Early Embryology Research Articles

Myelomeningocele Closure: An Embryological Perspective.

Myelomeningoceles (MMCs) represent a localized failure of primary neurulation during the fourth week of embryonic development. There are a number of misconceptions concerning the proper identification, classification, and surgical repair of these lesions. To provide surgeons with a working knowledge of early neural embryology as it relates to MMC closure as a localized failure of primary neurulation. We review the embryology of early neural development as a means of providing neurosurgeons with a better understanding of MMC closure techniques. Early neural development predicts the anatomy of MMC and knowledge of embryology helps guide repair. Repair of MMC is enhanced by knowing early neural development.

<p><strong>Early embryology of Vochysiaceae and some insights into its phylogeny and intrafamilial taxonomy</strong></p>

Embryological data provides insights into the taxonomy and evolution of angiosperms. Vochysiaceae is a mostly Neotropical family whose phylogenetic position was greatly influenced by reconstructions based on molecular data, and despite its monosymmetric and oligostemonous flowers, was included as a sister group of polysymmetric and polystemonous Myrtaceae. However, molecular data has yet to resolve the relationships between the genera inside the family. We analysed the early embryology of some species of five out of the six generally accepted Neotropical genera using sequential histological analyses to compare the microsporogenesis and gametogenesis and megasporogenesis and gametogenesis between clades and with the embryology of the well-studied Myrtales. We observed some marked differences in timing and developmental stages, which somewhat corroborate the clades defined from molecular data. Multiple archesporium and embryo sacs, as well as megagametophyte maturation and fertilization long after anthesis, characterized the Qualea-Ruizteranea-Callisthene (QRC) clade, while single embryo sac mature at anthesis characterized the Vochysia-Salvertia (VS) clade. Tri-cellular pollen only occurred in Salvertia convallariodora. Seven of the eight main embryological features supported the Myrtales as present in Vochysiaceae and the remaining one, inner integument with two layers of cells, was observed in some Qualea. Thus, the studied Vochysiaceae embryology conforms very well within the order and only their strongly monosymmetric and oligostemonous flowers are less common among Myrtales.

An early chick embryo as learning model for study of embryology

Abstract Background: In medical education, learning happens by variety of perceptions. In basic science Anatomy, visualization of real structures gives rich learning experience. This type seems deficient in human embryology, that too in the early phases. Aim: With the basic concept of'ontogeny repeats phylogeny', for the enrichment of learning early embryology, chick embryos have been used. Materials and methods: 30 commercially available chicken eggs and 30 Gallus domesticus [country chicken] eggs collected from nearby villages were hatched for embryos to whole mount, fix and stain. Results: Successful hatching rates were more in favour of Gallus domesticus eggs [76%] compared to others [26%] Conclusion: This experiment guides the easiest and simplest possible ways to successfully establish the learning module for early embryology in departmental setup using Gallus domesticus eggs. Observation of brain swellings, heart swelling optic vesicle, nasal pit, pharyngeal clefts, neural tube, somites and limb buds, vitelline vessels provide valuable learning experience by direct interaction with the real environment. This bridges the gap of seeing what is not usually observed and strengthens educational embryology

An early chick embryo as learning model for study of embryology

Background: In medical education, learning happens by variety of perceptions. In basic science Anatomy, visualization of real structures gives rich learning experience. This type seems deficient in human embryology, that too in the early phases. Aim: With the basic concept of’ontogeny repeats phylogeny’, for the enrichment of learning early embryology, chick embryos have been used. Materials and methods: 30 commercially available chicken eggs and 30 Gallus domesticus [country chicken] eggs collected from nearby villages were hatched for embryos to whole mount, fix and stain. Results: Successful hatching rates were more in favour of Gallus domesticus eggs [76%] compared to others [26%] Conclusion: This experiment guides the easiest and simplest possible ways to successfully establish the learning module for early embryology in departmental setup using Gallus domesticus eggs. Observation of brain swellings, heart swelling optic vesicle, nasal pit, pharyngeal clefts, neural tube, somites and limb buds, vitelline vessels provide valuable learning experience by direct interaction with the real environment. This bridges the gap of seeing what is not usually observed and strengthens educational embryology

From stem cells to human development: a distinctly human perspective on early embryology, cellular differentiation and translational research.

Over 100 scientists with common interests in human development, disease and regeneration gathered in late September 2016 for The Company of Biologists' second 'From Stem Cells to Human Development' meeting held in historic Southbridge. In this Meeting Review, we highlight some of the exciting new findings that were presented, and discuss emerging themes and convergences in human development and disease that arose during these discussions.

Sporophytic apomixis in polyembryonic Handroanthus serratifolius (Vahl) S.O. Grose (Bignoniaceae) characterizes the species as an agamic polyploid complex

Neopolyploidy has been associated with gametophytic apomixis and breakdown of gametophytic self-incompatibility. Nevertheless, Bignoniaceae presents agamic polyploid complexes with neopolyploidy associated to sporophytic apomixis. Apomictic populations are commonly polyploid, polyembryonic and self-fertile, while diploids are mostly late-acting self-incompatible (LSI) and monoembryonic. Contrastingly, Handroanthus serratifolius shows hexaploid monoembryonic and polyembryonic populations, although breeding system has been studied only for monoembryonic individuals, which are LSI. Our aim here was to investigate breeding system and early embryology in polyembryonic individuals of H. serratifolius to define if they form an agamic polyploid complex. Experimental pollinations and histological analyzes of ovules and young seeds were carried out. Megasporogenesis and megagametogenesis occurred as in other sexual species of Bignoniaceae. The polyembryonic individuals were self-fertile and double fertilization was observed both after self and cross-pollinated pistils. Adventitious embryos originated from the hypostasis and integument of the ovule, indicating sporophytic apomixis. Adventitious embryo precursor cells occurred in all pistils, including unpollinated ones. But unpollinated pistils aborted possibly due to absence of endosperm, and pollination was required for fruit-set (pseudogamy). It is possible that the self-fertility in polyembryonic individuals ensues as the initial endosperm of self-fertilized ovules supply early adventitious embryos development, and these embryos would later prevent the abortion of selfed pistils. The sporophytic apomixis in polyembryonic populations and the occurrence of sexual monoembryonic populations of H. serratifolius allows us to consider the species part of an agamic polyploid complex. But in contrast with other Handroanthus agamic complexes, both apomictic and sexual LSI plants were hexaploid.

Concepts of Cell Lineage in Mammalian Embryos.

Cell lineage is the framework for understanding cellular diversity, stability of differentiation, and its relationship to pluripotency. The special condition of in utero development in mammals has presented challenges to developmental biologists in tracing cell lineages but modern imaging and cell marking techniques have allowed the gradual elucidation of lineage relationships. Early experimental embryology approaches had limited resolution and relied of suboptimal cell markers and considerable disturbance to the embryos. Transgenic technology introduced genetic markers, particularly fluorescent proteins that, combined with sophisticated imaging modalities, greatly increase resolution and allow clonal analysis within lineages. The concept of cell lineage has also undergone evolution as it became possible to trace the lineage of cells based not only on their physical location or attributes but also on their gene expression pattern, thus opening up mechanistic lines of investigation into the determinants of cell lineage.

Modelos didáticos para compreensão do desenvolvimento embrionário inicial de animais domésticos

Neste trabalho é apresentada uma estratégia didática destinada a possibilitar uma melhor compreensão dos eventos embrionários iniciais do desenvolvimento de animais domésticos, para alunos de graduação em Medicina Veterinária da Universidade Federal do Mato Grosso do Sul, Brasil. Para tanto, foram confeccionados modelos em biscuit que apresentam aspectos morfológicos do desenvolvimento inicial, como a célula fertilizada, clivagem inicial, formação de blastocisto e dos folhetos embrionários, desenvolvimento da cavidade amniótica, do celoma extraembrionário e do cório. O kit de modelos apresenta como inovação características morfológicas diferentes dos modelos amplamente comercializados e utilizados para ensinar embriologia humana, uma vez que inclui peculiaridades observadas apenas em animais domésticos, como o elongamento do blastocisto e a formação de pregas amnióticas para o desenvolvimento da cavidade amniótica. O kit desenvolvido e aplicado em aula prática foi aceito pelos alunos de graduação de Medicina Veterinária como elemento favorável ao aprendizado de embriologia.

Effects of salinity and sea salt type on egg activation, fertilization, buoyancy and early embryology of European eel, Anguilla anguilla.

Improper activation and swelling of in vitro produced eggs of European eel, Anguilla anguilla, has been shown to negatively affect embryonic development and hatching. We investigated this phenomenon by examining the effects of salinity and sea salt type on egg dimensions, cell cleavage patterns and egg buoyancy. Egg diameter after activation, using natural seawater adjusted to different salinities, varied among female eels, but no consistent pattern emerged. Activation salinities between 30-40 practical salinity unit (psu) produced higher quality eggs and generally larger egg diameters. Chorion diameters reached maximal values of 1642 ± 8 μm at 35 psu. A positive relationship was found between egg neutral buoyancy and activation salinity. Nine salt types were investigated as activation and incubation media. Five of these types induced a substantial perivitelline space (PVS), leading to large egg sizes, while the remaining four salt types resulted in smaller eggs. All salt types except NaCl treatments led to high fertilization rates and had no effect on fertilization success as well as egg neutral buoyancies at 7 h post-fertilization. The study points to the importance of considering ionic composition of the media when rearing fish eggs and further studies are encouraged.

Folding into being: early embryology and the epistemology of rhythm.

Historians have often described embryology and concepts of development in the period around 1800 in terms of "temporalization" or "dynamization". This paper, in contrast, argues that a central epistemological category in the period was "rhythm", which played a major role in the establishment of the emerging discipline of biology. I show that Caspar Friedrich Wolff's epigenetic theory of development was based on a rhythmical notion, namely the hypothesis that organic development occurs as a series of ordered rhythmical repetitions and variations. Presenting Christian Heinrich Pander's and Karl Ernst von Baer's theory of germ layers, I argue that Pander and Baer regarded folding as an organizing principle of ontogenesis, and that the principle's explanatory power stems from their understanding of folding as a rhythmical figuration. In a brief discussion of the notion of rhythm in contemporary music theory, I identify an underlying physiological epistemology in the new musical concept of rhythm around 1800. The paper closes with a more general discussion of the relationship between the rhythmic episteme, conceptions of life, and aesthetic theory at the end of the eighteenth century.

A REVIEW OF THE DOCTOR THESIS ON THE OXYURIDS OF INSECTS BY OSMAN GALEB, THE PIONEER EGYPTIAN ZOOLOGIST FROM THE 19TH CENTURY

The present communication reviews the recently discovered Doctor Thesis of Osman Galeb (from the Egyptian School of Medicine), who was the first Egyptian zoologist in modern times and the only one in the 19th century. Starting his work on the oxyurids of insects in the University of Montpellier, Galeb was granted his degree in 1878 from the Sorbonne, Paris. Out of 40 species of oxyurids of insects Galeb was able to identify, 11 species were ultimately studied and illustrated. Seven of these were of the terrestrial Blattidae, and four of the aquatic Hydrophilidae. The different body systems of the oxyurids were comparatively described, with the reproductive organs, in particular, in some detail. Aspects of copulation, fertilization, early embryology and development were also covered. Critical notes on Galeb’s results and discussion are given.

Spiral cleavage and early embryology of a loxosomatid entoproct and the usefulness of spiralian apical cross patterns for phylogenetic inferences

BackgroundAmong the four major bilaterian clades, Deuterostomia, Acoelomorpha, Ecdysozoa, and Lophotrochozoa, the latter shows an astonishing diversity of bodyplans. While the largest lophotrochozoan assemblage, the Spiralia, which at least comprises Annelida, Mollusca, Entoprocta, Platyhelminthes, and Nemertea, show a spiral cleavage pattern, Ectoprocta, Brachiopoda and Phoronida (the Lophophorata) cleave radially. Despite a vast amount of recent molecular phylogenetic analyses, the interrelationships of lophotrochozoan phyla remain largely unresolved. Thereby, Entoprocta play a key role, because they have frequently been assigned to the Ectoprocta, despite their differently cleaving embryos. However, developmental data on entoprocts employing modern methods are virtually non-existent and the data available rely exclusively on sketch drawings, thus calling for thorough re-investigation.ResultsBy applying fluorescence staining in combination with confocal microscopy and 3D-imaging techniques, we analyzed early embryonic development of a basal loxosomatid entoproct. We found that cleavage is asynchronous, equal, and spiral. An apical rosette, typical for most spiralian embryos, is formed. We also identified two cross-like cellular arrangements that bear similarities to both, a "molluscan-like" as well as an "annelid-like" cross, respectively.ConclusionsA broad comparison of cleavage types and apical cross patterns across Lophotrochozoa shows high plasticity of these character sets and we therefore argue that these developmental traits should be treated and interpreted carefully when used for phylogenetic inferences.

Development of Apolipoprotein E–Deficient Mice

The first mouse carrying a deletion mutation in its apolipoprotein E (apoE) gene was born in our mouse colony in the summer of 1991. Our ongoing experiments to that point had indicated that this would happen, but the realization that the mouse in front of my eyes had inherited a mutation that we had designed and made in the laboratory filled me with awe. It did not occur to me immediately that this mouse would develop hypercholesterolemia and atherosclerosis and dictate the direction of my research for the next 20 years. I here briefly describe the background and my personal experience that led to the development of apoE-deficient mice as a model for human atherosclerosis. As a research scientist in the Department of Genetics at the University of Wisconsin, my main interest during the early 1980s was directed toward understanding how different types of DNA recombination contribute to the architecture and diversity of individual genomes within human populations and to DNA differences between humans and nonhuman primates. My studies clearly showed that new alleles and new genes are constantly being formed in the human genome by recombinational events, particularly between existing members of multigene families. There also appeared to be hot spots for recombination. By tracing a history of the human haptoglobin-gene cluster from the present-day structures in human populations and in other primates, I found that a single recombination event between related genes often produces much more drastic changes in the genome than those that result from simple point mutations.1 Whether this frequent yet natural occurrence of homologous recombination in the mammalian genome could be used to alter the genome of mammalian cells in culture in a preplanned fashion became a question of interest to several laboratories.2,3 An affirmative answer was first obtained in 1985, …

Zebrafish as a model for vertebrate hematopoiesis

The zebrafish (Danio rerio) is a model organism making useful contributions in many areas of biological research. Zebrafish have proven particularly suitable for studying early development. The transparency and ex vivo development of zebrafish embryos means that early embryology can be easily visualized, especially using transgenic strains expressing fluorophores marking tissues of interest. High fecundity and tolerance of dense mutagenesis have made it a practical model for forward genetic screening and creation of mutagenized libraries from which stable mutant alleles can be recovered. Transient genetic manipulation by microinjection of mRNA (overexpression) or antisense morpholino oligonucleotides (knockdown) provide convenient methods for functionally assessing genetic regulatory pathways without the need for extended breeding strategies. A standout example of the utility of this model has been its application to modeling of the earliest stages of hematopoiesis. Zebrafish developmental hematopoiesis shows close correspondence to the development of the mammalian hematopoietic system and is regulated by conserved molecular pathways. This review highlights key recent studies that have used this model to provide insights into vertebrate hematopoietic development and innate immunity.

First cleavages, preblastula and blastula in the parthenogenetic mite Archegozetes longisetosus (Acari, Oribatida) indicate holoblastic rather than superficial cleavage

The mode of cleavage in the Acari is generalized as superficial or intralecithal, with a preceding phase of total (holoblastic) cleavage, but the knowledge is fragmentary and conclusions have been inconsistent, even when relating to the same species. Since no data about early embryology is available for the speciose group Oribatida, we studied Archegozetes longisetosus using transmission electron microscopy. We focused on early cleavages and the formation of the blastula, as these are the important and controversial points in early embryology of the Acari. We expected, as postulated for other acarine eggs, the early cleavages to be holoblastic and followed by a superficial preblastoderm stage. The early cleavages of A. longisetosus are holoblastic and blastomeres give rise to yolk-free micromeres and macromeres containing all the yolk. In contrast to expectations, the micromeres do not form a superficial preblastoderm layer. They are scattered along the embryonic surface and form an external, monocellular layer that covers the whole surface of the embryo. Since each of the existing TEM studies of mites shows this same pattern, and since this specialized form of total cleavage seems to be unique in Chelicerata, it may be the general mode of cleavage in Acari. However, the question will require much more investigation, especially since most data relate to the Actinotrichida and very few are currently available for species in the other major group, the Anactinotrichida.

Oocyte maturation failure: a syndrome of bad eggs

To show that disruption of meiotic competence results in cell cycle arrest, and the production of immature oocytes that are not capable of fertilization. Through an extensive review of animal studies and clinical case reports, we define the syndrome of oocyte maturation failure as a distinct oocyte disorder, present a classification system based on clinical parameters, and discuss the potential molecular origins for the disease.

The Rabbit(Oryctolagus cuniculus):A Model for Mammalian Reproduction and Early Embryology

INTRODUCTIONThe rabbit is a valuable animal model for a variety of biomedical research areas including in vitro fertilization, early embryology and organogenesis, neurophysiology, ophthalmology, and cardiovascular research. The rabbit is also used as a model for toxicology studies and analyses of drug effects on embryo and fetal development, as well as for research involving the immune system (e.g., host/pathogen interactions, asthma, arthritis, systemic lupus erythematosus). The rabbit’s most prominent use as a laboratory animal is antibody production; most biomedical research institutions thus provide the infrastructure and veterinary expertise for keeping rabbits. This article discusses current advances in applying modern life science research methods to basic and applied embryological research using the rabbit as a model for early intrauterine development in mammals, including state-of-the-art genomic tools and the sequencing data available (and planned) for the rabbit.

Unusual Development of the Mitraria Larva in the Polychaete Owenia collaris

Despite the wide variety of larval forms among polychaetes, most are clearly derived from the canonical spiralian trochophore. Within the genus Owenia (family Oweniidae), however, the mitraria larva lacks the characteristic ciliary bands of the trochophore, and those it has are monociliated, typically a deuterostome characteristic. Adult Owenia spp. also possess a monociliated epidermis and deuterostome-like nephridia. This study is the first detailed account of early embryology for any member of the Oweniidae. Light, confocal, and scanning electron microscopy were used to investigate organogenesis from fertilization through metamorphosis in Owenia collaris. Equal spiral cleavage yields an embryo with an unusually large blastocoel for a spiralian. The embryo undergoes gastrulation by invagination, and begins swimming 24 h after fertilization. Three important events deviate markedly from stereotypical polychaete embryogenesis. First, at the 8-cell stage the micromeres are larger than the macromeres, as in nemerteans. Second, the blastopore becomes the anus, as in some deuterostomes, while the stomodeum may form secondarily. Third, the cells that would form the prototroch in a canonical spiralian trochophore (1q(2) descendants) never undergo cleavage arrest, and the primary ciliated band of the mitraria never contains large, multiciliated cells. The mitraria larva thus represents a mixture of protostome and deuterostome developmental traits, suggesting that spiralian development is not so rigidly constrained as it might appear.

Embryology of Ceratopteris richardii (Pteridaceae, tribe Ceratopterideae), with emphasis on placental development

This comprehensive study of early embryology in Ceratopteris richardii combines light microscopy with the first ultrastructural evaluation of any pteridophyte embryo. Emphasis is placed on ontogeny of the foot and placental transfer cells. The embryology of C. richardii shares many similarities with that of other polypodiacious ferns while exhibiting distinctive division patterns. Formative embryonic stages have been reconstructed into three-dimensional models for ease of interpretation. The zygote divides perpendicular to the gametophyte plane and anterioposterior axis. This division establishes a prone embryological habit that maximizes rapid independent establishment of a leaf-root axis in a cordate gametophyte. After the formation of a globular eight-celled stage, initials of the first leaf, and root and shoot apical meristems are defined early by discrete formative divisions. Concomitantly, the foot expands and differentiates to transport nutrients from the gametophyte for the developing embryonic organs. Transfer cell wall ingrowth deposition begins in the gametophyte placental cells before the adjacent sporophyte cells just after the eight-celled stage. These observations provide an anatomical framework for future comparative developmental genetic studies of embryogenesis in free-sporing plants.

Congenital Microgastria and Primary Ciliary Dyskinesia in a Newborn with DiGeorge Syndrome and 22q11.2 Deletion

Congenital microgastria is an uncommon result of impairment of normal foregut development and rotation during early embryology. Only about 50 cases have been reported in the literature, mostly associated with other multiple congenital anomalies. The case of a female newborn with multiple abnormalities, including cardiovascular malformation (type I truncus arteriosus communis) with deletion of chromosome 22q11.2, severe immunodeficiency (DiGeorge syndrome), microgastria, and impaired mucociliary function (primary ciliary dyskinesia) is reported. An association between the deletion of chromosome 22q11.2, microgastria, and impaired mucociliary function has never been observed before. A casual association seems highly unlikely and we can not exclude the possibility of genetic mechanisms that may link those syndromes.