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At least 19 recordsLinked to original sources
PubMed1978

[Changes in gastrulation processes during phylogenesis in the animal world].

While treating gastrulation only as the entoderm individualization and formation of a double layer germ we do not take into consideration the alterations which gastrulation process has undergone in phylogenesis of different animal types. On the other hand, if entoderm formation (in vertebrates--with discoblastula) is not included in the notion of gastrulation, it will result in a complete incompartibility of gastrulation processes in other groups of animal kingdom. In birds and mammals, gastrulation is a double phasic process: the first phase--entoderm individualization by means of delamination (in combination with immigration), double layer germ formation; the second phase--individualization of mesoderm and chorda from the epiblast composition, a triple layer germ formation, the axial complex germs formation. During phylogenesis of the animal kingdom not only means and mechanisms of gastrulation change but also the contents of the process. For example, in Chordata besides increase in number of germ layers, gastrulation also includes the formation of the axial germ complex. As a result of gastrulational rearrangements of the blastula cellular maternal, the gastrula cell complex (germ layers and germs) come into a new system of interrelationships owing to which architectonic organizational bases of each particular animal type is laid down.

Animals↗
PubMed2025

Self-organization of mouse embryonic stem cells into reproducible pre-gastrulation embryo models via CRISPRa programming.

Embryonic stem cells (ESCs) can self-organize into structures with spatial and molecular similarities to natural embryos. During development, embryonic and extraembryonic cells differentiate through activation of endogenous regulatory elements while co-developing via cell-cell interactions. However, engineering regulatory elements to self-organize ESCs into embryo models remains underexplored. Here, we demonstrate that CRISPR activation (CRISPRa) of two regulatory elements near Gata6 and Cdx2 generates embryonic patterns resembling pre-gastrulation mouse embryos. Live single-cell imaging revealed that self-patterning occurs through orchestrated collective movement driven by cell-intrinsic fate induction. In 3D, CRISPRa-programmed embryo models (CPEMs) exhibit morphological and transcriptomic similarity to pre-gastrulation mouse embryos. CPEMs allow versatile perturbations, including dual Cdx2-Elf5 activation to enhance trophoblast differentiation and lineage-specific activation of laminin and matrix metalloproteinases, uncovering their roles in basement membrane remodeling and embryo model morphology. Our findings demonstrate that minimal intrinsic epigenome editing can self-organize ESCs into programmable pre-gastrulation embryo models with robust lineage-specific perturbation capabilities.

Animals↗
PubMed1977

[Structure of the morphogenetic movements of gastrulation in Anura. II. The elementary morphogenetic processes].

The clinostate rotation causes a wide range of gastrulation abnormalities in the Anura. A special investigation has shown that all gastrulation variants may be represented as various spatial-temporal compositions of the same morphogenetic processes isolated by means of formal experimental procedure. These processes are structurally stable rearrangements of tissue morphology and are spread in the tissue as a wave embracing more and more cells. The change of one local morphology for another may proceed either in the form of "shock wave", a moving distinct border between the cells already switched and not yet switched to the new automorphous movement, or in the form of "deployment" when the transition from one local morphology to another is continuously deployed in space.

Amphibians↗
PubMed1979

Biosynthesis of N-glycosidically linked glycoproteins during gastrulation of sea urchin embryos.

Embryos of the sea urchin, Stronglyocentrotus purpuratus, synthesize several classes of sulfated and non-sulfated glycoproteins during gastrulation. The antibiotic tunicamycin, which is a specific inhibitor of the N-glycosylation of proteins, inhibits the synthesis of lipid-linked oligosaccharides in these embryos at concentrations which have little effect on the biosynthesis of other classes of glycolipids or on protein synthesis. As a consequence of this inhibition, glycoproteins with oligosaccharide side chains of the general type (Man)5-7-(GlcNAc)2 are not synthesized. In addition, the biosynthesis of a novel class of sulfated glycoproteins is inhibited. In contrast, no effect upon the synthesis of sulfated glycosaminoglycans is seen. The morphogenetic consequence of tunicamycin treatment is that development of embryos from the mesenchyme blastula to the gastrula stage is arrested. The results provide evidence that during development glycoproteins containing both unsulfated and sulfated N-glycosidically linked oligosaccharide chains are synthesized via the lipid-linked pathway. The biosynthesis of these molecules appears to be a prerequisite to the differentiation and morphogenesis that occurs during gastrulation.

Animals↗
PubMed2025

Modeling early gastrulation in human blastoids with DNA methylation patterns of natural blastocysts.

Blastoids are a promising model for studying early human embryogenesis, but current models have limitations in post-implantation development and lack comprehensive epigenetic assessments, especially regarding genomic imprinting. These issues can lead to failures in accurately modeling early embryonic development. In this study, we developed a high-fidelity blastoid model using 4 chemicals + leukemia inhibitory factor (LIF) (4CL) naive human pluripotent stem cells (hPSCs) (4CL blastoids). 4CL blastoids closely resemble human blastocysts in morphology and transcriptional profiles, exhibiting similar DNA methylation and gene imprinting patterns. By extending the 3D culture to 14 days, these blastoids mimic early gastrulation, demonstrating the specification and migration of cells. They also show the transcriptional signature of hemogenic angioblast (HAB) cells at Carnegie stage 6 (CS6). This model bridges pre- and post-implantation stages, offering valuable insights into early tissue formation and human development.

Humans↗
PubMed1978

Inhibition of putrescine synthesis blocks development of the polychete Ophryotrocha labronica at gastrulation.

Development eggs of the polychete Ophryotrocha labronica were analyzed for polyamines during the first 6 days after fertilization. The spermine content dominated initially, but gradually decreased. It was surpassed by putrescine, which rapidly increased to a maximum on the 3rd day, i.e., at the inception of grastrulation. The spermidine content was low during the entire period. Treatment of eggs with the putrescine synthesis inhibitor alpha-methylornithine from the onset of development led to developmental arrest at gastrulation and to an abnormally low content of putrescine in the treated embryos. Methylglyoxal bis(guanylhydrazone), an inhibitor of spermine and spermidine synthesis, had no visible effect of development. Our observations strongly suggest that putrescine synthesis is indispensable in early embryonic development of Ophryotrocha.

Animals↗
PubMed1978

Preparation of cell populations with stabilized erythropoietic potential from the primitive streak chick blastodisc: some implications for control of gastrulation.

Improved methods for preparation from primitive streak chick blastodiscs of cell suspensions capable of forming erythroid cells in culture have been developed. When blastodiscs were preincubayed with hyaluronidase in the absence of collagenase before cell dispersion and a high concentration of methyl-alpha-mannoside was present in all media, the yields of cells were some 10-fold higher than those obtained by former procedures. Cell suspensions obtained consisted almost entirely of viable cells, yielded large numbers of free mature erythrocytes in liquid culture, and formed erythroid colonies and bursts in solidified medium. The capacity to form differentiated cells after resedimenrtation through Ficoll density gradients was partly stabilized. Addition of gee yolk homogenate to the blastodiscs immediately following treatment with hyaluronidase and to all media used thereafter largely stabilized the capacity to form erythroid cells during resedimentation through Ficoll density gradients. Possible relevance of observations made during development of the procedures to the control of onset of cell migration in the process of gastrulation is indicated.

Animals↗
PubMed1977

[Structure of the morphogenetic movements of gastrulation in Anura. I. Destabilization of ooplasmic segregation and cleavage under the action of clinostatic rotation].

The yolk segregation in the developing Rana temporaria egg was studied both in vivo and under the effect of clinostate rotation, i. e. slow rotation around the horizontal axis imitating the state of weightlessness. From the moment of fertilization and during the whole period of cleavage the yolk was shown to subdivide succesively in distinct phases which differ by the characteristic value of yolk granules. During the normal development, in spite of the marked variability of form and mutual position of phases, the main elements of their animal-vegetative order are preserved. Under the effect of clinostate rotation the process of normal segregation becomes destabilized and variations in the egg structure are expressed by the beginning of gastrulation in the diversity of variants of distribution of the cellular material competent to different morphogenetic movements.

Amphibians↗
PubMed1977

[Induction of the mesoderm and primordial germ cells by the endoderm of Pleurodeles waltlii (Amphibia, Urodele): development during gastrulation].

Blastulae ectoderm is combined with dorsal or ventral endoderm from blastulae, gastrulae and early neurulae. In vitro culture reveals the presence of different mesodermal structures whose nature is connected with the endoderm origin site. Primordial germ cells differentiate essentially in the recombinates including ventral endoderm. The inducing capacity of this latter concerning germ cells is maximum at the beginning of gastrulation, then decreases during it and finally disappears at the onset of neurulation.

Age Factors↗
PubMed1979

[Proliferative activity and the kinetics of the cell populations of chick embryo blastoderm in the period of gastrulation and early organogenesis. I. The proliferative activity and nature of the transition by mitotic cycle cells].

The intensity of entry of cells of different rudiments of the chick embryo in mitosis and S-phase at the stages of gastrulation and early organogenesis was studied by means of statmokinetic method and thymidine autoradiography. Regular changes in the percentage of cells entering mitosis and S-phase during development were found. The fluctuations of one index do not coincide often with those of another. The values of these indices within the limits of one rudiment may be interrelated in different ways. These interrelations change in their turn from one stage to another. A suggestion is put forward to the effect that the regular changes found represent a form of expression of parasynchronous proliferation pattern, related to the regular changes of the composition of cell polations due to unequal pasage of cells through the mitotic cycle.

Animals↗
PubMed1977

[Consequence of heterospecific cytoplasmic graft on gastrulation of Bufo bufo L. (Amphibia, Anura)].

Bufo bufo nuclei were grafted in virgin and enucleated Bufo calamita eggs. In these conditions embryonnic development was stopped at the early gastrula stage in 92% of the recipient eggs. For accomparative analysis Bufo calamita cytoplasm was injected into fertilized Bufo bufo eggs and produce arrest of development at the early gastrula stage. The progressive enhancement of this development inhibition was related to the increasing of the injected cytoplasm volume.

Animals↗
PubMed1977

A fine-structural study of embryonic and larval development in the gymnoblastic hydroid Pennaria tiarella.

1. The pregastrulation blastomers contain electron-dense granules which become localized after gastrulation in the apices of the developing epithelio-muscle cells and persist throughout larval development. The cytoplasm of the blastomeres is organized into anucleate, membrane-delimited lobules. The lobules, which persist until six hours of development, come to contain a single, peripherally located cisterna of granular endoplasmic reticulum. Microvilli are present at the earliest stages examined and persist throughout development. Cilia are first detected at four hours. 2. Gastrulation, marked by the appearance of the mesoglea, occurs between six and eight hours of development. Basal foot processes of epithelio-muscle cells are detected by eight hours, but myonemes cannot be detected until later in development. 3. Immediately following gastrulation, mucous cells begin their differentiation from dividing cells located near the apex of the ectoderm. During their differentiation, the cells elongate toward the mesoglea. 4. By 16 hours post-fertilization, a third cell type can be detected in the ectoderm. The cell, which contains no granules, has an unusual cytoplasmic organization in which fused membranes divide the cytoplasm into parallel compartments containing a single cisterna of granular endoplasmic reticulum. 5. The findings of the present study are correlated with those of previous studies of development in Pennaria and other hydroids. The possible functional roles of the Type I granules, the cytoplasmic lobules, and the nongranular cell are discussed.

Animals↗
PubMed1979

Somitogenesis in amphibia. II. Origins in early embryogenesis of two factors involved in somite specification.

A somite pre-pattern is established shortly before visible segmentation. The pre-pattern results from the interaction of two components: a wave of cell behavioural change that passes along the axis, and, an underlying co-ordination of the cells that is the basis for their association into large somite-sized groupings. The evidence is derived from studies of the zones of abnormal segmentation that follow temperature shocks delivered between the neurula and tail-bud stages (Pearson & Elsdale, 1979). Temperature shock given earlier at the mid-gastrula stage is however ineffective in inducing abnormalities in somitogenesis. Shocks given before the mid-gastrula stage reveal a prior period of sensitivity stretching back into the blastula. Thus early and late sensitive periods can be defined separated by a short refactory period. Quite different patterns in the distribution of somite abnormalities characterize the results of shock during the two sensitive periods, suggesting different aetiologies. It is concluded that the wave of rapid cell change is set up early in embryogenesis during the blastula stage, and each cell of the prospective paraxial mesoderm carries a determination to change after a specific length of time, i.e. a countdown is set in each cell. As a result of the movements of gastrulation, the prospective paraxial mesoderm cells become laid out along the axis of the neurula in the order (antero-posterior sequence) in which they will change. The achievement of the correct redistribution of the cells depends crucially on the conservation of the sequence in the blastula by the maintenance of topological integrity throughout gastrulation. It is suggested that early shock disturbs gastrulation movements, causing some mixing up of the cells resulting in incoherence of the wavefront. Whereas early shocks are thus assumed to affect the wave, the evidence suggests that late shock undergoes co-ordination. It is concluded therefore that co-ordination is established later, after the refractory period, around the late gastrula stage.

Animals↗