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The objective of the study is to primarily highlight the consistency between the embryologist and the histopathologist in microdissection testicular sperm extraction and to explore the factors affecting sperm retrieval. The research included 91 patients, aged 20 to 47, who visited our Reproductive Technology center from July 2020 to June 2023. Patient data were collected retrospectively, including demographics, physical exams, lab tests, radiological assessments, genetic analyses, medical histories and histopathological results. Using the Johnsen scoring system for evaluation, the histopathologist identified mature spermatozoa in the specimen in some patients (Johnsen score 8-10); however, the embryologist only declared successful sperm retrieval in 66.6% of them. Overall sperm retrieval rates were lower than expected at 40%. Significant factors influencing sperm retrieval rates included Follicle Stimulating Hormone ( p = 0.001), Luteinizing Hormone ( p = 0.007), testicular volume ( p < 0.001), histopathology ( p < 0.001), and alcohol consumption ( p = 0.007). A logistic regression model was used to identify the independent predictors of successful sperm retrieval. FSH ( p = 0.038), testicular volume ( p < 0.001), histopathology ( p < 0.001), and alcohol consumption ( p = 0.013) emerged as significant predictive factors for the outcome of sperm retrieval. As a result, in addition to patient-related factors, the consistency between the pathologist and embryologist also affects sperm retrieval rates., Competing Interests: The authors declare no conflict of interest., (©2024 The Author(s). Published by MRE Press.)

The discovery of the amphibian gastrula organizer and its publication by Hans Spemann and Hilde Mangold in 1924 is a foundation of experimental embryology, and has shaped our understanding of embryonic induction and pattern formation in vertebrates until today. The original publication is a piece of scientific art, characterized by the meticulous hand drawings by Hilde Mangold, as well as the text that develops mechanistic concepts of modern embryology. While historic microphotographs of specimens got lost, the original microscope slides and Hilde Mangold's laboratory notebook have been secured in embryological collections until today. Here, we make the original data of the six embryonic specimens reported in 1924, as well as the laboratory notebook, available in an accessible digital format. Together, these data shed light on the scientific process that led to the discovery, and should help to make the experiments on the most important signalling center in early vertebrate development transparent for generations of embryologists to come., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Organizing centers secrete morphogens that specify the emergence of germ layers and the establishment of the body's axes during embryogenesis. While traditional experimental embryology tools have been instrumental in dissecting the molecular aspects of organizers in model systems, they are impractical in human in-vitro model systems to dissect the relationships between signaling and fate along embryonic coordinates. To systematically study human embryonic organizer centers, we devised a collection of optogenetic ePiggyBac vectors to express a photoactivatable Cre-loxP recombinase, that allows the systematic induction of organizer structures by shining blue-light on human embryonic stem cells (hESCs). We used a light stimulus to geometrically confine SHH expression in neuralizing hESCs. This led to the self-organization of mediolateral neural patterns. scRNA-seq analysis established that these structures represent the dorsal-ventral forebrain, at the end of the first month of development. Here, we show that morphogen light-stimulation is a scalable tool that induces self-organizing centers., (© 2021. The Author(s).)

The current protocols of in vitro fertilization and culture in sheep rely on paradigms established more than 25 years ago, where Metaphase II oocytes are co-incubated with capacitated spermatozoa overnight. While this approach maximizes the number of fertilized oocytes, on the other side it exposes them to high concentration of reactive oxygen species (ROS) generated by active and degenerating spermatozoa, and positively correlates with polyspermy. Here we set up to precisely define the time frame during which spermatozoa effectively penetrates and fertilizes the oocyte, in order to drastically reduce spermatozoa-oocyte interaction. To do that, in vitro matured sheep oocytes co-incubated with spermatozoa in IVF medium were sampled every 30 min (start of incubation time 0) to verify the presence of a fertilizing spermatozoon. Having defined the fertilization time frame (4 h, data from 105 oocytes), we next compared the standard IVF procedures overnight (about 16 h spermatozoa/oocyte exposure, group o/nIVF) with a short one (4 h, group shIVF). A lower polyspermic fertilization (> 2PN) was detected in shIVF (6.5%) compared to o/nIVF (17.8%), P < 0.05. The o/nIVF group resulted in a significantly lower 2-cell stage embryos, than shIVF [34.6% (81/234) vs 50.6% (122/241) respectively, P < 0.001]. Likewise, the development to blastocyst stage confirmed a better quality [29% (70/241) vs 23.5% (55/234), shIVF vs o/nIVF respectively] and an increased Total Cell Number (TCN) in shIVF embryos, compared with o/n ones. The data on ROS have confirmed that its generation is IVF time-dependent, with high levels in the o/nIVF group. Overall, the data suggest that a shorter oocyte-spermatozoa incubation results in an improved embryo production and a better embryo quality, very likely as a consequence of a shorter exposure to the free oxygen radicals and the ensuing oxidative stress imposed by overnight culture., (© 2021. The Author(s).)

The Canal of Nuck (CN) is an anatomical structure which is often forgotten. It is the female equivalent of the male processus vaginalis and corresponds to a protrusion of parietal peritoneum that extends from the inguinal canal to labia majora. Radiologists rarely encounter patients with pathology of CN, especially in adult population. It is well known that CN diseases can occur in paediatric patient (especially younger than 5 years of age) and they are associated to high morbidity (for example ovarian hernia with high risk of incarceration and torsion). The aim of our work is to review embryology, anatomy and pathologies of the CN thanks to a multi modal approach-ultrasound (US), Computed Tomography (CT) and Magnetic Resonance imaging (MRI)-to make radiologists more aware of such conditions and guarantee a prompt and correct diagnosis not only in paediatric patients but also in the adult population.

The pros and cons of artificial intelligence in assisted reproductive technology are presented., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Pluripotent stem cells, in the recent years, have been demonstrated to mimic different aspects of metazoan embryonic development in vitro. This has led to the establishment of synthetic embryology: a field that makes use of in vitro stem cell models to investigate developmental processes that would be otherwise inaccessible in vivo. Currently, a plethora of engineering-inspired techniques, including microfluidic devices and bioreactors, exist to generate and culture organoids at high throughput. Similarly, data analysis and deep learning-based techniques, that were established in in vivo models, are now being used to extract quantitative information from synthetic systems. Finally, theory and data-driven in silico modeling are starting to provide a system-level understanding of organoids and make predictions to be tested with further experiments. Here, we discuss our vision of how engineering, data science and theoretical modeling will synergize to offer an unprecedented view of embryonic development. For every one of these three scientific domains, we discuss examples from in vivo and in vitro systems that we think will pave the way to future developments of synthetic embryology., Competing Interests: Declaration of competing interest The authors have no competing interests., (Copyright © 2020. Published by Elsevier Inc.)

Craniofacial development, one of the most complex sequences of developmental events in embryology, features a uniquely transient, pluripotent stem cell-like population known as the neural crest (NC). Neural crest cells (NCCs) originate from the dorsal aspect of the neural tube and migrate along pre-determined routes into the developing branchial arches and frontonasal plate. The exceptional rates of proliferation and migration of NCCs enable their diverse contribution to a wide variety of craniofacial structures. Subsequent differentiation of these cells gives rise to cartilage, bones, and a number of mesenchymally-derived tissues. Deficiencies in any stage of differentiation can result in facial clefts and abnormalities associated with craniofacial syndromes. A small number of conserved signaling pathways are involved in controlling NC differentiation and craniofacial development. They are used in a reiterated fashion to help define precise temporospatial cell and tissue formation. Although many aspects of their cellular and molecular control have yet to be described, it is clear that together they form intricately integrated signaling networks required for spatial orientation and developmental stability and plasticity, which are hallmarks of craniofacial development. Mutations that affect the functions of these signaling pathways are often directly or indirectly identified in congenital syndromes. Clinical applications of NC-derived mesenchymal stem/progenitor cells, persistent into adulthood, hold great promise for tissue repair and regeneration. Realization of NCC potential for regenerative therapies motivates understanding of the intricacies of cell communication and differentiation that underlie the complexities of NC-derived tissues.

Embryo evaluation and selection embody the aggregate manifestation of the entire in vitro fertilization (IVF) process. It aims to choose the "best" embryos from the larger cohort of fertilized oocytes, the majority of which will be determined to be not viable either as a result of abnormal development or due to chromosomal imbalances. Indeed, it is generally acknowledged that even after embryo selection based on morphology, time-lapse microscopic photography, or embryo biopsy with preimplantation genetic testing, implantation rates in the human are difficult to predict. Our pursuit of enhancing embryo evaluation and selection, as well as increasing live birth rates, will require the adoption of novel technologies. Recently, several artificial intelligence (AI)-based methods have emerged as objective, standardized, and efficient tools for evaluating human embryos. Moreover, AI-based methods can be implemented for other clinical aspects of IVF, such as assessing patient reproductive potential and individualizing gonadotropin stimulation protocols. As AI has the capability to analyze "big" data, the ultimate goal will be to apply AI tools to the analysis of all embryological, clinical, and genetic data in an effort to provide patient-tailored treatments. In this chapter, we present an overview of existing AI technologies in reproductive medicine and envision their potential future applications in the field., (Copyright © 2020 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

Collecting large numbers of rare cells for high-throughput molecular analysis remains a technical challenge, primarily due to limitations in existing technologies. In developmental biology this has impeded single-cell analysis of primordial organs, which derive from few cells. In this study, we share novel transgenic lines for rapid cell enrichment from zebrafish embryos using human surface antigens for immunological binding and magnetic sorting. As proof of principle, we tagged, enriched, and performed single-cell RNA sequencing on nascent hematopoietic stem/progenitor cells and endothelial cells from early embryos. Our method is a quick, efficient, and cost-effective approach to a previously intractable problem.

Objectives: To demonstrate a novel prototype microfluidic system for rapid isolation of sperm from real and simulated microdissection testicular sperm extraction samples., Methods: The novel microfluidic system was tested using minced testicular biopsies from patients with nonobstructive azoospermia. The samples were split into 2 portions, conventional processing vs microfluidic. The embryologists were blinded to the processing protocol and searched the specimens for sperm after processing. We recorded the number of sperm found and the time to sperm identification and compared the sperm retrieval rates., Results: When compared to conventional methods, samples processed through the microfluidic system were cleaner (decreased somatic cells/debris), with the average number of sperm identified per minute improving from 1.52 sperm per minute for the control and 13.5 sperm per minute with the device yielding an 8.88 fold improvement in the sperm found per minute for the device as compared to the control. Preliminary viability and morphology tests show a minimal impact on sperm processed through the microfluidic system., Conclusion: The presented microfluidic system can facilitate rapid and efficient isolation of sperm from microdissection testicular sperm extraction samples. A prospective clinical trial to verify these results is needed to confirm this preliminary data., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background and Objectives: The evaluative strength of available bibliometric tools in the field of clinical embryology has never been examined in the literature. The aim is to bring insight regarding the identity of clinical embryology research, introducing concerns when solely relying on the methodology of bibliometric analysis. Methods: An all-inclusive analysis of the most bibliometrically highlighted scientific contributions regarding the cornerstones of clinical embryology was performed employing the Scopus, Web of Science (WoS) and PubMed databases, between 1978-2018. An analysis of the number of publications, respective citations and h-index, g-index, along with m-quotient is presented. The top 30 contributing authors for each distinctive area of research are listed. An attempt at visualizing the yearly published articles, clusters, and collaborations of authors, along with the geographic origin of publications, is also presented. Results: Combining all searches and keywords yielded 54,522 results. In the Scopus database, employing the keyword "In Vitro Fertilization" yielded 41,292 results. The publications of the top five authors in each research field were analytically presented and compared to the total number of publications for each respective field. The research field of Preimplantation Genetic Diagnosis/Screening/Testing was allocated the highest percentage of publications produced by the top five authors. Regarding journal bibliometrics, based on the year 2017 metrics, there are only 29 journals according to WoS that refer to "Reproductive Biology", ranking it 187th among 235 disciplines. The USA produced the highest number of publications (12,537). Conclusion: Results indicate an explosion of interest published in the literature regarding the field of clinical embryology. Further analysis on collaborations and the trends involved should be of added value as productivity between countries varies significantly. This may guide researchers, in vitro fertilization professionals, and prospective authors during literature search, while proving useful regarding manuscript design and concurring on keywords and abstract content., Competing Interests: The authors declare no conflict of interest.

Plexus myentericus Auerbachi and Friedreich-Auerbach disease are widely used eponyms that are associated with eminent morphologist Leopold Auerbach (1828-1897), whose life is relatively little known due to limited access to his German-written XIX century biographies and lack of English biographical papers about him in world literature. Hereby we focused on hardly known achievements of Leopold Auerbach in the field of gametogenesis and embryology of invertebrates. Auerbach did not only confirm unicellularity of amoebas, which was previously discovered. He described cleavage of fertilized eggs of Ascaris nigrovenosa and Strongylus auricularis. Moreover, his accurate descriptions on germination of Paracentrotus lividus inspired a recognized German zoologist Oscar Hertwig (1849-1922). Auerbach also profoundly studied an encystation of Oxytricha pellionella on morphological grounds. His descriptions referred to karyokinesis as well as oogenesis and spermatogenesis to discover conjugations of spermatozoa in pairs in the epididymis of a beetle, Dytiscus marginalis. He also distinguished two types of spermatozoa of Paludina vivipara: the hairlike-shaped (German: haarförmigen) and the worm-shaped (wurmförmigen) ones of these fresh water (river) snails. His studies on germination (including cell division during cleavage of nematodes) inspired the others, e.g., Oscar Hertwig, and following generations to conclude that "Auerbach deserves the credit for having provided the first scientific foundation for modern teaching on fertilization" according to professor of anatomy Gustav Born (1851-1900) at Breslau University.

Objective: To evaluate the consistency and objectivity of deep neural networks in embryo scoring and making disposition decisions for biopsy and cryopreservation in comparison to grading by highly trained embryologists., Design: Prospective double-blind study using retrospective data., Setting: U.S.-based large academic fertility center., Patients: Not applicable., Intervention(s): Embryo images (748 recorded at 70 hours postinsemination [hpi]) and 742 at 113 hpi) were used to evaluate embryologists and neural networks in embryo grading. The performance of 10 embryologists and a neural network were also evaluated in disposition decision making using 56 embryos., Main Outcome Measures: Coefficients of variation (%CV) and measures of consistencies were compared., Results: Embryologists exhibited a high degree of variability (%CV averages: 82.84% for 70 hpi and 44.98% for 113 hpi) in grading embryo. When selecting blastocysts for biopsy or cryopreservation, embryologists had an average consistency of 52.14% and 57.68%, respectively. The neural network outperformed the embryologists in selecting blastocysts for biopsy and cryopreservation with a consistency of 83.92%. Cronbach's α analysis revealed an α coefficient of 0.60 for the embryologists and 1.00 for the network., Conclusions: The results of our study show a high degree of interembryologist and intraembryologist variability in scoring embryos, likely due to the subjective nature of traditional morphology grading. This may ultimately lead to less precise disposition decisions and discarding of viable embryos. The application of a deep neural network, as shown in our study, can introduce improved reliability and high consistency during the process of embryo selection and disposition, potentially improving outcomes in an embryology laboratory., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Public experimental embryology opens a relationship between an embryo and an amateur transgenic designer. Artists produce real-world effects by forcing hereditary aesthetics on developing bodies. This lab was meant to aid in public understanding of the relationship between transgenics and aesthetics. How do we to take an active and hands-on tactical stance on the role of hereditary designer and how does this help in public analysis of the bioethics of genetic engineering. Through naming and funeral rites, we assign the embryos an uncertain amount of clout or cultural worth. This lab is an example of how to understand the relationship between institutional oversight in pre-animal experimentation, embryonic dignity, and the problem of humane sacrifice. The intention is to make a hands-on wet bioart lab meant to aid in public comprehension of the range of politics and responsibilities involved in play at the level of heredity. The Developmental Biology and Transgenic Avian Embryology Bioart Wet Lab was held in Gorlaeus Laboratories, LIC, University of Leiden, Leiden, Netherlands, 2007.

Purpose of Review: The study of embryonic development through conventional microscopy has contributed significantly to the success of IVF. However, clinical pregnancy rates per transfer remain as low as 30% according to the latest records of European society if human reproduction and society if assisted reproduction. Considering the increased need to reduce the number of multiple pregnancies, the embryologist is required to improve embryo selection methods to reduce the number of embryos transferred and identify those with the highest implantation potential. This represents a big challenge considering that applying this strategy could jeopardize the overall success rates. New strategies have been proposed including the use of time-lapse systems among others. Although this technology has been used for a decade in IVF labs controversies still exist regarding its potential to substitute conventional morphology for embryo evaluation., Recent Findings: Lately, different algorithms have been developed correlating embryo kinetics to blastocyst formation, implantation potential, chromosomal content and live birth rate. Moreover, automation and the use of artificial intelligence have recently been introduced to improve this technology., Summary: The present review describes the time-lapse technology and the models available, using a Strength, Weaknesses, Opportunities and Threats analysis based on the clinical experience and published data since 2010.

Study Question: Can embryology key performance indicators (KPIs) detect shifts in laboratory performance that precede changes in clinical outcomes?, Summary Answer: Day 5 usable blastocyst rate (D5BUR) is an important embryology KPI that complements total usable blastocyst rate (TBUR) in its ability to rapidly identify adverse embryology outcomes, prior to changes in clinical outcomes., What Is Known Already: The hypothesis that monitoring performance of an IVF laboratory using statistical process controls (SPCs) can act as an early warning signal of shifts in laboratory conditions is a hypothesis that requires validation. The Vienna consensus report recently defined KPIs for monitoring fresh IVF and ICSI cycles, but the effectiveness of using these KPIs for detecting clinically relevant shifts following changes in laboratory processes is unknown., Study Design, Size, Duration: A retrospective, multicentre, analysis of KPIs for 1971 fresh IVF and ICSI cycles during three consecutive 5-month periods (P1, P2 and P3) during which the culture medium was changed in the middle period., Participants/materials, Setting, Methods: ICSI fertilisation rate, IVF fertilisation rate, D5BUR, TBUR and clinical pregnancy rate (CPR) were tracked monthly and analysed for SPC using Shewhart control charts. Out-of-control KPIs were identified by warning (2-sigma) and control (3-sigma) limits. The effect of the laboratory culture medium change on embryology KPIs and cumulative CPR was investigated using a one-way ANOVA or Pearson Chi-squared test and logistic regression., Main Results and the Role of Chance: D5BUR decreased from 32 to 25% after the culture medium was changed, and the decrease was detected within 1 week after the change (P < 0.0001). D5BUR subsequently increased after a change back to the original medium. A decrease in CPR (51-36%) after the medium change was also observed but was not detected until 3 months after the shift in D5BUR (P = 0.0005). Overall, the change in culture medium independently influenced D5BUR, CPR and cumulative CPR. Importantly, TBUR (41%) was not affected by the change in culture medium, remaining within control limits for all three culture periods, indicating that the overall blastocyst rate alone may not sufficiently monitor embryology laboratory performance., Limitations Reasons for Caution: The statistical KPI monitoring system demonstrated by the current study may be less effective at identifying KPI shifts in smaller clinics with lower cycle volumes. Live-birth rate per cycle started was not included as a clinical KPI., Wider Implications of the Findings: This study demonstrates that statistical KPI monitoring systems have the potential to provide systematic, early detection of adverse outcomes in ART laboratories after planned or unexpected shifts in conditions., Study Funding/competing Interest(s): No external funds were used for the study. The authors have no conflicts of interest., Trial Registration Number: Not applicable.

Reactions of embryonic tissues to a distributed and concentrated stretching are described and compared with the mechanics of the normal gastrulation movements. A role of mechanically stressed dynamic cell structures in the gastrulation, demarcation of notochord borders and in providing proportionality of the axial rudiments is demonstrated. A morphomechanical scheme of amphibian gastrulation is presented., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A list of papers and books of the late Lev V. Beloussov was compiled and is available in Word and EndNote Supplements. The breadth of his work is briefly described., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In order to understand living organisms, considerable experimental efforts and resources have been devoted to correlate genes and their expressions with cell, tissue, organ and whole organisms' phenotypes. This data driven approach to knowledge discovery has led to many breakthrough in our understanding of healthy and diseased states, and is paving the way to improve the diagnosis and treatment of diseases. Complementary to this data-driven approach, computational models of biological systems based on first principles have been developed in order to deepen our understanding of the multi-scale dynamics that drives normal and pathological biological functions. In this paper we describe the biological, physical and mathematical concepts that led to the design of a Computational Morphogenesis (CM) platform baptized Generic Modeling and Simulating Platform (GMSP). Its role is to generate realistic 3D multi-scale biological tissues from virtual stem cells and the intended target applications include in virtuo studies of normal and abnormal tissue (re)generation as well as the development of complex diseases such as carcinogenesis. At all space-scales of interest, biological agents interact with each other via biochemical, bioelectrical, and mechanical fields that operate in concert during embryogenesis, growth and adult life. The spatio-temporal dependencies of these fields can be modeled by physics-based constitutive equations that we propose to examine in relation to the landmark biological events that occur during embryogenesis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Morphological and genoarchitectonic studies have conclusively shown that the human brain (and that of all vertebrates) is segmented i. e. is fundamentally composed of a number of rostrocaudally arranged brain segments or neuromeres. However in the current neuroimaging literature the term segmentation, derived initially from computer graphics technology, is used instead to indicate the neuroanatomical parcellation or subdivision of neural structures in the fully formed brain, especially the cortex. The neuroimaging community should be aware of the prior use of this term in the parallel discipline of neuroembryology, and should use a different one e.g. parcellation to avoid any confusion between the two growing disciplines., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Evaluation of the skeleton in laboratory animals is a standard component of developmental toxicology testing. Standard methods of performing the evaluation have been established, and modification of the evaluation using imaging technologies is under development. The embryology of the rodent, rabbit, and primate skeleton has been characterized in detail and summarized herein. The rich literature on variations and malformations in skeletal development that can occur in the offspring of normal animals and animals exposed to test articles in toxicology studies is reviewed. These perturbations of skeletal development include ossification delays, alterations in number, shape, and size of ossification centers, and alterations in numbers of ribs and vertebrae. Because the skeleton is undergoing developmental changes at the time fetuses are evaluated in most study designs, transient delays in development can produce apparent findings of abnormal skeletal structure. The determination of whether a finding represents a permanent change in embryo development with adverse consequences for the organism is important in study interpretation. Knowledge of embryological processes and schedules can assist in interpretation of skeletal findings., (© 2018 The Authors. Birth Defects Research Published by Wiley Periodicals, Inc.)

Human embryology is a core subject for medicine and current research. While animal models of development now have significant online resources available, the vast majority of human embryonic material is locked up in historic collections. When accessed today, these collections are still contributing to our understanding of human development. This paper describes two online resources for studying human development that are unlocking these invaluable collections and providing related human developmental resources. The first of these is the online Embryology website (http://tiny.cc/Embryo) that links the human developmental timeline to historic and current research findings. Secondly is the Digital Embryology Consortium (https://human-embryology.org), an international research partnership to digitise, preserve, and make the major embryology histological collections available for researchers. By making this histological material more widely available to researchers with new methods of analysis, a better understanding of human development can be reached. This also opens the opportunity for new 3D reconstruction and virtual reality representation of these embryos., (© 2019 S. Karger AG, Basel.)

The Kyoto Collection of Human Embryos and Fetuses, the largest collection of human embryos worldwide, was initiated in the 1960s, and the Congenital Anomaly Research Center of Kyoto University was established in 1975 for long-term storage of the collection and for the promotion of research into human embryonic and fetal development. Currently, the Kyoto Collection comprises approximately 45,000 specimens of human embryonic or fetal development and is renowned for the following unique characteristics: (1) the collection is considered to represent the total population of fetal specimens nationwide in Japan, (2) it comprises a large number of specimens with a variety of external malformations, and (3) for most specimens there are clinical and epidemiological data from the mothers and the pregnancies concerned. Therefore, the specimens have been used extensively for morphological studies and could potentially be used for epidemiological analysis. Recently, several new approaches such as DNA extraction from formalin-fixed specimens or geometric morphometrics have been adopted and it is to be expected that further technological advances will facilitate new studies on the specimens of the Kyoto Collection as well as of other human embryo collections worldwide. Permanent preservation of the Kyoto Collection is, therefore, of paramount importance so that it will continue to contribute to human embryological studies in the future., (© 2018 S. Karger AG, Basel.)

While the external vertebrate body plan appears bilaterally symmetrical with respect to anterior-posterior and dorsal-ventral axes, the internal organs are arranged with a striking and invariant left-right asymmetry. This laterality is important for normal body function, as alterations manifest as numerous human birth defect syndromes. The left-right axis is set up very early during embryogenesis by an initial and still poorly understood break in bilateral symmetry, followed by a cascade of molecular events that was discovered 20 years ago in the chick embryo model. This gene regulatory network leads to activation of the pitx2 gene on the left side of the embryo which ultimately establishes asymmetric organogenesis of the heart, gut, brain, and other organs. In this review, we highlight the crucial contributions of the avian model to the discovery of the differential transcriptional cascades operating on the Left and Right sides, as well as to the physiological events operating upstream of asymmetric gene expression. The chick was not only instrumental in the discovery of mechanisms behind left-right patterning, but stands poised to facilitate inroads into the most fundamental aspects that link asymmetry to the rest of evolutionary developmental biology.

Some 25 years ago, a clone was identified that contained the chicken Slug sequences (now called Snail2 ). How could we anticipate at that time how much the chick embryo would help us to understand the ins and outs of cell migration during development and in disease? Indeed, the chick embryo helped us identify Snail2 as the first transcription factor that could induce the epithelial-mesenchymal transition (EMT), key for the migration of embryonic and cancer cells.

The aim of this review is to highlight some of the key contributions to our understanding of craniofacial research from work carried out with the chicken and other avian embryos. From the very first observations of neural crest cell migration to the fusion of the primary palate, the chicken has proven indispensable in facilitating craniofacial research. In this review we will look back to the premolecular studies where "cut and paste" grafting experiments mapped the fate of cranial neural crest cells, the role of different tissue layers in patterning the face, and more recently the contribution of neural crest cells to jaw size and identity. In the late 80's the focus shifted to the molecular underpinnings of facial development and, in addition to grafting experiments, various chemicals and growth factors were being applied to the face. The chicken is above all else an experimental model, inviting hands-on manipulations. We describe the elegant discoveries made by directly controlling signaling either in the brain, in the pharyngeal arches or in the face itself. We cover how sonic hedgehog (Shh) signals to the face and how various growth factors regulate facial prominence identity, growth and fusion. We also review abnormal craniofacial development and how several type of spontaneous chicken mutants shed new light on diseases affecting the primary cilium in humans. Finally, we bring out the very important role that the bird beak has played in understanding amniote evolution. The chicken, duck and quail have been and will continue to be used as experimental models to explore the evolution of jaw diversity and the morphological constraints of the vertebrate face.

The chick embryo has served as a workhorse for experimental embryological studies designed to elucidate mechanisms underlying neurulation, the process that forms the neural tube, the rudiment of the entire adult central nervous system. Early chick embryos developing in whole-embryo culture can be readily manipulated in cut-and-paste-type experiments, and this attribute makes this model system unparalleled for studying the morphogenesis of embryos and their organ rudiments. How the chick embryo and experimental embryology have contributed to our understanding of critical events of neurulation are summarized.

The pioneering study of Eyal-Giladi and Kochav (EG&K; Eyal-Giladi and Kochav, 1976) on the early developmental stages-from fertilization, through oviposition, to the gastrulation process-set the standard for characterizing chicken embryos, and has been used in numerous studies over the years. During uterine development, the chicken embryo undergoes dramatic changes, extremely rapid cell cycles, massive cell death, and axial determination processes. However, once the egg is laid, the temperature drops and the embryo enters into a diapause-like state. This phenomenon is utilized to store fertile eggs prior to incubation. The ability to resume development to hatching, following storage, relies on several factors, including the number of living cells and the embryonic developmental stage. These factors are highly influenced by the storage conditions-mainly duration and temperature. Thus, to study the effects of storage conditions on embryonic viability, a comprehensive characterization of the starting point-shortly after oviposition-is needed. In this study, we characterized freshly laid broiler eggs from Ross 308 flocks for embryonic developmental stage, total cell count, and cell viability. Using the novel high-resolution episcopic microscopy (HREM) system, we show, for the first time, high-resolution 3D morphological models of blastoderms which allow for highly accurate embryonic staging. Staging was also done under a dissecting microscope thus allowing for a direct side-by-side comparison of the two methods. Analysis of freshly laid blastomeres showed that the total nucleus count increases with developmental stage from ∼60,000 at stage X EG&K to ∼130,000 at stage XIII EG&K, whereas the proportion of mitotic index and dying cells at oviposition are ∼2% and ∼5%, respectively. Moreover, staging embryos from young and old flocks revealed that the blastoderms of the old flocks are more developed. Specifically, the predominant embryonic stages were XI and XII EG&K in young and old flocks, respectively. Collectively, we characterized parameters that can serve to analyze the maladaptive effects of prolonged storage under various conditions on embryo survival., (© 2017 Poultry Science Association Inc.)

John Saunders was a highly skilled embryologist who pioneered the study of limb development. His studies on chick embryos provided the fundamental framework for understanding how vertebrate limbs develop. This framework inspired generations of scientists and formed the bridge from experimental embryology to molecular mechanisms. Saunders investigated how feathers become organized into tracts in the skin of the chick wing and also identified regions of programmed cell death. He discovered that a region of thickened ectoderm that rims the chick wing bud - the apical ectodermal ridge - is required for outgrowth and the laying down of structures along the proximo-distal axis (long axis) of the wing, identified the zone of polarizing activity (ZPA; polarizing region) that controls development across the anteroposterior axis ("thumb to little finger "axis) and contributed to uncovering the importance of the ectoderm in development of structures along the dorso-ventral axis ( "back of hand to palm" axis). This review looks in depth at some of his original papers and traces how he made the crucial findings about how limbs develop, considering these findings both in the context of contemporary knowledge at the time and also in terms of their immediate impact on the field., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: To identify different blastocyst classification systems used by embryologists in Latin American countries and evaluate the possibility of establishing a consensus among these countries., Methods: An E-mail survey was carried out through the Latin American Network of Assisted Reproduction (REDLARA) aimed at embryologists from assisted reproduction centers in Latin countries., Results: Sixty surveys were collected from 12 Latin American countries, of which 66.7% had >10years of professional practice as embryologists. Seven different blastocyst classification systems were reported, of which 5 have previously been described in the literature., Conclusion: Although the group of embryologists surveyed use different blastocyst classification systems, most in this group consider that the embryo score system should be unified in their countries as well as in the region.

This protocol is used to create a convenient chamber for mouse embryos for microscopic observation and imaging., (© 2017 Cold Spring Harbor Laboratory Press.)

Advances in embryology, genetics, and regenerative medicine regularly attract attention from scientists, scholars, journalists, and policymakers, yet implications of these advances may be broader than commonly supposed. Laboratories culturing human embryos, editing human genes, and creating human-animal chimeras have been working along lines that are now becoming intertwined. Embryogenic methods are weaving traditional in vivo and in vitro distinctions into a new “in vivitro” (in life in glass) fabric. These and other methods known to be in use or thought to be in development promise soon to bring society to startling choices and discomfiting predicaments, all in a global effort to supply reliably rejuvenating stem cells, to grow immunologically non-provocative replacement organs, and to prevent, treat, cure, or even someday eradicate diseases having genetic or epigenetic mechanisms. With humanity's human-engineering era now begun, procedural prohibitions, funding restrictions, institutional controls, and transparency rules are proving ineffective, and business incentives are migrating into the most basic life-sciences inquiries, wherein lie huge biomedical potentials and bioethical risks. Rights, health, and heritage are coming into play with bioethical presumptions and formal protections urgently needing reassessment.

The Turing reaction-diffusion model explains how identical cells can self-organize to form spatial patterns. It has been suggested that extracellular signaling molecules with different diffusion coefficients underlie this model, but the contribution of cell-autonomous signaling components is largely unknown. We developed an automated mathematical analysis to derive a catalog of realistic Turing networks. This analysis reveals that in the presence of cell-autonomous factors, networks can form a pattern with equally diffusing signals and even for any combination of diffusion coefficients. We provide a software (available at http://www.RDNets.com) to explore these networks and to constrain topologies with qualitative and quantitative experimental data. We use the software to examine the self-organizing networks that control embryonic axis specification and digit patterning. Finally, we demonstrate how existing synthetic circuits can be extended with additional feedbacks to form Turing reaction-diffusion systems. Our study offers a new theoretical framework to understand multicellular pattern formation and enables the wide-spread use of mathematical biology to engineer synthetic patterning systems.

Reptile development is an intriguing research target for understating the unique morphogenesis of reptiles as well as the evolution of vertebrates. However, there are numerous difficulties associated with studying development in reptiles. The number of available reptile eggs is usually quite limited. In addition, the reptile embryo is tightly adhered to the eggshell, making it a challenge to isolate reptile embryos intact. Furthermore, there have been few reports describing efficient procedures for isolating intact embryos especially prior to pharyngula stage. Thus, the aim of this review is to present efficient procedures for obtaining early-stage reptilian embryos intact. We first describe the method for isolating early-stage embryos of the Japanese striped snake. This is the first detailed method for obtaining embryos prior to oviposition in oviparous snake species. Second, we describe an efficient strategy for isolating early-stage embryos of the soft-shelled turtle., (© 2016 Japanese Society of Developmental Biologists.)

The quantitative and systematic analysis of embryonic cell dynamics from in vivo 3D+time image data sets is a major challenge at the forefront of developmental biology. Despite recent breakthroughs in the microscopy imaging of living systems, producing an accurate cell lineage tree for any developing organism remains a difficult task. We present here the BioEmergences workflow integrating all reconstruction steps from image acquisition and processing to the interactive visualization of reconstructed data. Original mathematical methods and algorithms underlie image filtering, nucleus centre detection, nucleus and membrane segmentation, and cell tracking. They are demonstrated on zebrafish, ascidian and sea urchin embryos with stained nuclei and membranes. Subsequent validation and annotations are carried out using Mov-IT, a custom-made graphical interface. Compared with eight other software tools, our workflow achieved the best lineage score. Delivered in standalone or web service mode, BioEmergences and Mov-IT offer a unique set of tools for in silico experimental embryology.

The chronically instrumented pregnant sheep has been used as a model of human fetal development and responses to pathophysiologic stimuli such as endotoxins, bacteria, umbilical cord occlusions, hypoxia and various pharmacological treatments. The life-saving clinical practices of glucocorticoid treatment in fetuses at risk of premature birth and the therapeutic hypothermia have been developed in this model. This is due to the unique amenability of the non-anesthetized fetal sheep to the surgical placement and maintenance of catheters and electrodes, allowing repetitive blood sampling, substance injection, recording of bioelectrical activity, application of electric stimulation and in vivo organ imaging. Here we describe the surgical instrumentation procedure required to achieve a stable chronically instrumented non-anesthetized fetal sheep model including characterization of the post-operative recovery from blood gas, metabolic and inflammation standpoints.

The developmental origin of health and disease hypothesis posits that early-life exposures, including prenatal, can influence disease outcomes throughout the entire lifespan of an organism. Over the past 30 years, scientific researchers have compiled robust epidemiological and mechanistic data showing the effects of early-life nutrition, chemical exposures, and stress on prenatal programing and toxicity. Using novel techniques in genomics and epigenetics, science is now establishing strong links between low-level early-life environmental exposures and the later development of noncommunicable diseases, such as cardiovascular disease, obesity, diabetes, neurodevelopmental and neurodegenerative disease, reproductive effects, immune system function and cancer. Now scientists must engage with communities, industry, policy makers, and clinicians to leverage our newfound understanding of prenatal programing and toxicity into better health outcomes across the lifespan.