In the field of germline development in amniote vertebrates, primordial germ cell (PGC) specification in birds and reptiles remains controversial. Avians are believed to adopt a predetermination or maternal specification mode of PGC formation, contrary to an inductive mode employed by mammals and, supposedly, reptiles. Here, we revisit and review some key aspects of PGC development that channelled the current subdivision, and challenge the position of birds and reptiles as well as the ‘binary’ evolutionary model of PGC development in vertebrates. (...) We propose an alternative view on PGC specification where germ plasm plays a role in laying the foundation for the formation of PGC precursors (pPGC), but not necessarily of PGCs. Moreover, inductive mechanisms may be necessary for the transition from pPGCs to PGCs. Within this framework, the implementation of data from birds and reptiles could provide new insights on the evolution of PGC specification in amniotes. (shrink)

Providing in-utero treatments to target specific conditions in the fetus is a relatively new approach in perinatal care, with the vast majority of these treatments being used off-label. The high degree of off-label medication use in the perinatal and neonatal settings raises concern for the safety of both the fetuses and expectant mothers. This report presents two examples of intra-amniotic drug administration based on reported clinical cases. From the ethical framework of medical principlism, we examine the competing ethical duties of (...) autonomy, beneficence, and non-maleficence in this setting. We then lay out three fundamental ethical principles for obtaining informed consent and maximizing clinical benefit. (shrink)

A rigorous cladistic analysis of the dorsal pallium of amniotes indicates that the stem amniote lacked sensorimotor areas. Reptiles apparently acquired a visual cortex by parcellation from the multimodal, hippocampal-like mediodorsal pallium of stem amniotes. The high number of sensory areas of the mammalian isocortex might derive from the specific properties it shows, such as growth-promoting influence on thalamic axons.

Frequent independent origins of environmental sex determination (ESD) are assumed within amniotes. However, the phylogenetic distribution of sex‐determining modes suggests that ESD is likely very ancient and may be homologous across ESD groups. Sex chromosomes are demonstrated to be old and stable in endothermic (mammals and birds) and many ectothermic (non‐avian reptiles) lineages, but they are mostly non‐homologous between individual amniote lineages. The phylogenetic pattern may be explained by ancestral ESD with multiple transitions to later evolutionary stable genotypic sex (...) determination. It is pointed out here that amniote ESD shares several key aspects with sequential hermaphroditism of fishes such as a lack of sex differences in genomes, biased population sex ratios, and potentially also molecular mechanism related to general stress responses. Here, it is speculated that ESD evolves via a heterochronic shift of the sensitive period of sex change from the adult to the embryonic stage in a hermaphroditic amniote ancestor. Also see the video abstract here https://youtu.be/q2mjtlCefu4. (shrink)

The dorsal and medial pallial formations of mammals, birds, and reptiles show overall functional striking similarities. Most of these similarities have been frequently considered examples of convergent evolution. However, a considerable amount of neurobiological comparative evidence suggests the presence of a common basic pattern of vertebrate forebrain organization. This common pattern can support functional conservation.

To answer the question of why we have consciousness, I propose the following evolutionary trajectory leading to this feature: Nervous systems appeared for the purpose of orchestrating behavior. As a rule of thumb the challenges facing an animal concern either approach or avoidance. These two options were originally hard-wired as reflexes. Improvements in adaptability of response came with an expansion of the computational aspect of the system and a concomitant shift from simple reflexes to instinctual behavior, learning, and eventually, feelings. (...) The assessment of positive and negative feelings allows organisms to weigh various options, but for this to be a viable strategy, an awareness of hedonic value is required. This was presumably the first neural attribute to evolve that required awareness, and thus the key force in the evolution of consciousness. The attribute first appeared in the early amniotes (the phylogenetic group comprising reptiles, birds and mammals). Support for this model in current accounts of the neurobiology of feelings and consciousness is discussed. (shrink)

A ubiquitous feature of the auditory organ in amniotes is the longitudinal mapping of neuronal characteristic frequencies (CFs), which increase exponentially with distance along the organ. The exponential tonotopic map reflects variation in hair cell properties according to cochlear location and is thought to stem from concentration gradients in diffusible morphogenic proteins during embryonic development. While in all amniotes the spatial gradient is initiated by sonic hedgehog (SHH), released from the notochord and floorplate, subsequent molecular pathways are not (...) fully understood. In chickens, BMP7 is one such morphogen, secreted from the distal end of the cochlea. In mammals, the developmental mechanism differs from birds and may depend on cochlear location. A consequence of exponential maps is that each octave occupies an equal distance on the cochlea, a spacing preserved in the tonotopic maps in higher auditory brain regions. This may facilitate frequency analysis and recognition of acoustic sequences. (shrink)

Holobionts are multicellular eukaryotes with multiple species of persistent symbionts. They are not individuals in the genetic sense— composed of and regulated by the same genome—but they are anatomical, physiological, developmental, immunological, and evolutionary units, evolved from a shared relationship between different species. We argue that many of the interactions between human and microbiota symbionts and the reproductive process of a new holobiont are best understood as instances of reciprocal scaffolding of developmental processes and mutual construction of developmental, ecological, and (...) evolutionary niches. Our examples show that mother, fetus, and different symbiotic microbial communities induce or constitute conditions for the development and reproduction of one another. These include the direct induction of maternal or fetus physiological changes, the restructuring of ecological relations between communities, and evolutionary selection against undesirable competitors. The mutual scaffolding and niche constructing processes start early—prior to amniotic rupture. We are evolutionarily, physiologically, and developmentally integrated holobiont systems, strung together through mutual reliance and mutual construction. Bringing the processes of niche construction and developmental scaffolding together to interpret holobiont birth conceptually scaffolds two new directions for research: in niche construction, identifying the evolutionary implications of organisms actively constructing multiple overlapping niches and scaffolds, and in Evolutionary Developmental Biology, characterizing evolutionary and ecological processes as developmental causes. (shrink)

Preterm birth is defined as delivery occurring before 37 weeks gestation.1 Infants born prematurely have increased risks of morbidity and mortality throughout life, especially during the first year. These risks increase as the gestational age at birth decreases.2 Additionally, there are significant racial and ethnic differences in preterm birth rates. In 2022, the rate of preterm birth among non-Hispanic black women was approximately 50% higher than that observed in non-Hispanic white women.1 The outcomes for these infants are also disparate–preterm birth (...) and low birth weight are the second-leading causes of infant mortality (deaths before 1 year of age). Notably, among preterm neonates, infants born to non-Hispanic black women have a mortality rate more than double that of infants born to non-Hispanic white mothers.3 Importantly, there is a small but significant group of neonates that can be classified as severely premature (those born <28 weeks). Infants born before 28 weeks have varied and uncertain outcomes. While this group accounts for only 0.4% of preterm births, it also accounts for 40% of deaths among preterm neonates.4 As noted by Romanis and Adkins, the advent of artificial amnion and placenta technology (AAPT) holds promise for its potential to address the physiologic complications and mortality risks of extreme prematurity by introducing amniotic substitutes that mimic in vivo placental oxygenation and substrate delivery. In contrast …. (shrink)

Turtles are among the most intriguing amniotes but their communication and signaling have rarely been studied. Traditionally, they have been seen as basically just silent armored ‘walking stones’ with complex physiology but no altruism, maternal care, or aesthetic perception. Recently, however, we have witnessed a radical change in the perception of turtle behavioral and cognitive skills. In our study, we start by reviewing some recent findings pertaining to various highly developed behavioral and cognitive patterns with special emphasis on turtles. (...) Then we focus on freshwater turtles and use data about their sexual behavior and size sexual dimorphism to test whether conspicuous coloration of the head is in these animals related to sexual processes. We found that absence of aggressive mating behavior is statistically associated with the presence of conspicuous coloration on turtles’ heads. It also seems that while species with female-biased SSD are characterised by conspicuously colored head ornaments, in species with male-biased SSD conspicuous coloration is absent. Unlike large females, males thus seem to be under pressure to develop conspicuous coloration and engage in non-aggressive behavior using signaling to succeed in courtship. And finally, we discuss possible roles of head color patterns in turtle communication during mating. (shrink)

The main objective of this essay is to validate some of the principal, currently competing, mammalian consciousness-brain theories by comparing these theories with data on both cognitive abilities and brain organization in birds. Our argument is that, given that multiple complex cognitive functions are correlated with presumed consciousness in mammals, this correlation holds for birds as well. Thus, the neuroanatomical features of the forebrain common to both birds and mammals may be those that are crucial to the generation of both (...) complex cognition and consciousness. The general conclusion is that most of the consciousness-brain theories appear to be valid for the avian brain. Even though some specific homologies are unresolved, most of the critical structures presumed necessary for consciousness in mammalian brains have clear homologues in avian brains. Furthermore, considering the fact that the reptile-bird brain transition shows more structural continuity than the stem amniote-mammalian transition, the line drawn at the origin of mammals for consciousness by several of the theorists seems questionable. An equally important point is that consciousness cannot be ruled out in the absence of complex cognition; it may in fact be the case that consciousness is a necessary prerequisite for complex cognition. (shrink)

Beginning by reading a 1992 feminist appropriation of Michelangelo's Creation of Adam – in a cartoon in which the finger of a nude Adamic woman touches a computer keyboard, while the god-like VDT screen shows a disembodied fetus – ‘Virtual Speculum’ argues for a broader conception of ‘new reproductive technologies’ in order to foreground justice and freedom projects for differently situated women in the New World Order. Broadly conceptualized reproductive practices must be central to social theory in general, and to (...) technoscience studies in particular. Tying together the politics of self help and women's health movements in the United States in the 1970s with positions on reproductive freedom articulated within the Legal Defense and Educational Fund of the NAACP in the 1990s, the paper examines recent work in feminist science studies in several disciplinary and activist locations. Statistical analysis and ethnography emerge as critical feminist technologies for producing convincing representations of the reproduction of inequality. Untangling the semiotic and political–economic dialectics of invisibility and hypervisibility, ‘Virtual Speculum’ concludes by linking the well-surveyed amniotic fluid of on-screen fetuses and the off-frame diarrhea of uncounted and underfed infants in regimes of flexible accumulation and structural adjustment. (shrink)

Postnatal parent-infant physiological regulatory effects described in the previous paper (Part I) are viewed here as being biologically contiguous with events that occur prenatally, preparing and sensitizing the fetus to the average microenvironment into which the infant is expected, based on its evolutionary past, to be born. Following McKenna (1986), evidence (some of which is circumstantial) is presented concerning fetal hearing and fetal amniotic liquid breathing as they are affected both by maternal cardiovascular blood flow sounds in the uterus and (...) by fluctuating maternal blood sugar levels. These data are linked in turn to the infant’s postulated postnatal responsivity to parental sensory cues, including auditory and vestibular respiratory cues that may assist infants as they “learn” to breathe and, for some, to resist a SIDS event. Data on the respiratory and vocalizing behavior of normal and hearing-impaired persons are used to show that not all forms of human breathing are innate; some forms develop with experience. These data reveal how human infants learn, for example, to coordinate higher and lower brain respiratory nuclei in the context of learning initially to cry with intent and purpose and later to speak. Voluntary, cortex-based breathing emerges at the same time that infants are most likely to die from SIDS, between 2 and 4 months of age. This switch between voluntary and involuntary breathing during both sleep (while dreaming) and wake cycles, which depends on the integration of higher cortical and lower brain stem nuclei, is complex and is possibly the basis of the human species’ unique susceptibility to SIDS—a syndrome as yet unrecognized in other species. These human infant vulnerabilities, including delayed maturity, can explain in part why natural selection ought to favor increased infant sensitivity to parental sensory cues provided by a caregiver—stimuli available in the evolving parental care environment that included parent-infant co-sleeping for more than 4–5 million years of human evolution. (shrink)

The isocortex is a distinctive feature of mammalian brains, which has no clear counterpart in the cerebral hemispheres of other amniotes. This paper speculates on the evolutionary processes giving rise to the isocortex. As a first step, we intend to identify what structure may be ancestral to the isocortex in the reptilian brain. Then, it is necessary to account for the transformations (developmental, connectional, and functional) of this ancestral structure, which resulted in the origin of the isocortex. One long-held (...) perspective argues that part of the isocortex derives from the ventral pallium of reptiles, whereas another view proposes that the isocortex originated mostly from the dorsal pallium. We consider that, at this point, evidence tends to favor correspondence of the isocortex with the dorsal cortex of reptiles. In any case, the isocortex may have originated partly as a consequence of an overall “dorsalizing” effect (that is, an expansion of the territories expressing dorsal-specific genes) during pallial development. Furthermore, expansion of the dorsal pallium may have been driven by selective pressures favoring the development of associative networks between the dorsal cortex, the olfactory cortex, and the hippocampus, which participated in spatial or episodic memory in the early mammals. In this context, sensory projections that in reptiles end in the ventral pallium, are observed to terminate in the isocortex (dorsal pallium) of mammals, perhaps owing to their participation in these associative networks. Key Words: basolateral amygdala; claustrum; Emx-1; endopiriform nucleus; dorsal cortex; dorsal ventricular ridge; hippocampus; homology; olfactory cortex; Pax-6; ventral pallium. (shrink)

Retinoids play a critical role in patterning, segmentation, and neurogenesis of the posterior hindbrain and it has been proposed that they act as a posteriorising signal during hindbrain development. Until now, direct evidence that endogenous retinoid signalling acts through a gradient to specify cell fates along the anteroposterior axis has been missing. Two recent studies tested the requirement for retinoid signalling in the developing hindbrain through systematic application of a pan-retinoic acid receptor antagonist.(1,2) They demonstrate a stage-dependent requirement for increasing (...) retinoid signalling activity along the hindbrain that proceeds from anterior to posterior. Together these findings challenge the concept of a stable gradient of retinoic acid across the hindbrain and warrant a re-interpretation of the phenotypes obtained by genetic and nutritional disruption of retinoid signalling in the amniote embryo. BioEssays 23:981–986, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

The evolutionary history of muscle development in the paired fins of teleost fish and the limbs of tetrapod vertebrates is still, to a large extent, uncertain. There has been a consensus, however, that in the vertebrate clade the ancestral mechanism of fin and limb muscle development involves the extension of epithelial tissues from the somite into the fin/limb bud. This mechanism has been documented in chondrichthyan, dipnoan, chondrostean and teleost fishes. It has also been assumed that in amniotes, in (...) contrast, individual progenitor cells of muscles migrate from the somites into the limb buds. Neyt et al.(1) now present the exciting finding that in zebrafishes this presumably derived mechanism involving individual cell migration, is present. They conclude, based on data on sharks, zebrafishes, chickens, quails and mice that the derived mechanism was present in the sarcopterygians. This conclusion, however, may be premature in the light of further data available in the literature, which show a highly mosaic distribution of this character in the vertebrate clade. Furthermore, a developmental mode exists that is intermediate between the supposed ancestral and derived modes in teleosts, reptiles and possibly amphibians. BioEssays 23:383–387, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Bibliography of Resources by and about André E. Hellegers*Compiled by Doris Mueller Goldstein (bio)This bibliography is derived from the holdings of the National Reference Center for Bioethics Literature and the BIOETHICSLINE© database (both of which are at the Kennedy Institute of Ethics and supported by the National Library of Medicine); the archives of Lauinger Library, Georgetown University; the Medline databases of the National Library of Medicine; the WorldCat database (...) of OCLC, Dublin, Ohio, and selected Internet sites.Primarily comprised of writings by Dr. Hellegers, the list also includes interviews and media programs in which he participated, as well as writings about him that were written following his death. The arrangement within each section is by date. The 231 authored pieces reflect the transition from Dr. Hellegers’s early career as a researcher in fetal physiology at Johns Hopkins Medical School, where he published his first research report at the age of 29, to the early years of the Kennedy Institute, where he produced so many provocative columns on bioethical issues that influenced the growth of the field.Due to the diversity of sources and the 40-year time span covered, there are some variations in bibliographic style. Time and availability constraints precluded verifying all of the citations with the original documents. Any additions or corrections should be submitted to the compiler.Works Authored by André E. HellegersNo Date Ethical Issues in Sterilization of the Retarded. Unpublished paper.1956Vitamin B12 Serum Level and Pregnancy. American Journal of Clinical Nutrition 4: 440+, 1956. [With Bacon F. Chow and Kunio Okuda] [End Page 89]1957Vitamin B12 Absorption in Pregnancy and in the Newborn. American Journal of Clinical Nutrition 5: 327+, 1957. [With Bacon F. Chow, Robert E. L. Nesbitt, Kunio Okuda, and David W. Smith]1958The Effects of Acute Hypoxia on the Osmotic Pressure of the Plasma. Quarterly Journal of Experimental Physiology 43: 197+, 1958. [With Donald H. Barron, Frederick C. Battaglia, and Giacomo Meschia]Studies on the Absorption of Vitamin B12 in Human Pregnancy with Especial Reference to the Effect of D-Sorbitol. American Journal of Obstetrics and Gynecology 76: 91+, 1958. [With Bacon F. Chow, Harry Prystowsky, and Vernon Wong]1959The Alveolar PCO2 and PO2 in Pregnant and Nonpregnant Women at Altitude. Proceedings of the Society for Clinical Investigation 38: 1010+, 1959. [With Donald Barron, William Huckabee, Giacomo Meschia, James Metcalfe, and Harry Prystowsky]A Comparison of the Oxygen Dissociation Curves of the Bloods of Maternal and Fetal Goats at Various pHs. Quarterly Journal of Experimental Physiology 44: 215–21, July 1959. [With Donald Barron, Giacomo Meschia, Harry Prystowsky, and A. Stark Wolkoff]Fetal Blood Studies. XII. On the Relationship Between the Position of the Oxygen Dissociation Curve of Human Fetal Blood and Adult Fetal Hemoglobin. American Journal of Obstetrics and Gynecology 77: 585+, 1959. [With Paul D. Bruns, Julian Cotter, and Harry Prystowsky]Fetal Blood Studies. XIV. A Comparative Study of the Oxygen Dissociation Curve of Nonpregnant, Pregnant and Fetal Human Blood. American Journal of Obstetrics and Gynecology 78: 489–93, September 1959. [With Paul D. Bruns and Harry Prystowsky]Fetal Blood Studies. XVI. On the Changes in Total Osmotic Pressure and Sodium and Potassium Concentration of Amniotic Fluid During the Course of Human Gestation. Surgery, Gynecology and Obstetrics 109: 509–12, October 1959. [With Frederick Battaglia, Paul D. Bruns, Harry Prystowsky, and Clayton Smisson]Further Observations on the Metabolism of Vitamin B12 in Human Pregnancy. American Journal of Obstetrics and Gynecology 77: 1+, 1959. [With Bacon F. Chow, Harry Prystowsky, Bruno Ranke, and Elma Ranke]The Oxygen Dissociation Curves of the Bloods of Adult and Fetal Llamas. Federation Proceedings 18, 1959. [With Donald Barron, William Huckabee, Giacomo Meschia, James Metcalfe, and Harry Prystowsky] [End Page 90]Transfer of Oxygen Across the Sheep Placenta at High Altitude. Federation Proceedings 18, 1959. [With Donald Barron, William Huckabee, Giacomo Meschia, and Harry Prystowsky]Uterine Blood Flow and Metabolism in Pregnant Sheep at High Altitude. Federation Proceedings 18, 1959. [With Donald Barron, William Huckabee, Giacomo Meschia, James Metcalfe, and Harry Prystowsky]Uterine Blood Flow and Metabolism in Unanesthetized Pregnant Sheep. Federation Proceedings 18, 1959. [With Donald Barron, William Huckabee, Giacomo... (shrink)

This paper describes a new course in Medical Technology and Critical Decisions, part of the Technology Studies Program at Wellesley College, established with the support of the Alfred P. Sloan Foundation's New Liberal Arts Program. The course uses the dramatic new options in medicine presented by technology to individuals and society as a vehicle for promoting general technological literacy in liberal arts students. The course motivates the study of the scientific principles on which the technology rests and the mathematical principles (...) of a methodology for making rational choices. A case in point is the decision of a pregnant woman whether or not to undergo amniocentesis, a procedure used to determine the genetic make-up of a fetus from cells in the amniotic fluid. The course introduces students to the underlying notions of genetics; the physical principles behind the ultrasound imaging technique used to position the needle that draws the fluid; the probability and statistics needed to understand the risks to the woman and fetus both of having and of not having the procedure; and the methodology of decision analysis, increasingly used by genetic counselors to help prospective parents incorporate their personal values into the decision-making process. (shrink)

Conversing happily with my son we had been driving home when my mobile phone rang. Startled at the sound of my obstetrician's voice I had pulled off to the side of the road. At 18 weeks gestation I was told in a factual tone that the results from my serum screen had come back, indicating that our baby was at increased risk of Trisomy 18. Gripping the steering wheel my head had spun as he talked, explaining that Trisomy 18 was (...) worse than Trisomy 21 because our baby was not going to live. We had been thrilled when we heard the news of my pregnancy but now my temples throbbed and tears brimmed in my eyes. Suddenly my world was turned upside down and it had felt like someone reached into my chest and ripped my heart out.My husband and I decided that an amniocentesis was needed for a positive diagnosis and this was arranged for the following day. Studiously the sonographer performed the diagnostic ultrasound with a furrow across his brow. Watching the monitor I saw my baby moving as I watched the colours of red and blue flow through the heart and heard the regular, fast rhythm of the heartbeat. Quietly I hoped that the news was good but the creased brow had told me otherwise. Holding the amniotic fluid in his right hand the sonographer had glanced from it to me and empathetically informed me that the news wasn't good and that he didn't need to send the sample off for a positive diagnosis. Once again my world was crashing and all I wanted to do was bury my head in a pillow and sob. The following weekend dragged and had been filled with streams of tears and emotional turmoil. All I wanted to …. (shrink)

Bridging feminist new materialism and feminist phenomenology, Astrida Neimanis’s volume, Bodies of Water, discusses water in terms of nurturing maternality based on a figural reservoir of what she terms “amniotics” and “planetary breastmilk” in order to posit this maternality as the material condition of the embodiment of life. In this article I show that this imagery is a construction consistently haunted by figures of anxiety and loss. I do this by first revisiting earlier interventions in deconstruction concerning materiality and feminist (...) theory as follows. First, pointing out a resonance between this figuration of wateriness and Kant’s notion of the dynamic sublime, I turn to Paul de Man’s reading of materiality in the Kantian sublime in order to suggest that Neimanis’s figuration of maternal water is an effect of an aesthetic ideology. Subsequently, I will revisit Diana Fuss’s reading of Irigaray – Neimanis’s main feminist resource – to show that the ontological status of water as maternal is constructed via an Irigarayan distinction between metaphor and metonymy. Finally, in order to show ways in which the maternal materiality of water is haunted by figures of anxiety and loss, I will consult Elissa Marder’s more recent work on the maternal function. (shrink)

The primitive streak establishes the antero‐posterior body axis in all amniote species. It is thought to be the conduit through which mesoderm and endoderm progenitors ingress and migrate to their ultimate destinations. Despite its importance, the streak remains poorly defined and one of the most enigmatic structures of the animal kingdom. In particular, the posterior end of the primitive streak has not been satisfactorily identified in any species. Unexpectedly, and contrary to prevailing notions, recent evidence suggests that the murine posterior (...) primitive streak extends beyond the embryo proper. In its extraembryonic site, the streak creates a node‐like cell reservoir from which the allantois, a universal caudal appendage of all amniotes and the future umbilical cord of placental mammals, emerges. This new insight into the fetal/umbilical relationship may explain the etiology of a large number of umbilical‐associated birth defects, many of which are correlated with abnormalities of the embryonic midline. (shrink)

FOREWORD. Gilbert Gottlieb and the Developmental Point of View. I. INTRODUCTION. 1. Developmental Systems, Nature-Nurture, and the Role of Genes in Behavior and Development: On the Legacy of Gilbert Gottlieb. 2. Normally Occurring Environmental and Behavioral Influences on Gene Activity: From Central Dogma to Probabilistic Epigenesis. II. THEORETICAL FOUNDATIONS FOR THE DEVELOPMENTAL STUDY OF BEHAVIOR AND GENETICS. 3. Historical and Philosophical Perspectives on Behavioral Genetics and Developmental Science. 4. Development and Evolution Revisited. 5. Probabilistic Epigenesis and Modern Behavioral and Neural (...) Genetics. 6. The Roles of Environment, Experience, and Learning in Behavioral Development. 7. Contemporary Ideas in Physics and Biology in Gottlieb’s Psychology. III. EMPIRICAL STUDIES OF BEHAVIORAL DEVELOPMENT AND GENETICS. 8. Behavioral Development during the Mother-Young Interaction in Placental Mammals: The Development of Behavior in the Relationship with the Mother. 9. Amniotic Fluid as an Extended Milieu Interieur. 10. Developmental Effects of Selective Breeding for an Infant Trait. 11. Emergence and Constraint in Novel Behavioral Adaptations. 12. Nonhuman Primate Research Contributions to Understanding Genetic and Environmental Influences on Phenotypic Outcomes across Development. 13. Interactive Contributions of Genes and Early Experience to Behavioural Development: Sensitive Periods and Lateralized Brain and Behaviour. 14. Trans-Generational Epigenetic Inheritance. 15. The Significance of Non-Replication of Gene-Phenotype Associations. 16. Canalization and Malleability Reconsidered: The Developmental Basis of Phenotypic Stability and Variability. IV. APPLICATIONS TO DEVELOPMENT. 17. Gene-Parenting Interplay in the Development of Infant Emotionality. 18. Genetic Research in Psychiatry and Psychology: A Critical Overview. 19. On the Limits of Standard Quantitative Genetic Modeling of Inter-Individual Variation: Extensions, Ergodic Conditions and a New Genetic Factor Model of Intra-Individual Variation. 20. Songs My Mother Taught Me: Gene-Environment Interactions, Brain Development and the Auditory System: Thoughts on Non-Kin Rejection, Part II. 21. Applications of Developmental Systems Theory to Benefit Human Development: On the Contributions of Gilbert Gottlieb to Individuals, Families, and Communities. (shrink)

The position that Aboitiz et al. have taken on the regions of the stem amniote brain from which neocortex arose, and on homologies among telencephalic pallial regions in mammals and sauropsids, is premature. Nonetheless, if their intent is to promote thought, discussion, and experimentation on this important topic, then their paper is valuable.

Graphical AbstractIn article number 2000050, Barbora Straková et al. speculate that environmental sex determination in amniotes evolves via a heterochronic shift of sex change from the adult to the embryonic stage in a hermaphroditic ancestor. Subsequently, the loss of responsiveness to environmental stimuli (stress) led to genotypic sex determination, where the sex is decided at conception. Cover image by Tereza Unzeitigova.

In lieu of an abstract, here is a brief excerpt of the content:Genetic Testing and Genetic ScreeningPat Milmoe McCarrick (bio)In recent years there has been an enormous expansion in the knowledge that may be gleaned from the testing of an individual's genetic material to predict present or future disability or disease either for oneself or one's offspring. The Human Genome Project, which is currently mapping the entire human gene system, is identifying progressively more genetic sequencing information (see Scope Note 17, (...) The Human Genome Project). Information obtained from genetic testing raises ethical and legal questions about its uses by society. The ethical dilemmas were foreseen two decades ago by bioethicists who asked whether questionable applications could stop "legitimate pursuits" (IV, Gaylin 1972) and whether genetic disease might come to be viewed as "transmissible" in the sense of being contagious (IV, Veatch 1974).Not only has knowledge expanded, but the practice of genetic testing and screening has greatly increased as well. For example, in the case of testing for cystic fibrosis (CF), the U.S. Congress' Office of Technology Assessment (OTA) estimates that instances of screening jumped from 9310 tests in 1991 to 63,000 tests in 1992 (I, OTA [Cystic Fibrosis] 1992). In addition, the OTA estimates that within the next few years, the six million women who become pregnant each year routinely will be informed of available CF carrier tests (I, OTA [Cystic Fibrosis] 1992).Following the recent identification of a gene linked to breast cancer, Dr. Francis Sellers Collins, director of the National Center for Human Genome Research, said that "it is not inconceivable that every woman in America may want to be screened for this gene. The economic, ethical, and counseling issues will be very daunting." Dr. Collins opines that in the near future physical examinations for 18-year-olds will include DNA testing for diseases with genetic components and that physicians, in the interests of preventive medicine, will make risk-based recommendations for a healthy life-style (IV, Breo 1993). The U.S. President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research predicted as early as 1983 that before the end of the century genetic screening and counseling would become major components of both public health and individual medical care (I, U.S. President's Commission 1983). [End Page 333]The OTA defines genetic testing as "the use of specific assays to determine the genetic status of individuals already suspected to be at high risk for a particular inherited condition. The terms genetic test, genetic assay, and genetic analysis are used interchangeably to mean the actual laboratory examination of samples." In contrast, genetic screening usually uses the same assays employed for genetic testing but is distinguished from genetic testing by its target population (I, OTA [Genetic Monitoring] 1990). The National Academy of Sciences (NAS) defines screening as the systematic search of populations for persons with latent, early, or asymptomatic disease (III, NAS 1975). Some of the literature annotated for this Scope Note appears to use the terms "testing" and "screening" interchangeably.Philip Boyle of the Hastings Center points out that the language used to describe genetic variation is important and asks what words should be used: "Defects, flaws, deleterious genes, disorders, or the more neutral conditions? Using words such as normal—and its corollary, abnormal—is likely to foster stigmatization and discrimination" (III, Genetic Grammar, Boyle 1992).Areas of focus in genetic testing include: prenatal diagnosis, newborn screening, carrier screening, forensic screening, and susceptibility screening.Prenatal diagnosis discerns whether a fetus is at risk for various identifiable genetic diseases or traits. Prenatal diagnosis is made using amniotic fluid, fetal cells, and fetal or maternal blood cells obtained during amniocentesis testing; alpha fetoprotein assays or chorionic villus sampling; or ultrasound tomography, which creates fetal images on a screen. Another method, known as fetoscopy, uses a camera on a needle inserted in the uterus to view the fetus. Since prenatal screening began in 1966 (I, U.S. President's Commission 1983), the number of metabolic defects and genetic disorders that can be diagnosed prenatally has expanded greatly. There is also discussion of requiring testing for parents who are participating in an in vitro fertilization program and are at genetic... (shrink)

Graphical AbstractEnvironmental oxygen might have been the key for the evolution of novel developmental mechanisms, such as the interdigital cell death of amniotes. Increased amount of oxygen can also induce cell death in interdigital regions of an amphibian that typically lacks it. To learn more about the role of environmental oxygen in the evolution of new traits, see the article number 2000025 by Ingrid Rosenburg Cordeiro and Mikiko Tanaka. Cover image by Itoko Tanaka and Mikiko Tanaka.

Oxygen is a key regulator of both development and homeostasis and a promising candidate to bridge the influence of the environment and the evolution of new traits. To clarify the various ways in which oxygen may modulate embryogenesis, its effects are reviewed at distinct organizational levels. First, the role of pathways that sense dioxygen levels and reactive oxygen species are reviewed. Then, the effects of microenvironmental oxygen on metabolism, stemness, and differentiation throughout embryogenesis are discussed. Last, the interplay between ecology (...) and development are reexamined with a focus on the evolution of tetrapods, including during the emergence of a novel mechanism that shapes amniote limbs—interdigital cell death. Both genetic and environmental components work together during the formation of organisms, highlighting the importance of a multidisciplinary approach for understanding the evolution of new traits. (shrink)

We hypothesize that threat of dehydration provided selection pressure for the evolutionary emergence and persistence of the anterior communicating artery (ACoA – the inter‐arterial connection that completes the Circle of Willis) in early amniotes.The ACoA is a hemodynamically insignificant artery, but, as we argue in this paper, its privileged position outside the blood‐brain barrier gives it a crucial sensing function for the osmolarity of the blood against the background of the rest of the brain, which efficiently protects itself from (...) dehydration. Till now, the questions of why the ACoA evolved, and what its physiological function is, have remained unsatisfactorily answered. The traditional view—that the ACoA serves as a collateral source of vascularization in case of arterial stenosis—is anthropocentric, and not in accordance with principles of natural selection that apply more generally. Diseases underlying arterial stenosis are associated with aging and the human lifestyle, so this cannot explain why the ACoA formed hundreds of millions of years ago and persisted in amniotes to this day.The peculiar hemodynamic properties of the ACoA could be selected traits that allowed for more efficient forebrain detection of dehydration and complex behavioral responses to water loss, a major advantage in the survival of early amniotes. This hypothesis also explains insufficient hydration often seen in elderly humans. (shrink)

We hypothesize that threat of dehydration provided selection pressure for the evolutionary emergence and persistence of the anterior communicating artery (ACoA – the inter‐arterial connection that completes the Circle of Willis) in early amniotes.The ACoA is a hemodynamically insignificant artery, but, as we argue in this paper, its privileged position outside the blood‐brain barrier gives it a crucial sensing function for the osmolarity of the blood against the background of the rest of the brain, which efficiently protects itself from (...) dehydration. Till now, the questions of why the ACoA evolved, and what its physiological function is, have remained unsatisfactorily answered. The traditional view—that the ACoA serves as a collateral source of vascularization in case of arterial stenosis—is anthropocentric, and not in accordance with principles of natural selection that apply more generally. Diseases underlying arterial stenosis are associated with aging and the human lifestyle, so this cannot explain why the ACoA formed hundreds of millions of years ago and persisted in amniotes to this day.The peculiar hemodynamic properties of the ACoA could be selected traits that allowed for more efficient forebrain detection of dehydration and complex behavioral responses to water loss, a major advantage in the survival of early amniotes. This hypothesis also explains insufficient hydration often seen in elderly humans. (shrink)

Novel therapies resulting from regenerative medicine and tissue engineering technology may offer new hope for patients with injuries, end-stage organ failure, degenerative disorders and many other clinical issues. Currently, patients suffering from diseased and injured organs are treated with transplanted organs. However, there is a shortage of donor organs that is worsening yearly as the population ages and new cases of organ failure increase. Scientists in the field of regenerative medicine and tissue engineering are now applying the principles of cell (...) transplantation, material science, and bioengineering to construct biological substitutes that can restore and maintain normal function in diseased and injured tissues. In addition, the stem cell field is a rapidly advancing part of regenerative medicine, and new discoveries in this field create new options for this type of therapy. For example, new types of stem cells, such as amniotic fluid and placental stem cells, that can circumvent the ethical issues associated with embryonic stem cells have been discovered. The process of somatic cell nuclear transfer and the creation of induced pluripotent cells provide still other potential sources of stem cells for cell-based tissue engineering applications. While stem cells are still in the research phase, some therapies arising from tissue engineering endeavors that make use of autologous, adult cells have already entered the clinical setting, indicating that regenerative medicine holds much promise for the future. (shrink)