DNA methylation can be considered a component of epigenetic memory with a critical role during embryo development, and which undergoes dramatic reprogramming after fertilization. Though it has been a focus of research for many years, the reprogramming mechanism is still not fully understood. Recent results suggest that absence of maintenance at DNA replication is a major factor, and that there is an unexpected role for TET3-mediated oxidation of 5mC to 5hmC in guarding against de novo methylation. Base-resolution and (...) genome-wide profiling methods are enabling more comprehensive assessments of the extent to which ART might impair DNA methylation reprogramming, and which sequence elements are most vulnerable. Indeed, as we also review here, studies showing the effect of culture media, ovarian stimulation or embryo transfer on the methylation pattern of embryos emphasize the need to face ART-associated defects and search for strategies to mitigate adverse effects on the health of ART-derived children. DNA methylation, critical for embryo development, suffers significant changes after fertilization, including demethylation, remethylation and TET3-mediated oxidation of 5 mC to 5 hmC. In addition to infertility and environmental insults, ART could impact DNA methylation and ART related consequences in the offspring have been reported. (shrink)

It is generally assumed that the developmental program of embryogenesis relies on epigenetic mechanisms. However, a mechanistic link between epigenetic marks and cell fate decisions had not been established so far. In a recent article, Torres‐Padilla and colleagues1 show that epigenetic information and, more precisely, histone arginine methylation mediated by CARM1 could contribute to cell fate decisions in the mouse 4‐cell‐stage embryo. It provides the first indications that global epigenetic information influences allocation of pluripotent cells toward the first cell (...) lineages. BioEssays 29:520–524, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

The founding of the Carnegie Institute’s Department of Embryology in 1913, alongside its systematization of embryo staging, contributed to the mechanization of developmental stages of embryo growth in the early 20th century. For a brief period in the middle of the century, attention to the detailed interrelation between embryo development and time made pre-existing ideas about pregnancy ends less determinative of ideas about that developmental course. However, the turn to the genetic scale led to the disappearance (...) of this attention, replaced by a sense of biological life as seamlessly scripted. This study examines the history of what I refer to as temporal attention: attention to the live, unfolding potentialities within vital matter. The reintroduction of temporal attention to discussions of development allows us to more fully consider non-human vitality and the experiences of beings that house or otherwise intimately intersect with that vital tissue, regardless of outcomes. (shrink)

We have discovered that a single sperm protein, phospholipase C‐zeta (PLCζ), can stimulate intracellular Ca2+ signalling in the unfertilized oocyte (‘egg’) culminating in the initiation of embryonic development. Upon fertilization by a spermatozoon, the earliest observed signalling event in the dormant egg is a large, transient increase in free Ca2+ concentration. The fertilized egg responds to the intracellular Ca2+ rise by completing meiosis. In mammalian eggs, the Ca2+ signal is delivered as a train of long‐lasting cytoplasmic Ca2+ oscillations that (...) begin soon after gamete fusion and persist beyond the completion of meiosis. Sperm PLCζ effects Ca2+ release from egg intracellular stores by hydrolyzing the membrane lipid PIP2 and consequent stimulation of the inositol 1,4,5‐trisphosphate (InsP3) receptor Ca2+‐signalling pathway, leading to egg activation and early embryogenesis. Recent advances have refined our understanding of how PLCζ induces Ca2+ oscillations in the egg and also suggest its potential dysfunction as a cause of male infertility. (shrink)

The development of the human embryo from the time of fertilization through the eighth post-fertilization week is described for medical policy purposes. During pre-implantation stages, differentiation occurs between precursors of embryonic and extra-embryonic structures. During implantation formation of a fore-hind axis begins within the inner cell mass. By the end of the eighth week, head, face, hands, and feet are suggestive as to species-recognition but not yet definitive. Data from laboratory studies of non-human mammalian embryos elucidate important aspects (...) of human embryonic development. Keywords: embryos, development, differentiation, genome CiteULike Connotea Del.icio.us What's this? (shrink)

Every cartilage and bone in the vertebrate skeleton has a precise shape and position. The head skeleton develops in the embryo from the neural crest, which emigrates from the neural ectoderm and forms the skull and pharyngeal arches. Recent genetic data from mice and zebrafish suggest that cells in the pharyngeal segments are specified by positional information in at least two dimensions, Hox genes along the anterior‐posterior axis and other homeobox genes along the dorsal‐ventral axis within a segment. Many (...) zebrafish and human mutant phenotypes indicate that additional genes are required for the development of groups of adjacent pharyngeal arches and for patterning along the mediolateral axis of the skull. The complementary genetic approaches in humans, mice and fish reveal networks of genes that specify the complex morphology of the head skeleton along a relatively simple set of coordinates. (shrink)

One of the most significant developments in the area of reproductive health in Ireland is theRoche v. Roche[2009] case. The case concerned a woman who wished to implant cryopreserved embryos made with a former partner, against the partner’s wishes. Of particular interest are questions about the status of the embryo: in Ireland the life of “the unborn” is constitutionally protected. Therefore the courts inRochehad to decide whether embryos were “unborn” within the meaning of the Irish Constitution.

One major milestone in the development of the sea urchin embryo is the assembly of a single cilium on each blastomere just before hatching. These cilia are constructed both from pre‐existing protein building blocks, such as tubulin and dynein, and from a number of 9+2 architectural elements that are synthesized de novo at ciliogenesis. The finite or quantal synthesis of certain key architectural proteins is coincident with ciliary elongation and proportional to ciliary length. Upon deciliation, the synthesis of (...) architectural proteins occurs anew, a new cilium grows, and the stores of various building blocks are replenished. This routine of coordinated ciliary gene expression may be replayed experimentally many times without delaying normal development. The ability to regenerate cilia has allowed elucidation of these various protein synthetic relationships and has led to the discovery of the pathways by which membrane‐associated tubulin and axoneme‐associated architectural proteins are conveyed into the highly compartmentalized growing cilium. The sea urchin embryo thus provides a very convenient model system for studies of ciliary assembly and maintenance, coordinate gene expression and membrane dynamics. (shrink)

Glial cells play a central role in the development and function of complex nervous systems. Drosophila is an excellent model organism for the study of mechanisms underlying neural development, and recent attention has been focused on the differentiation and function of glial cells. We now have a nearly complete description of glial cell organization in the embryo, which enables a systematic genetic analysis of glial cell development. Most glia arise from neural stem cells that originate in (...) the neurogenic ectoderm. The bifurcation of glial and neuronal fates is under the control of the glial promoting factor glial cells missing. Differentiation is propagated through the regulation of several transcription factors. Genes have been discovered affecting the terminal differentiation of glia, including the promotion glial–neuronal interactions and the formation of the blood–nerve barrier. Other roles of glia are being explored, including their requirement for axon guidance, neuronal survival, and signaling. BioEssays 23:877–887, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

Viktor Hamburger was a developmental biologist interested in the ontogenesis of the vertebrate nervous system. A student of Hans Spemann at Freiburg in the 1920s, Hamburger picked up a holistic view of the embryo that precluded him from treating it in a reductionist way; at the same time, he was committed to a materialist and analytical approach that eschewed any form of vitalism or metaphysics. This paper explores how Hamburger walked this thin line between mechanistic reductionism and metaphysical vitalism (...) in light of his work on the factors influencing growth of neurons into limb buds, and the discovery of nerve growth factor, work carried out with Rita Levi-Montalcini and Stanley Cohen. (shrink)

The stereotyped pattern of cell commitments during leech embryogenesis is described. The nature of cell commitments during segmentation differs significantly between leech and fruit fly. Despite the constancy of cell fate assignments in normal development, ablation experiments show that cell interactions are essential in setting some of these commitments. Interacting cells follow a positionally determined hierarchy of fate choices. For other cells, which appear to have fates fixed from birth, the possibility of determinative interactions between mother and daughter cells (...) is discussed. (shrink)

A considerable challenge confronts, any developing neuron. Before it can establish a functional and specific connection, it must extend an axon over tens and sometimes hundreds of microns through a complex and mutable environment to reach one out of many possible destinations. The field of axonal guidance concerns the control of this navigation process. To satisfactorily identify the cell interactions and molecular mechanisms that mediate axonal guidance, it is essential to first identify the pertinent cell populations. Embryonic surgeries have provided (...) solid information on which tissues are critical and which are irrelevant to the navigation of motor axons within the chick embryo. The gross anatomical nerve pattern is established as axons respond to both positive (path) and negative (barrier) tissue environments. Analysis of the interactions of motoneurons with these tissues reveals that several cellular interactions – chemotaxis, substratum preference, and perhaps contact paralysis – are important to the common patterns of motor axon advance. Axons simultaneously interact with population‐specific cues that have begun to be identified on the tissue level. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:At the Vortex of Controversy:Developing Guidelines for Human Embryo ResearchRonald M. Green (bio)Because of the unavoidable time delay between the submission and publication of this article, its readers will have a significant advantage over its writer: You will know whether the recommendations of the Report of the Human Embryo Research Panel, on which I have served as a member since its inception in January of this year, (...) are progressing smoothly as the basis for evaluating future, federally-funded embryo research—or whether any of the recommendations has become stalled in controversy and political dispute. Staid journals like Science already are predicting that the Panel's Report is likely to create a stormy autumn for the National Institutes of Health.The Panel formally presented its Report to NIH Director Harold Varmus on September 27. The Panel's recommendations will be reviewed by the Advisory Committee to the Director (ACD) until the ACD's next meeting in early December. At that time, the ACD will make formal recommendations to Dr. Varmus, who then will initiate the process of drafting federal regulations that could go into effect by Spring 1995.Historical BackgroundControversy is not new to the area of human embryo research. In the United States, federal regulations enacted in the mid-1970s required any research on the human embryo to be approved by a federally mandated Ethics Advisory Board (EAB). The EAB drafted a significant report that provided ethical guidelines for research on the early, ex utero, human embryo. However, before the report could be acted upon, a new administration, which was opposed to abortion and anything remotely viewed as threatening to prenatal life, came to office, and when the EAB's charter expired in 1980, it was not renewed. In this manner, the Reagan and Bush administrations forestalled any federal support for embryo research in the United States. The next 13 years saw a significant expansion of infertility services in this country, but in the absence of federal funding and [End Page 345] review, there was very little systematic research on either infertility procedures or the human embryo.In January 1993, the U.S. political environment changed again when the Clinton administration fulfilled a campaign promise to remove a nearly five-year-old ban on fetal tissue transplantation research. Although fetal tissue research, which uses the remains of an aborted fetus, significantly differs from embryo research, which involves the developing conceptus ex utero before its transfer to and implantation in a womb, the changed political environment stimulated public discussion of embryo research as well. As a result, in June 1993, Congress nullified the federal regulations requiring EAB review for embryo research. Although this presumably left NIH free to fund embryo research without restrictions, NIH officials felt that guidelines were needed to ensure that such research was conducted in an ethically and socially responsible manner. Accordingly, in January 1994, NIH formed the Human Embryo Research Panel to propose such guidelines.The Panel Begins its WorkChaired by Steven Muller, President emeritus of the Johns Hopkins University, the Panel's 19 members included 7 basic and clinical scientists, 4 ethicists, 2 lawyers, and 6 individuals representing various backgrounds relevant to the making of public policy. Patricia King of the Georgetown University Law Center and Brigid Hogan, a cell biologist at Vanderbilt University, were appointed policy and science co-chairs respectively. Meeting for the first time in early February, the Panel was told by its chair and co-chairs that NIH's need for guidance in the face of pending proposals meant that it had approximately six months—including five one- to two-day meetings each month in Washington—in which to complete its work.In his charge, Dr. Varmus asked the Panel to place the possible areas of research into three categories: (1) acceptable for federal funding; (2) warranting additional review; and (3) unacceptable for federal support. In addition, he asked the Panel to draft guidelines for the review and conduct of the research deemed acceptable.Looking back after months of work, I vividly recall a sense of the enormity of the task facing us. We were being asked, in a short period of time, not only to master... (shrink)

A major obstacel to the study of mammalian development, and to the practical application of knowledge gained from it in the clinic during therapeutic in vitro fertilisation and embryo transfer (IVF‐ET), is the propensity of embryos to become retarded or arrested during their culture in vitro. The precise developmental cell cycle in which embryos arrest or delay is characteristic for the species and coincides with the earliest period of embryonic gene expression. Much evidence reviewed here implicates free oxygen (...) radicals (FORs) in the process of arrest. Thus, studies on the development of mouse preimplantation embryos in vitro have shown that (i) FORs are elevated in vitro, but not in vivo, at the time at which embryos become arrested or delayed, (ii) systems for removing reactive oxygen species to limit the formation of hydroxy radicals are present, although they have not yet been assessed quantitatively and may differ qualitatively from those in adult cells, (iii) metabolic and possibly genetic adaptations to oxidative damage are evident, (iv) published procedures for overcoming in vitro arrest are explicable in terms of FOR‐mediated damage or responses and (v) the arrest or delay of most embryos in vitro can be reduced or prevented experimentally by addition of metal chelators to limit hydroxy radical formation and lipid hydroperoxidation. (shrink)

Rob Lovering has developed an interesting new critique of views that regard embryos as equally valuable as other human beings: the moral argument for frozen human embryo adoption. The argument is aimed at those who believe that the death of a frozen embryo is a very bad thing, and Lovering concludes that some who hold this view ought to prevent one of these deaths by adopting and gestating a frozen embryo. Contra Lovering, we show that there are (...) far more effective strategies for preserving the lives of frozen embryos than adoption. Moreover, we point out that those who regard the deaths of frozen embryos as a very bad thing will generally regard the deaths of all embryos as a very bad thing, whether they are discarded embryos, aborted embryos or embryos that spontaneously abort. This entails these other embryos must be taken into account when considering moral obligations, as well as other human lives at risk from preventable causes. (shrink)

Plant reproduction is vital for species survival, and is also central to the production of food for human consumption. Seeds result from the successful fertilization of male and female gametes, but our understanding of the development, differentiation of gamete lineages and fertilization processes in higher plants is limited. Germ cells in animals diverge from somatic cells early in embryo development, whereas plants have distinct vegetative and reproductive phases in which gametes are formed from somatic cells after the (...) plant has made the transition to flowering and the formation of the reproductive organs. Recently, novel insights into the molecular mechanisms underlying male germ‐line initiation and male gamete development in plants have been obtained. Transcriptional repression of male germ‐line genes in non‐male germ‐line cells have been identified as a key mechanism for spatial and temporal control of male germ‐line development. This review focuses on molecular events controlling male germ‐line development especially, on the nature and regulation of gene expression programs operating in male gametes of flowering plants. BioEssays 29:1124–1132, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

Are embryos deserving of moral consideration in our actions? A standard view suggests that embryos are considerable only if they have interests. One argument for embryonic interests contends that embryos are harmed by death because they are deprived of valuable future lives as adult persons. Some have challenged this argument on the grounds that embryos aren’t identical to adults: either due to the potential for embryos to twin or because we do not exist until the fetus develops consciousness. These arguments (...) fail to show that embryos do not have future adult lives. There is a better reason to think that embryos cannot have interests; namely, because they are not capable of having desires. Others have held this view but have not sufficiently justified it. The justification lies in the fact that the capacity for desires is necessary to make sense of the normativity of interests. (shrink)

Normal fetal development is dependent upon an intricate exchange between mother and embryo. Several maternal and embryonic elements can influence this intimate interaction, including genetic, environmental or epigenetic factors, and have a significant impact on embryo development. The interaction of the genetic program of both mother and embryo, within the uterine environment, can shape the development of an individual. Accumulating data from animal models indicate that prenatal events may well initiate long‐term changes in the (...) expression of the embryo genetic program, which persist, or may only become apparent, much later in the individual's life. Also, environmental conditions during prenatal development may prompt the adoption of different developmental pathways, leading to alternative life histories. This review focuses on environmental factors, specifically maternally derived molecules, to illustrate how they can influence in utero embryonic development and, by extension, adult life. (shrink)

: The transplantation of adult human neural stem cells into prenatal non-humans offers an avenue for studying human neural cell development without direct use of human embryos. However, such experiments raise significant ethical concerns about mixing human and nonhuman materials in ways that could result in the development of human-nonhuman chimeras. This paper examines four arguments against such research, the moral taboo, species integrity, "unnaturalness," and human dignity arguments, and finds the last plausible. It argues that the transfer (...) of human brain or retinal stem cells to nonhuman embryos would not result in the development of human-nonhuman chimeras that denigrate human dignity, provided such stem cells are dissociated. The article provides guidelines that set ethical boundaries for conducting such research that are consonant with the requirements of human dignity. (shrink)

The use of genome embryo editing tools in reproduction is often touted as a way to ensure the birth of healthy and genetically related children. Many would agree that this is a worthy goal. The purpose of this paper is to argue that, if we are concerned with justice, accepting such goal as morally appropriate commits one to rejecting the development of embryo editing for reproductive purposes. This is so because safer and more effective means exist that (...) can allow many more prospective parents to achieve the same valued goal and that offer additional benefits. (shrink)

Embryos, cells, genes, and organisms : reflections on the history of evolutionary developmental biology / Manfred D. Laubichler and Jane Maienschein The organismic systems approach : streamlining the naturalistic agenda / Werner Callebaut, Gerd B. Müller, and Stuart A. Newman Complex traits : genetics, development, and evolution / H. Frederik Nijhout Functional and developmental constraints on life-cycle evolution : an attempt on the architecture of constraints / Gerhard Schlosser Legacies of adaptive development / Roger Sansom Evo-devo meets the (...) mind : toward a developmental evolutionary psychology / Paul E. Griffiths Reproducing entrenchments to scaffold culture : the central role of development in cultural evolution / William C. Wimsatt and James R. Griesemer. (shrink)

Recent scientific advances have indicated that it may be technically feasible to sustain human embryos in vitro beyond 14 days. Research beyond this stage is currently restricted by a guideline known as the 14-day rule. Since the advances in embryo culturing there have been calls to extend the current limit. Much of the current debate concerning an extension has regarded the 14-day rule as a political compromise and has, therefore, focused on policy concerns rather than assessing the philosophical foundations (...) of the limit. While there are relevant political considerations, I maintain that the success of extension arguments will ultimately depend on the strength of the justifications supporting the current 14-day limit. I argue that the strongest and most prevalent justifications for the 14-day rule—an appeal to individuation and neural development—do not provide adequate support for the limit of 14 days. I instead suggest that an alternative justification based on sentience would constitute a more defensible basis for embryo protection and that a consideration of such grounds appears to support an amendment to the current limit, rather than the retention of it. While these conclusions do not establish conclusively that the current limit should be extended; they do suggest that an extension may be warranted and permissible. As such, this paper offers grounds on which a reassessment of the 14-day rule may be justified. (shrink)

New developments in reproductive technology have made headlines since the birth of the world's first in vitro fertilization baby in 1978. But is embryo experimentation ethically acceptable? What is the moral status of the early human embryo? And how should a democratic society deal with so controversial an issue, where conflicting views are based on differing religious and philosophical positions? These controversial questions are the subject of this book, which, as a current compendium of ideas and arguments on (...) the subject, makes an original contribution of major importance to this debate. (shrink)

Ethically sound analyses of embryo genetic editing require more than simple assessments of safety considerations. After all, we as humans care deeply not only about our health, but also care profoundly about the kinds of societies we construct, the injustices that our actions produce, the responsibilities that we have toward others and ourselves, our self-understanding, the characters that we develop, our family relationships, and the world that we leave to our children and grandchildren.

The genomics revolution has altered the very nature of research in molecular biology, from how to find genes to how to find out what specific genes do. Given the availability of so many fully (or nearly) sequenced genomes, it is now relatively easy to track down dozens or even hundreds of genes relevant to a particular field of study. Unfortunately, up till now, the tools for determining what these genes actually do in embryos and cells have not kept pace, but (...) the burgeoning field of bioinformatics should help correct this shortcoming and introduce the power of genomics to the study of developmental biology. In this review, some of the bioinformatics resources relevant to developmental biologists are described along with some simple approaches for applying these tools to analyzing early development. BioEssays 23:549–554, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

In 2018, the Chinese scientist He Jiankui presented his research at the Second International Summit on Human Genome Editing in Hong Kong. While it was intended that he facilitate a workshop, he was instead called on to present his research in heritable human genome editing, where he made the announcement that he had taken great strides in advancement of his research, to the extent that he had gene-edited human embryos and that this had resulted in the live births of two (...) children. While his research ethic and methodology was interrogated, he insisted that two children, twin girls, had been born healthy and that there was another pregnancy (at the time) where birth of a third gene edited child would be imminent. This announcement generated a ripple effect in the scientific community and exposed the gaps in regulation and absence of law relating to the technology. This resulted in a flurry of activity and conversation around regulation of the technology, which scientists stated was not ready for human trials. This article reviews the Third Summit which was held in London in March 2023 and comments on the latest developments in the regulation of heritable human genome editing. (shrink)

At a time when bioethical issues are at the top of public and political agendas, there is a renewed interest in representations of the embryo in various religious traditions. One of the major traditions that have contributed to Western representations of the embryo is the Jewish tradition. This tradition poses some difficulties that may deter scholars, but also presents some invaluable advantages. These derive from two components, the search for limits and narrativity, both of which are directly connected (...) with the manner in which Jewish tradition was constructed in Antiquity. The article accomplishes three goals: • To introduce some central elements in ancient Rabbinic literature on the subject of the embryo and its representation; • To present this body of literature as clearly as possible, noting some of the difficulties encountered by scholars who engage in its study; • To explain how the literature’s textuality came about, examining the particular sociopolitical circumstances of Judaism at that time, including the reasons for the delay in the production of scientific texts, transmitted as such, as compared to other philosophical or religious traditions. The claim is that these circumstances engendered a tradition peculiarly relevant for the study and teaching of medical ethics today. (shrink)

A topological inevitability of early developmental events through the use of classical topological concepts is discussed. Topological dynamics of forms and maps in embryo development are presented. Forms of a developing organism such as cell sets and closed surfaces are topological objects. Maps (or mathematical functions) are additional topological constructions in these objects and include polarization, singularities and curvature. Topological visualization allows us to analyze relationships that link local morphogenetic processes and integral developmental structures and also to find (...) stable spatio-temporal topological characteristics that are invariant for a taxonomic group. The application of topological principles reveals a topological imperative: certain topological rules define and direct embryogenesis. A topological stability of embryonic morphogenesis is proposed and a topological scenario of developmental and evolutionary transformations is presented. (shrink)

The recent publications reported in 2022 reveal the possibility of obtaining mouse embryos without the need for egg or sperm. These ‘artificial embryos’ can recapitulate some stages of development ex utero – from neurulation to organogenesis – without implantation. Synthetic mouse embryos might serve as a valuable model to gain further insights into early developmental stages. Indeed, it is expected for these models to be replicated by employing human cells. This promising research raises ethical issues and expands the horizon (...) of ethics in regard to the development of the human embryo. From this point of view, we state some of the new open venues for bioethical research. (shrink)

Embryos and microscopes share a long, remarkable history and biologists have always been intrigued to watch how embryos develop under the microscope. Here we discuss the advances in microscopy which have greatly influenced our current understanding of embryogenesis. We highlight the evolution of microscopes and the optical technologies that have been instrumental in studying various developmental processes. These imaging modalities provide mechanistic insights into the dynamic cellular and molecular events which drive lineage commitment and morphogenetic changes in the developing (...) class='Hi'>embryo. We begin the journey with a brief history of microscopy to study embryos. First, we review the principles and optics of light, fluorescence, confocal, and electron microscopy which have been key techniques for imaging cellular and molecular events during embryonic development. Next, we discuss recent key imaging modalities such as light‐sheet microscopy, which are suitable for whole embryo imaging. Further, we highlight imaging techniques like multiphoton and super resolution microscopy for beyond light diffraction limit, high resolution imaging. Lastly, we review some of the scattering‐based imaging methods and techniques used for imaging human embryos. (shrink)

Abortion and embryo destruction prevent a future of value, but that does not make them wrong.Abortion involves the killing of a fetus. One bad thing about killing a fetus is that the fetus is deprived of a future of value. Think of all the things which make your life good and worth living: understanding the world, seeing your children grow into independent, intelligent, and happy people, watching a sunset over the hills, enjoying good times with friends. By killing the (...) fetus, we are depriving it of a future life likely to contain these things. And more. The fetus would likely grow to be a person who would have contributed to the world in many ways—bringing joy to its parents, happiness, and friendship to many. That person would have laboured for society and perhaps even discovered a cure for cancer or developed the first bionic eye.The loss of these possible futures is bad. It makes the killing of a fetus wrong. This is Don Marquis's argument against abortion.1 It is one of the best arguments against abortion which does not rest on theological premises.Another way of putting this is to say that we have a good reason not to kill a fetus. A reason for acting is a fact or circumstance forming a sufficient justification for an action. Or in this case, not to perform an action. We have all sorts of reasons for action. Our reasons often conflict. I may have a good reason to visit my mother and a good reason to take my children to the park. What we have most reason to do is what it is right to do. It is what we should do. If we have most reason not to perform an act, …. (shrink)

Stem cell-derived embryo models (SCEMs) are model embryos used in scientific research to gain a better understanding of early embryonic development. The way humans develop from a single-cell zygote to a complex multicellular organism remains poorly understood. However, research looking at embryo development is difficult because of restrictions on the use of human embryos in research. Stem cell embryo models could reduce the need for human embryos, allowing us to both understand early development and (...) improve assisted reproductive technologies. There have been several rapid advances in creating SCEMs in recent years. These advances potentially provide a new avenue to study early human development. The benefits of SCEMs are predicated on the claim that they are different from embryos and should, therefore, be exempt from existing regulations that apply to embryos (such as the 14-day rule). SCEMs are proposed as offering a model that can capture the inner workings of the embryo but lack its moral sensitivities. However, the ethical basis for making this distinction has not been clearly explained. In this current controversy, we focus on the ethical justification for treating SCEMs differently to embryos, based on considerations of moral status. (shrink)

Although bone development during embryogenesis and bone repair after injury have a number of features which appear similar, they are distinctly different processes which involve separate controlling elements and cuing parameters. Repair of bone is influenced by bioactive factors which reside in bone itself; some of these factors are not present when embryonic mesenchymal cells first differentiate. For example, a bone protein which induces the conversion of mesenchymal cells into cartilage cells is not present in the embryo at (...) the site where cartilage first differentiates into the anlagen for future bone. Ultimately, the sequence of cellular and molecular events which controls the success of bone repair is dependent on the prior embryologic and developmental packaging of bioactive factors into bone and the release of these factors at a bone break site. The success of the reparative events depends not only upon the release of these bone‐derived factors but also on systemic factors and the identity and numbers of responding cells at the repair site. (shrink)

Advancement in science may represent a headway in procreation, but ethicists and theologians have anxieties about the future uses of such procreative technologies. The procreative advancement often involves the use of a human embryo. There is widespread moral and theological disarray concerning the use of embryos. The Hindu ethics presented in this chapter presumes the sanctity of human life of all sentient beings. The Hindu belief does not recognize that a human embryonic formation is an inconsequential and hence discardable (...) tissue, nor is it a developed adult being. Destroying an embryo is said to incur karmic consequences in Hindu thought. This being so, Hindu ethics would object to the creation of embryos and foetuses for the sole purpose of experimentation. The chapter focuses on the ramifications of Hindu ethics with respect to its application to interventionist or intrusive embryonic research and of debates thereto. (shrink)

The development of public policy on bioethical issues can be approached through substantive moral and philosophic reasoning, or through balancing perceived societal views as to what is ethically acceptable. The Human Embryo Research Panel had to apply the first approach to the question of the moral status of the preimplantation embryo. Only after concluding that the preimplantation embryo was not a full human subject could the panel consider the conditions under which embryo research was ethically (...) acceptable, given a range of societal views, concerns, and interests. (shrink)

The three cycles of cell division immediately following theformation of the cellular blastoderm during Drosophila embryogenesis display an invariant pattern(1,2). Bursts of transcription of a gene called string are required and sufficient to trigger mitosis at this time during development(3). The activator of mitosis encoded by the string gene is a positive regulator of cdc2 kinase and a Drosophila homologue of the Saccharomyces pombe cdc25 tyrosine phosphatase(4,5). Evidence presented in a recent paper(6) demonstrates that transcription of string, and hence (...) the timing and pattern of mitosis in the postblastoderm embryo, is under complex developmental control. Several lines of evidence support this interpretation, including the analysis of string transcription in pattern formation mutants, cell cycle arrest mutants, and the preliminary characterization of an extensive cis‐acting regulatory region. (shrink)

In this paper, we explore the recent creation of “iBlastoids,” which are 3-D structures that resemble early human embryos prior to implantation which formed via self-organization of reprogrammed ad...

Neither the George Washington University embryo splitting experiment nor the technique of embryo splitting itself has ethical flaws. The experiment harmed or wronged no one, and the investigators followed intramural review procedures for the experiment, although some might fault them for failing to seek extramural consultation or for not waiting until national guidelines for research on preembryos were developed. Ethical objections to such cloning on the basis of possible loss of individuality, possible lessening of individual worth, and concern (...) about potential harm to the resulting children are discussed and challenged, as are objections to the creation of embryos for the purpose of genetic diagnosis. Many of the ethical questions raised by the George Washington experiment are similar to those posed by existing reproductive technologies that allow the simultaneous production of several embryos. A multidisciplinary group should consider whether regulation of cloning is needed, and laws should be enacted to prohibit a commercial market for all frozen embryos. (shrink)

The relationship of embryonal carcinoma (EC) cells, the stem cells of germ cell‐ or embryo‐derived teratocarcinoma tumors, to early embryonic cells came under intense scrutiny in the early 1970s when mouse chimeras were produced between EC cells and embryos. These chimeras raised tantalizing possibilities and high hopes for different areas of research. The normalization of EC cells by the embryo lent validity to their use as in vitro models for embryogenesis and indicated that they might reveal information about (...) the relationship between malignancy and differentiation. Chimeras also showed the way for the potential introduction of genes, selected in EC cells in vitro, into the germ line of mice. Although EC cells provided material for the elucidation of early embryonic events and stimulated many studies of early molecular differentiation, after years of intense scrutiny, they fell short as the means of genetic manipulation of the germ line, although arguably they pointed the way to the development of embryonic stem (ES) cells that eventually fulfilled this goal. (shrink)

Human embryonic moral status in the embryo debate in the Indian religious school of thoughts is a challenging issue. The paper tries to figure out whether ontological status implies moral status of embryo. Consciousness is an important determinant of animation of human embryo. In this paper an attempt had been made to understand the concept of man and soul in the Hindu philosophical thought. In the process we would also make a critical review of embryology in the (...) Hindu philosophical thought. The study would adopt a conceptual elucidation of morality. The paper made an elaborative study of Puruṣa as found in the Saṃkhya Philosophy and the study of consciousness and animation would try to resolve the related question, when does life begin to have that value? Embryo-protectionist regards embryos as a potential person. The Gita says the human person is individual self-called āttmā, whose nature is of pure consciousness, Brahman/Puruṣa. Consciousness constitutes the essentiality of individual Self. Human embryo developments are elaborately studied in the Yajñavalkya Smṛti, Garbha Upaniṣad, and Suśruta Saṃhitā. The self that remain latent in the embryo gets impetus with the association of consciousness until then it cannot be a human personality. In Hinduism sanctity of life gets combined with autonomy and self-determination. The sanctity of life applies both to the fetus as well as to the overall welfare of the society. The embryo being in an interim stage and the soul not being destroyed upon body annihilation, it may be claimed that since destruction or annihilation of the physical form does not destroy the soul, beneficial embryo research should thus not be abhorrent. The Hindu ethics as examined here precludes the consideration of the situation at hand, and causing the least harm and work according to one’s dharma. (shrink)

Three basic political positions on embryo research will be identified as libertarian, conservative, and social-democratic. The Human Embryo Research Panel will be regarded as an expression of the social-democratic position. A taxonomy of the ethical issues addressed by the Panel will then be developed at the juncture of political and ethical modes of reflection. Among the arguments considered will be those for the separability of the abortion and embryo research debates; arguments against the possibility of the preembryo (...) being a person, especially arguments associated with totipotency and the significance of the primitive streak; and the various reasons for regulating embryo research, including those associated with respect for the preembryo, the protection of traditional views of human procreation, and the prevention of commercialization. (shrink)