient and would require tens or hundreds of oocytes for each patient. Stem Cell Research Shows Promise 2011-10-06T02:03:22Z When they removed the egg's nucleus, fused the genome-free oocyte with a skin cell, and triggered cell division, the eggs divided once or twice. An Egg-Citing Recipe for Human Stem Cells 2011-10-05T18:00:00Z As you’ll see next, follicles progress from primordial, to primary, to secondary and tertiary stages prior to ovulation—with the oocyte inside the follicle remaining as a primary oocyte until right before ovulation. Anatomy and Physiology 2013-06-19T00:00:00Z A baby girl, for example, is born with an estimated 400,000 oocytes. Stem Cells That May Make Eggs Found in Women 2012-02-26T18:00:00Z Gene activation was also reversed in the oocytes of TGF-β mutants. Egg Timer: Separate Biological Clocks Govern Female Fertility and Life Span 2011-12-06T00:15:09.730Z The council failed to reach consensus on the creation of so-called cybrids, in which the nucleus of a human cell is inserted into an animal oocyte. German Ethics Council Weighs In On Human-Animal Chimeras 2011-09-27T16:26:29Z Many people fear that such research will prompt demand for human oocytes. An Egg-Citing Recipe for Human Stem Cells 2011-10-05T18:00:00Z Primordial follicles have only a single flat layer of support cells, called granulosa cells, that surround the oocyte, and they can stay in this resting state for years—some until right before menopause. Anatomy and Physiology 2013-06-19T00:00:00Z Finding a human version of the cells Wu isolated is "very exciting," says Evelyn Telfer, who studies oocyte development at the University of Edinburgh in the United Kingdom. Stem Cells That May Make Eggs Found in Women 2012-02-26T18:00:00Z The genes linked to oocyte longevity, however, preserved the integrity of chromosomes and DNA. Egg Timer: Separate Biological Clocks Govern Female Fertility and Life Span 2011-12-06T00:15:09.730Z The study, published on Sunday in the journal Nature Methods, involved inserting monkey genes that block the virus into feline eggs, or oocytes, before they are fertilized. Green-glowing cats are new tool in AIDS research 2011-09-11T17:17:44Z According to clinicaltrials.gov, only a few of the registered trials evaluating oocyte cryopreservation even allow healthy women over the age of 37 into the studies, and none of them is studying older women in particular. Growth of egg freezing blurs 'experimental' label 2011-08-24T17:20:27.023Z The one that does not die will continue to grow and develop until ovulation, when it will expel its secondary oocyte surrounded by several layers of granulosa cells from the ovary. Anatomy and Physiology 2013-06-19T00:00:00Z In women, too, aging brings about a decline in the quality of oocytes, leading to a greater chance of birth defects like Down syndrome. Observatory: Looking to a Worm for Answers on Human Fertility 2010-10-15T19:01:00Z The births were part of a "proof of principle" analysis on whether this method of screening of oocytes, or egg cells, and embryos before transfer in IVF can help to increase birth rates. First babies born in IVF full gene screening study 2010-10-15T13:24:00Z In the 1960s, he conducted laboratory studies of sperm and oocytes — immature eggs — with the British scientist Robert Edwards, who helped create the world’s first test tube baby, born in England in 1978. Profile | Dr. Howard W. Jones Jr.: Pioneer Reflects on Future of Reproductive Medicine 2010-03-22T19:36:00Z This degradation of the wall, combined with pressure from the large, fluid-filled antrum, results in the expulsion of the oocyte surrounded by granulosa cells into the peritoneal cavity. Anatomy and Physiology 2013-06-19T00:00:00Z Once the follicle is mature, it ruptures and releases the oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z In addition to its mucus-secreting cells, the inner mucosa contains ciliated cells that beat in the direction of the uterus, producing a current that will be critical to move the oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z The technique is also likely to be important in countries such as Germany where interfering with or freezing of embryos is banned but analysis of oocyte or egg cells is allowed. First babies born in IVF full gene screening study 2010-10-15T13:24:00Z Dr. Jones said that while he did not realize it at the time, he now believes that he and Dr. Edwards created a fertilized human oocyte in a Johns Hopkins laboratory in 1965. Profile | Dr. Howard W. Jones Jr.: Pioneer Reflects on Future of Reproductive Medicine 2010-03-22T19:36:00Z Following ovulation, the secondary oocyte surrounded by a few granulosa cells is released into the peritoneal cavity. Anatomy and Physiology 2013-06-19T00:00:00Z The final stages of development of a small cohort of tertiary follicles, ending with ovulation of a secondary oocyte, occur over a course of approximately 28 days. Anatomy and Physiology 2013-06-19T00:00:00Z The ovulated oocyte with its surrounding granulosa cells is picked up by the infundibulum of the uterine tube, and beating cilia help to transport it through the tube toward the uterus. Anatomy and Physiology 2013-06-19T00:00:00Z Thus, the race into the uterine tubes, which is the most typical site for sperm to encounter the oocyte, is reduced to a few thousand contenders. Anatomy and Physiology 2013-06-19T00:00:00Z If the sperm do not encounter an oocyte immediately, they can survive in the uterine tubes for another 3–5 days. Anatomy and Physiology 2013-06-19T00:00:00Z In comparison, an oocyte can survive independently for only approximately 24 hours following ovulation. Anatomy and Physiology 2013-06-19T00:00:00Z Typically only one follicle, now called the dominant follicle, will survive this reduction in FSH, and this follicle will be the one that releases an oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z If they reach the oocyte before capacitation is complete, they will be unable to penetrate the oocyte’s thick outer layer of cells. Anatomy and Physiology 2013-06-19T00:00:00Z Fertilization must occur in the distal uterine tube because an unfertilized oocyte cannot survive the 72-hour journey to the uterus. Anatomy and Physiology 2013-06-19T00:00:00Z As it is swept along the distal uterine tube, the oocyte encounters the surviving capacitated sperm, which stream toward it in response to chemical attractants released by the cells of the corona radiata. Anatomy and Physiology 2013-06-19T00:00:00Z The plasma membrane of that sperm then fuses with the oocyte’s plasma membrane, and the head and mid-piece of the “winning” sperm enter the oocyte interior. Anatomy and Physiology 2013-06-19T00:00:00Z The LH surge induces many changes in the dominant follicle, including stimulating the resumption of meiosis of the primary oocyte to a secondary oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z Meiosis of a secondary oocyte is completed only if a sperm succeeds in penetrating its barriers. Anatomy and Physiology 2013-06-19T00:00:00Z Zonal inhibiting proteins cause the release of any other attached sperm and destroy the oocyte’s sperm receptors, thus preventing any more sperm from binding. Anatomy and Physiology 2013-06-19T00:00:00Z The two haploid nuclei derived from the sperm and oocyte and contained within the egg are referred to as pronuclei. Anatomy and Physiology 2013-06-19T00:00:00Z Right before the ova would be released from the ovary, they are harvested using ultrasound-guided oocyte retrieval. Anatomy and Physiology 2013-06-19T00:00:00Z |
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