In order to reach its full potential, human embryonic stem cell (hESC) research requires the use of human oocytes. There is currently a shortage of human eggs for research, and this shortage is likely to continue, as many states and countries prohibit their sale for research purposes, while at the same time condoning unregulated markets for oocytes for use in assisted reproduction. In this essay I first explore possible alternative sources of oocytes for hESC research and conclude that, at present, (...) women are the best source. I then examine arguments about exploitation and commodification that are often raised to prohibit payment to women for oocytes in both the reproductive and research contexts and find these arguments wanting. I conclude by suggesting that ethical concerns raised about a market in oocytes do not warrant a prohibition on the sale of eggs, but that a regulated market can consistently minimize ethical concerns while respecting women and providing important resources for advances in hESC research. (shrink)

Assisted reproductive technology is a complex medical intervention with many potential social sensitivities. Within this domain, oocyte cryopreservation has emerged as an important research area for preserving female fertility. Against the backdrop of the hotly debated first legal case in China of a single woman wishing to freeze her eggs, and the implementation of the ‘three‐child policy’ in China, there is an urgent need to evaluate policies and address ethical considerations surrounding oocyte cryopreservation for non‐medical reasons. This review (...) examines current policies, explores China's practices and research, and examines the latest ethical challenges surrounding non‐medical oocyte cryopreservation. It develops strategies and recommendations that will be relevant in China and other developing countries seeking to navigate this complex landscape. (shrink)

Fully grown Xenopus oocytes can remain in their immature state essentially indefinitely, or, in response to the steroid hormone progesterone, can be induced to develop into fertilizable eggs. This process is termed oocyte maturation. Oocyte maturation is initiated by a novel plasma membrane steroid hormone receptor. Progesterone brings about inhibition of adenylate cyclase and activation of the Mos/MEK1/p42 MAP kinase cascade, which ultimately brings about the activation of the universal M phase trigger Cdc2/cyclin B. Oocyte maturation provides (...) an interesting example of how signaling cascades entrain the cell cycle clock to environmental changes. BioEssays 21:833–842, 1999. © 1999 John Wiley & Sons, Inc. (shrink)

In Western countries, a social trend toward delaying childbearing has been observed in women of reproductive age for the last two decades. This delay is due to different factors related to lifestyle, such as the development of a professional career or the absence of the right partner. As a consequence, women who defer childbearing may find themselves affected by age-related infertility when they decide to conceive. Fertility preservation techniques are, therefore, proposed as a solution for these women. Among all possible (...) solutions, social freezing is an alternative strongly discussed from a scientific, social and ethical point of view.A survey among 930 female students at the University of Padova (Italy) investigated their knowledge and attitudes on social egg freezing and their potential intentions regarding this procedure. To our knowledge, this is the first study to examine the level of awareness of age-related infertility in Italian young women and their attitudes regarding acceptable indications for elective oocyte freezing, their potential personal use, the circumstances in which they would then decide to use cryopreserved eggs, and their attitudes towards cost coverage and oocyte donation.Data collected in this study revealed some important points about young women and their knowledge about social oocyte freezing in Italy as compared to other European countries and the United States.Overall, 34.3% of the students reported having heard about the possibility of oocyte cryopreservation for non-medical reasons and being aware of the meaning of this procedure; only 19.5% were in favour of social egg freezing and 48.4% thought that the cost for this procedure should be borne entirely by the woman herself. Regarding egg donation, the majority of students (64.9%) would not accept donating their eggs to a known woman or couple and 42.5% would instead accept donating to a biobank.Our study shows that young Italian women are significantly less aware of age-related decline in fertility and the possibility of using social egg freezing compared to their similarly situated counterparts in other Western countries. (shrink)

This book examines the contemporary biopolitical significance of an emerging global market for oocytes. Reproductive cells specific to biological females, oocytes are increasingly circulated far and wide between social locations. Given the new possibilities for their use, management, and exchange, Waldby employs a feminist perspective to examine the gendered experiences that yield a highly personal valuation of oocytes. Drawing on Raymond Williams's "structures of feeling", she aims to give qualitative texture to the affective dimensions of human eggs and the complex (...) ways in which these intersect with the lives of women.New technical developments have rendered oocytes more profitable because they can... (shrink)

We examine whether the current regulatory regime instituted in South Korea and the United States would have prevented Hwang’s potential transgressions in oocyte procurement for somatic cell nuclear transfer, we compare the general aspects and oversight framework of the Bioethics and Biosafety Act in South Korea and the US National Academies’ Guidelines for Human Embryonic Stem Cell Research, and apply the relevant provisions and recommendations to each transgression. We conclude that the Act would institute centralized oversight under governmental auspices (...) while the Guidelines recommend politically-independent, decentralized oversight bodies including a special review body for human embryonic stem cell research at an institutional level and that the Guidelines would have provided more vigorous protection for the women who had undergone oocyte procurement for Hwang’s research than the Act. We also suggest additional regulations to protect those who provide oocytes for research in South Korea. (shrink)

Reproductive diseases are a long‐standing problem and have become more common in the world. Currently, 15% of the world's population suffers from infertility, and half of them are women. Maturation of oocytes, successful fertilization, and high‐quality embryos are prerequisites for pregnancy. With the development of assisted reproductive technology and advanced genetic assays, we have found that infertility in many young female patients is caused by mutations in various developmental regulators. These pathogenic factors may result in impediment of oocyte maturation, (...) failure of fertilization or early embryonic development arrest. In this review, we categorize these clinically‐identified, mutated genetic factors by their molecular characteristics: nuclear factors (PALT2, TRIP13, WEE2, TBPL2, REC114, MEI1 and CDC20), cytoplasmic factors (TLE6, PADI6, NLRP2/5, FBXO43, MOS and BTG4), a factor unique to primates (TUBB8), cell membrane factor (PANX1), and zona pellucida factors (ZP1‐3). We compared discrepancies observed in phenotypes between human and mouse models to provide clues for clinical diagnosis and treatment of related reproductive diseases. (shrink)

Meiotic defects cause abnormal chromosome segregation leading to aneuploidy in mammalian oocytes. Chromosome segregation is particularly error‐prone in human oocytes, but the mechanisms behind such errors remain unclear. To explain the frequent chromosome segregation errors, recent investigations have identified multiple meiotic defects and explained how these defects occur in female meiosis. In particular, we review the causes of cohesin exhaustion, leaky spindle assembly checkpoint (SAC), inherently unstable meiotic spindle, fragmented kinetochores or centromeres, abnormal aurora kinases (AURK), and clinical genetic variants (...) in human oocytes. We mainly focus on meiotic defects in human oocytes, but also refer to the potential defects of female meiosis in mouse models. (shrink)

Gilbert Meilaender has been an important contributor to the field of bioethics for decades. His insistence that there is a natural teleology of the body that should constrain ambitions of the will in bioethics deserves careful attention. This article examines the idea of a natural teleology of the body as it applies to human oocytes. It argues that approaching human eggs in terms of their telos rather than their moral status is useful. The article examines how Meilaender deploys the idea (...) of a natural teleology to reject John Robertson’s work on assisted reproduction, particularly his preoccupation with procreative liberty. Finally, the article raises questions about the sharp contrast Meilaender draws between teleology and intentionality. (shrink)

In order to accommodate for the present shortage of oocyte donors, oocyte-donation programs place ads in college newspapers and provide large monetary compensation to encourage participation. Large compensation acts as a strong incentive for young women to undergo the potentially risky procedure of donation. In this enticing situation, it is particularly important for programs to fully inform prospective donors of the risks of the procedure so that they can accurately weigh the costs and benefits of donating. However, because (...) oocyte-donor programs must alleviate the shortage of donors if they wish to maintain a financially viable business, there is reason to fear that they may minimize or misrepresent risks when recruiting egg donors. In this pilot study, the risk information provided by programs (n=19) to prospective oocyte donors in a preliminary phone call inquiry was investigated. The majority of the programs provided incomplete and/or inaccurate risk information. Policy changes are recommended to reduce the potential for undue influence and to standardize and regulate the risk information provided to prospective egg donors. (shrink)

Production of oocytes from pluripotent cell cultures in a dish represents a new paradigm in stem cell and developmental biology and has implications for how we think about life. The spark of life for the next generation occurs at fertilization when sperm and oocyte fuse. In animals, gametes are the only cells that transmit their genomes to the next generation. Oocytes contain in addition a large cytoplasm with factors that direct embryonic development. Reconstitution of mouse oocyte and embryonic (...) development in culture provides experimental opportunities and facilitates an unprecedented understanding of molecular mechanisms. However, the application of in vitro gametogenesis to reproductive medicine or infertility treatment remains challenging. One significant concern is the quality of in vitro‐derived oocytes. Here, we review the current understanding and identify limitations in generating oocytes in vitro. From this basis, we explore opportunities for future improvements of the in vitro approach to generating high‐quality oocytes. (shrink)

Freezing Fertility: Oocyte Cryopreservation and the Gender Politics of Aging is the fourth path-breaking monography in the flourishing literature on egg freezing in just a few years. In April 2019, The Oocyte Economy: The Changing Meaning of Human Eggs by the renowned Australian social scientist Catherine Waldby, was published, the first book to examine the emergence of a global market for eggs through biomedical innovation. In September 2019, sociologist Kylie Baldwin of De Montfort University published Egg Freezing, Fertility (...) and Reproductive Choice: Negotiating Responsibility, Hope and Modern Motherhood, in which she explores the experiences of some pioneering women who are having eggs frozen in the United... (shrink)

The American Journal of Bioethics, Volume 11, Issue 9, Page 42-43, September 2011.

The February 1997 announcement of the birth of Dolly, the sheep cloned from a mammary cell of an adult ewe, has drawn attention to the growing ability to select, alter, or otherwise manipulate the genome of offspring. Prior to Dolly, ethical discussion of genes in reproduction had focused on negative selection: carrier screening, prenatal diagnosis, and abortion or embryo discard. After Dolly, ethical debate will have to consider the direct or positive use of genetic selection or alteration technology.The principal use (...) of genetic selection techniques in human reproduction likely will be to treat or prevent disease in offspring. In the future, however, such techniques might also be used to enhance or even diminish expected characteristics of progeny. Techniques to accomplish these goals are likely to include: selection of the nuclear genome, as occurs in somatic cell cloning; chromosomal transplants; or direct insertion or deletion of specific genes. (shrink)

Cellular interactions in the mammalian ovarian follicle between its germ‐line and somatic cell components are crucial for its development and function. These interactions are mediated by both membrane gap junctions and paracrine factors. Somatic cell‐to‐oocyte communication is essential for oocyte growth and the regulation of meiotic maturation. In particular, granulosa cells provide nutrients and molecular signals that regulate oocyte development. Oocytes, on the other hand, promote the organization of the follicle, the proliferation of granulosa cells, and the (...) differentiation and function of cumulus cells, a subset of granulosa cells. Determining the nature of the oocyte‐to‐granulosa cell signals remains a key challenge for future work. (shrink)

Central to the differentiation and patterning of the Drosophila oocyte is the asymmetric intracellular localization of numerous mRNA and protein molecules involved in developmental signalling. Recent advances have identified some of the molecules mediating oocyte differentiation, specification of the anterior pole of the embryo, and determination of the embryonic germ line. This work is considered in the context of the classical model of the germ plasm as a cytoplasmic determinant for germ cell formation.

In vitro fertilization with reception of oocytes from partners allows lesbian mothers to share biological motherhood. The gestational mother receives an egg from her partner who becomes the genetic mother. This article examines the ethics of IVF with ROPA with a focus on the welfare of the woman and the resulting child, on whether ROPA qualifies as a “legitimate” medical therapy that falls within the goals of medicine, and on the meaning and value attributed to a biologically shared bond between (...) parents and child. We also contrast IVF with ROPA with egg donor IVF for heterosexual couples and intrafamilial live uterus transplantation with IVF, and show how Swedish legislation makes certain ways of sharing biological bonds out of place. In Sweden, IVF with ROPA is illegal, egg donor IVF for heterosexual couples is allowed and practiced as is sperm donor IVF for lesbians, and live uterus transplantation is performed within a research project. But is ROPA really ethically more problematic than these other cases? The article argues that IVF with ROPA gives rise to fewer ethical questions than does live uterus transplantation with IVF and, in some cases, egg donor IVF. (shrink)

In China, a prominent case exists wherein a medically fit woman filed a lawsuit against a hospital for denying her request to undergo oocyte cryopreservation. She contended the hospital had infringed upon her rights. This paper focuses on medicalization and gender equality to discuss whether or not a hospital can infringe upon a woman's rights. We believe elective oocyte cryopreservation is not a medical treatment and it may lead to an overwhelming utilization of extensive medical resources. Reproductive medicine (...) may face the risk of resource commercialization due to the practice of selective egg freezing. There are physiological disparities between males and females. The ability of men to cryopreserve sperm does not necessarily extend to a woman's capacity for oocyte cryopreservation. We contend that the application of this technology should continue to adhere to the principle of prudence. (shrink)

This essay aims to tell the story of the “altered nuclear transfer-oocyte assisted reprogramming,” or ANT-OAR, proposal—from its conception by Professor William Hurlbut of the President’s Council on Bioethics—to its adoption and promotion by a group of conservative, mostly Catholic philosophers, theologians and scientists—to its eventual demise in Congress. It also will give some reflections on how ANT-OAR promotes a genetically deterministic view of the human organism and can lead down a slippery slope into a future in which human (...) cloning and human genetic engineering are more acceptable. For these reasons, it will be argued, ANT-OAR should be opposed by all who are against human genetic modification regardless of their political orientation. (shrink)

The protein kinase C (PKC) family comprises enzyme kinases that regulate cell survival, metabolism, and proliferation. PKC isotypes (PKCs) phosphorylate specific downstream substrates, thereby controlling critical steps in both mitotic and meiotic cell division. Throughout the cell cycle, PKCs orchestrate essential processes, such as chromosome segregation, recombination, and cell cycle progression. In vertebrates, PKCs play essential roles in oogenesis and the early stages of embryo development. Disruption of PKC signaling in mammalian oocytes can lead to errors in chromosome segregation and (...) induce meiotic arrest. Therefore, investigating PKC function in meiosis is crucial for advancing fundamental biological research and for developing new approaches to infertility treatment. (shrink)

In vitro fertilization using donated oocytes is an important medical technique that provides the only option for some infertile patients to have children. The technique remains ethically contentious, however, and, as a result of this controversy, different oversight approaches have been developed in countries around the world. This paper examines the oversight and practice of oocyte donation in Canada, the United Kingdom and the United States to examine how policy choices have influenced the development and use of this medical (...) technology. Examining per capita utilization of oocyte donation in these three countries provides evidence that supply-side policies—specifically policies affecting the compensation of potential oocyte donors—have substantially influenced the use of this technology. These results should provide useful insight for policymakers developing or revising oocyte donation policies. (shrink)

What makes something an embryo—as opposed to what is actually, and not just in biotech parlance, a collection of cells? This question has come to the fore in recent years with proposals for producing embryonic stem cells for research. While some of those opposed to use of standard embryonic stem cells emphasise that adult cells have a clinical track record, others argue that there may be further benefits obtainable from cells very like those of embryos, provided such cells can be (...) derived in new ways. Rather than deriving them in ways that kill or otherwise endanger a living human embryo, they could be obtained from an entity that merely resembles a human embryo sufficiently closely for its cells to be of use. Such an entity might be created after introducing genetic changes to an ovum before it is activated by, for example, a cloning-type procedure, such that a gene essential to embryogenesis will be either absent, blocked in its expression, or overexpressed.1,2 The claim is that the ovum could be made to give rise to embryonic stem cells—mere living parts—without ever giving rise to a whole embryo, who is killed to obtain them. Whereas cloning “proper” winds back the specialisation of the cell nucleus to a point where a whole embryo is formed who has not yet specialised its cells, oocyte-assisted reprogramming , it is claimed, would wind back the specialisation merely to an intermediate point at which no embryo is created. Other methods proposed for deriving pseudoembryonic cells include parthenogenesis, in which an ovum is activated without a sperm, or even the insertion of an adult cell nucleus.1MORAL STATUS OF THE EMBRYOIn this paper, I assume that a genuine …. (shrink)

BACKGROUND: Anonymity remains the more common practice in gamete donations, but legislation prohibiting anonymity with a goal of protecting donor-conceived children's right to know their genetic origins is becoming more common. However, given the dearth of research investigating the function of anonymity for donors and recipients, it is unclear whether these policies will accomplish their goals. The aim of this study was to explore experiences with anonymity among oocyte donors and recipients who participated in an anonymous donor oocyte (...) program and to understand the ways in which anonymity functions for them. METHODS: Semistructured interviews were conducted with 50 women: 28 oocyte donors and 22 recipients who were recruited from an academic center for reproductive medicine in the United States. RESULTS: Donors and recipients view anonymity both as a mechanism to protect the interests of all parties (recipients, donors, and donor-conceived children) and as a point of conflict. Specifically, three key areas were identified where both donors and recipients saw anonymity as having an important role: relieving anxieties about family structures and obligations; protecting their interests and those of donor-conceived children (while acknowledging where interests conflict); and managing the future. CONCLUSION: As gamete donation increasingly moves away from the practice of anonymity, examining why anonymity matters to stakeholders will be helpful in devising strategies to successfully implement identity-release options. (shrink)

It is now clear that two prominent nuclear domains, interchromatin granule clusters (IGCs) and Cajal bodies (CBs), contribute to the highly ordered organization of the extrachromosomal space of the cell nucleus. These functional domains represent structurally stable but highly dynamic nuclear organelles enriched in factors that are required for different nuclear activities, especially RNA biogenesis. IGCs are considered to be the main sites for storage, assembly, and/or recycling of the essential spliceosome components. CBs are involved in the biogenesis of several (...) classes of small RNPs as well as the modification of newly assembled small nuclear RNA. We have summarized data on the molecular composition, structure, and functional roles of IGCs and CBs in the nuclei of mammalian somatic cells and oocytes of some animals with a special focus on insects. We have focused on similarities and differences between the IGCs and CBs of oocytes and the well‐studied CBs and IGCs of cultured mammalian somatic cells. We have shown the heterogeneous character of oocyte IGCs and CBs, both in structure and molecular content. We have also demonstrated the unique capacity of oocytes to form close structural interactions between IGC and CB components. We proposed to consider these joint structures as integrated entities, sharing the features of both IGCs and CBs. (shrink)

Elective egg freezing for fertility preservation - commonly referred to as social egg freezing or non-medical egg freezing, will be permitted in Singapore from 2023. There...

Oocyte donation raises conflicts of interest and commitment for physicians but little attention has been paid to how to reduce these conflicts in practice. Yet the growing popularity of assisted reproduction has increased the stakes of maintaining an adequate oocyte supply and minimizing conflicts. A growing body of professional guidelines, legal challenges to professional self-regulation, and empirical research on the practice of oocyte donation all call for renewed attention to the issue. As empirical findings better inform existing (...) conflicts and their potential harms, we can better attempt to reduce these conflicts. To that end, the article first describes the nature of conflicts in oocyte donation and relevant regulations and professional guidelines. We then describe studies on conflicts at four phases of oocyte donation: recruitment, screening, stimulation, and post-stimulation monitoring. Next we consider three models for conflict reduction in medicine generally: improved professional self-regulation, outright restriction like Stark anti-referral laws, or the use of conflict mediators, like in living organ donation. We ultimately conclude that improved professional self-regulation is a reasonable starting place for oocyte donation. (shrink)

Mammalian oocytes exhibit a series of cell cycle transitions that coordinate the penultimate events of meiosis with the onset of embryogenesis at fertilization. The execution of these cell cycle transitions, at G2/M of meiosis‐I and metaphase/anaphase of meiosis I and II, involve both biosynthetic and post‐translational modifications that directly modulate centrosome and microtubule behavior. Specifically, somatic cells alter the signal transduction pathways in the oocyte and influence the expression of maturation promoting factor (MPF) and cytostatic factor (CSF) activity through (...) a microtubule‐dependent mechanism. The regulation of the oocytes' cell cycle machinery by hormone‐mediated somatic cell signals, involving both positive and negative stimuli, ensures that meiotic cell cycle progression is synchronized with the earliest pivotal events of mammalian reproduction. (shrink)

The oocyte is not only the rarest and the largest cell in the body, but it also has one of the most remarkable life histories. Formed in the fetal ovary and suspended at diplotene of meiosis, it may wait for years before beginning to grow, and not until this process is complete can it resume meiosis and undergo fertilisation. Major changes in the number, morphology and distribution of cytoplasmic organelles occur during growth, and a molecular program for embryogenesis is (...) formed. Specific yolk proteins are absent and much of the RNA and some of the protein are degraded by the cleavage stage. The zona pellucida has been intensively studied, but knowledge of oocyte‐specific genes is otherwise surprisingly patchy given the significance of this cell type and the expansion of reproductive technology. Finally, it is now clear that oocytes are not mere passengers which depend on granulosa cells for nutrition and regulation but actively promote the growth and differentiation of their follicles. (shrink)

Over the last couple of decades, oocyte donation has become common, important, and sometimes lucrative. Women who donate eggs are often offered fees, though ostensibly only to offset their expenses and limited to no more than $10,000, following recommendations adopted by the fertility industry. Is the industry adhering to its recommendations? A study of advertisements published in college newspapers raises questions.

The American Journal of Bioethics, Volume 11, Issue 9, Page 31-33, September 2011.

The American Journal of Bioethics, Volume 11, Issue 9, Page 35-37, September 2011.

Microinjection of frog oocytes, a technique whose usefulness for studies on gene expression is already established, may be similarly helpful for the unraveling of several enigmas of cellular metabolism and its organization.

There is a growing consensus that the offer of a reasonable compensation for oocyte donation for reproductive treatment is acceptable if it does not compromise voluntary and altruistically motivated donation. However, how to translate this ‘reasonable compensation’ in practice remains unclear as compensation rates offered to oocyte donors between different European Union countries vary significantly. Clinics involved in oocyte donation, as well as those in other medical contexts, might be encouraged in calculating a more consistent and transparent (...) compensation for donors if the elements that constitute a reasonable compensation are explicated. In doing so, lessons can be learnt from living organ donation and medical research participation. Practices in which the elements of a reasonable compensation for the individuals involved have already been more defined in the literature. By means of analogical reasoning, we will outline the different components of a reasonable compensation and subsequently apply these to the context of oocyte donation. We will argue that oocyte donors should first of all be reasonably reimbursed direct expenses related to the donation, without standard remuneration of lost wages. Second, donating oocytes requests a serious time investment, therefore donors are entitled to suitable compensation for their time spent and efforts made. Finally, we will explain that a reasonable compensation consisting of these two components allows for altruism to remain the key value of oocyte donation for reproductive treatment. However, if we acknowledge that donors’ motives are more complex and often include reasons from self-interest, the reasonable compensation may be complemented with modest (non)monetary benefits. (shrink)

One distinguishing feature of vertebrate oocyte meiosis is its discontinuity; oocytes are released from their prophase I arrest, usually by hormonal stimulation, only to again halt at metaphase II, where they await fertilization. The product of the c‐mos proto‐oncogene, Mos, is a key regulator of this maturation process. Mos is a serine‐threonine kinase that activates and/or stabilizes maturation‐promoting factor (MPF), the master cell cycle switch, through a pathway that involves the mitogen‐activated protein kinase (MAPK) cascade. Oocytes arrested at prophase (...) I lack detectable levels of Mos, which must be synthesized from a pool of maternal mRNAs for proper maturation. While Mos is necessary throughout maturation in Xenopus, it seems to be required only for meiosis II in the mouse. The translational activation of c‐mos mRNA at specific times during meiosis requires cytoplasmic polyadenylation. Cis‐ and trans‐acting factors for polyadenylation are, therefore, essential elements of maturation. (shrink)

First put forth in June 2005, the altered nuclear transfer-oocyte assisted reprogramming (ANT-OAR) proposal has been promoted as an ethically-acceptable alternative to the embryo-destructive methods now used to obtain embryonic stem cells. According to its proponents, the goal of ANT-OAR is to use the cloning process to create a pluripotent stem cell. This would be achieved through overexpression of the transcription factor Nanog (or a hypothetical substitute) both in the enucleated egg cell and in the somatic cell prior to (...) transfer of its nucleus. Although the ethical acceptability of ANT-OAR has been publicly debated, its scientific feasibility has not. This paper aims to help rectify this situation. It argues that ANT-OAR, as currently conceived, cannot realistically work. It presents evidence from the scientific literature showing that Nanog cannot single-handedly establish pluripotency in cells, but rather works together with a network of other transcription factors to maintain pluripotency. It argues that ANT-OAR is based on a flawed understanding of stem cell biology, and emphasizes that, in this debate about embryonic stem cells, scientists must strive to accurately and realistically assess the feasibility of the embryo research strategies they propose. (shrink)

RNA localization is a powerful strategy used by cells to localize proteins to subcellular domains and to control protein synthesis regionally. In germ cells, RNA targeting has profound implications for development, setting up polarities in genetic information that drive cell fate during embryogenesis. The frog oocyte offers a useful system for studying the mechanism of RNA localization. Here, we discuss critically the process of RNA localization during frog oogenesis. Three major pathways have been identified that are temporally and spatially (...) separated in oogenesis. Each pathway uses a different mechanism to effect RNA localization. In some cases, localization elements within the 3' untranslated region have been identified and have provided unique insights into the localization process. This important field is still in its infancy, however, and much remains to be learned. BioEssays 21:546–557, 1999. © 1999 John Wiley & Sons, Inc. (shrink)

In vitro fertilization using donated oocytes has proven to be an effective treatment option for many prospective parents struggling with infertility, and the usage of donated oocytes in assisted reproduction has increased markedly since the technique was first successfully used in 1984. Data published by the Centers for Disease Control and Prevention on the use of assisted reproductive technologies in the United States indicate that approximately 12% of all ART cycles in the country now use donated oocytes. The increased use (...) of oocyte donation in the United States has prompted discussion regarding risks associated with the process and how best to ensure the safety of oocyte donors.Physical risks associated with oocyte donation include bleeding, infection, ovarian hyperstimulation syndrome and a potential, although unconfirmed, increased risk of developing various forms of cancer, such as uterine, colon, breast, ovarian, and endometrial cancers. (shrink)

Like all research, embryo research can take a variety of forms, some posing substantially more risks to persons than others. Savulescu et al argue persuasively that regulatory regimes specially designed for sensitive embryo research should differentiate between person-affecting and non-person-affecting embryo research, with substantial scrutiny only warranted for the former.1 Yet if we find Savulescu et al ’s argument persuasive, what practical implications would it have? In this commentary, we focus in particular on how such an argument might apply in (...) Singapore, one of the jurisdictions with special regulations for embryo research. We will summarise the way in which approval for oocyte and embryonic research operates in Singapore, and suggest that Savulesc et al ’s distinction requires specification to be useful in such contexts. We propose adopting a risk-stratified framework similar to that employed with Institutional Review Boards. This requires a wider view of risks than the focus by Savulescu et al on future persons. We then illustrate how such a framework would apply in five scenarios discussed in Savulescu et al. Research with embryos and oocytes is regulated in Singapore under the Human Biomedical Research Act.2 Enacted in 2015, this law sets out requirements for consent, IRB review and research oversight. By definition, all research involving gametes and embryos fall within the remit of the Act. Moreover, such research is defined as ‘restricted’; besides the Act, research involving oocytes and embryos is also subject to control under the Human Biomedical Research …. (shrink)

Mammalian sperm undergo discharge of a single, anterior secretory granule following their attachment to the zona pellucida surrounding the oocyte. This secretory discharge is known for historical reasons as the acrosome reaction. It fulfils a number of purposes and without it, sperm are unable to penetrate the zona pellucida and fuse with the oocyte. In this review, we focus on the role of the acrosome reaction in the development of fusion competence in sperm. Any naturally occurring membrane fusion (...) has two major sequential steps: a docking or adhesion step, in which two membranes adhere, and a fusion step, in which their lipid bilayers are destabilized and merged and a cellular compartment is either created or destroyed. Recent evidence suggests that there is an important role for oocyte integrins and sperm‐bound disintegrins in mammalian sperm/oocyte adhesion and fusion. The fusion mechanism employed by sperm remains poorly understood, however, and circumstantial evidence suggests it is more complex than the interaction between a single protein species and its target. Sperm/oocyte fusion is probably the most accessible eukaryotic model for intercellular fusion currently available, partly because it is temporally separated from gene expression. Elucidation of the mechanism of sperm/oocyte fusion may throw light on the mechanism of other intercellular fusions such as myoblast fusion, and the evolutionary relationship of intercellular membrane fusion to intracellular membrane fusion. (shrink)

Under certain conditions, the cell cycle can be arrested for a long period of time. Vertebrate oocytes are arrested at G2 phase, while somatic cells arrest at G0 phase. In both cells, nuclei have lost the ability to initiate DNA synthesis. In a pair of recently published papers,1,2 Méchali and colleagues and Coué and colleagues have clarified how frog oocytes prevent untimely DNA synthesis during the long G2 arrest. Intriguingly, they found only Cdc6 is responsible for the inability of immature (...) oocytes to replicate DNA. Cdc6 is a key component for replication licensing, and for G0 cells to re‐enter the proliferative stage. Strikingly similar strategies for preventing the untimely replication in both cells suggest that the suppression of replication licensing is a universal mechanism for securing the prolonged arrest of the cell cycle. BioEssays 25:313–316, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Infertility is a huge problem nowadays, not only from the medical but also from the social point of view. A key step to improve treatment outcomes is the possibility of effective prediction of treatment result. In a situation when a phenomenon with more than 2 states needs to be explained, e.g. pregnancy, miscarriage, non-pregnancy, the use of multinomial logistic regression is a good solution. The aim of this paper is to select those features that have a significant impact on achieving (...) clinical pregnancy as well as those that determine the occurrence of spontaneous miscarriage. Two multi-factor models were obtained, used in predicting infertility treatment outcomes. One of the models enabled to conclude that the number of follicles and the percentage of retrieved mature oocytes have a significant impact when prediction of treatment outcome is made on the basis of information about oocytes. The other model, built on the basis of information about embryos, showed the significance of the number of fertilized oocytes, the percentage of at least 7-cell embryos on day 3, the percentage of blasts on day 5, and the day of transfer. (shrink)