Neural fold abnormalities induced in newt embryos by a carcinogen

1985 ◽  
Vol 63 (8) ◽  
pp. 1989-1990
Author(s):  
Panagiotis A. Tsonis
Keyword(s):  
Embryonic Development ◽  
Abnormal Development ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Animal Pole ◽  
Vegetal Pole ◽  
Neurula Stage

The effects of a carcinogen, N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), on newt embryonic development were studied. When embryos are treated with MNNG before the blastula stage, abnormal development occurs. The most prominent effect is that the hinder region of the egg–embryo (vegetal pole) does not participate in the development; thus, only one hemisphere (animal pole) of the egg develops. This phenomenon is evident at the gastrula stage and becomes even more apparent during the neurula stage.

Ultrastructural changes in the avian vitelline membrane during embryonic development

Development ◽  
1969 ◽  
Vol 21 (3) ◽  
pp. 467-484
Author(s):  
Cynthia Jensen
Keyword(s):  
Embryonic Development ◽  
Mechanical Strength ◽  
Dual Role ◽  
Early Embryonic Development ◽  
Ultrastructural Changes ◽  
Vitelline Membrane ◽  
Entire Surface ◽  
Animal Pole ◽  
The Third ◽  
Vegetal Pole

The vitelline (yolk) membrane of the avian egg plays a dual role during early embryonic development; it encloses the yolk and provides a substratum for expansion of the embryo (Fig. 1). Expansion appears to be dependent upon the movement of cells at the edge of the blastoderm which is intimately associated with the inner layer of the vitelline membrane (New, 1959; Bellairs, 1963). The blastoderm (embryonic plus extraembryonic cells) has almost covered the entire surface of the yolk by the third and fourth days of incubation, and when this stage has been reached the vitelline membrane ruptures over the embryo and slips toward the vegetal pole. Rupture of the membrane during development appears to be the consequence of a decrease in its mechanical strength (Moran, 1936), which changes most rapidly at the animal pole (over the embryo).

Larval Development of Cucumaria Elongata (Echinodermata: Holothuroidea)

1969 ◽  
Vol 49 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Fu-Shiang Chia ◽  
J. B. Buchanan
Keyword(s):  
Low Frequency ◽  
Abnormal Development ◽  
Blastula Stage ◽  
Cell Stage ◽  
Animal Pole ◽  
Pharyngeal Bulb ◽  
Jelly Coat ◽  
Deposit Feeders ◽  
Three Stages ◽  
Thin String

Cucutnaria elongata Düben & Koren, collected from the Northumberland coast in January 1968, was induced to spawn in the laboratory by raising the temperature. At spawning, the animal waved its pharyngeal bulb back and forth while a thin string of gametes was discharged. The freshly spawned eggs, surrounded by a jelly coat, were at the end of the second meiotic division and the size varies from 250 to 350 μ in diameter. Oocytes in the ovarian tubules can be grouped into three stages according to their size and other morphological features. Insemination of artificially recovered eggs resulted in only a very low frequency of abnormal development up to 8-cell stage. However, over 90% fertilization was achieved by insemination of the naturally shed eggs and the development was normal. The cleavage was holoblastic and radial type. The larva hatched at post blastula stage and swam freely with its animal pole upward. A doliolaria stage with four ciliary bands and pentactula stage with five primary tentacles subsequently developed. The planktonic life at temperature 9–11 °C ended on the ninth day after fertilization. Pentactula, up to 4 months old, live underneath the mud where they are deposit feeders. The primary tentacles bearing mucus glands in the form of papillae are important in both locomotion and feeding. An outline of chronology from fertilization up to 5 months old is presented.

scholarly journals Structural and ultrastructural analysis of embryonic development ofProchilodus lineatus(Valenciennes, 1836) (Characiforme; Prochilodontidae)

Zygote ◽  
2006 ◽  
Vol 14 (3) ◽  
pp. 217-229 ◽  
Author(s):  
Alexandre Ninhaus-Silveira ◽  
Fausto Foresti ◽  
Alexandre de Azevedo
Keyword(s):  
Embryonic Development ◽  
Larval Stage ◽  
Cleavage Pattern ◽  
Optic Vesicle ◽  
Gastrula Stage ◽  
Cleavage Stage ◽  
Blastula Stage ◽  
Prochilodus Lineatus ◽  
The Third ◽  
High Mitotic Activity

SummaryThis survey was performed to characterize the embryogenesis ofProchilodus lineatus. Seven stages of embryo development were identified – zygote, cleavage, blastula, gastrula, segmentation, larval and hatching – after a period of incubation of 22 h (24 °C) or 14 h (28 °C). The following cleavage pattern was identified: the first plane was vertical (2 blastomeres); the second was vertical and perpendicular to the first (4 blastomeres); the third was vertical and parallel to the first (4 × 2); the fourth cleavage was vertical and parallel to the second (4 × 4); the fifth was vertical and parallel to the first (4 × 8); and the sixth cleavage was horizontal (64 blastomeres). At the blastula stage (3.0–4.0 h (24 °C); 1.66–2.0 h (28 °C)) irregular spaces were detected and periblast structuring was initiated. At the gastrula stage (4.0–8.0 h (24 °C); 3.0–6.0 h (28 °C)) the epiboly, convergence and cell movements, as well as the formation of embryonic layers, had begun. The segmentation stage (10.0–15.0 h (24 °C); 7.0–10.0 h (28 °C)) was characterized by a rudimentary formation of organs and systems (somites, optic vesicle and intestinal delimitation). The embryo at the larval stage (16.0–21.0 h (24 °C); 11.0–13.0 h (28 °C)) showed a free tail, more than 25 somites, an optic vesicle and a ready-to-hatch larval shape. The blastomeres at cleavage stage had disorganized nuclei indicating high mitotic activity. At gastrula, the blastomeres and the periblast had euchromatic nuclei and a large number of mitochondria and vesicles. The yolk was organized into globose sacs, which were dispersed into small pieces prior to absorption.

scholarly journals Embryonic development of Peruvian grunt Anisotremus scapularis (Perciformes: Haemulidae)

2019 ◽  
Vol 54 (2) ◽  
pp. 166
Author(s):  
Melissa Montes ◽  
Angélica M. Castro ◽  
Joel F. Linares ◽  
Lucas I. Orihuela ◽  
Lili J. Carrera
Keyword(s):  
Embryonic Development ◽  
Marine Fish ◽  
Gastrula Stage ◽  
Morphometric Characteristics ◽  
Blastula Stage ◽  
First Report ◽  
Laboratory Conditions ◽  
Natural Spawning ◽  
Basic Biology ◽  
Newly Hatched Larvae

Peruvian grunt Anisotremus scapularis is distributed from Ecuador to Chile and it is considered an important aquaculture resource in Peru. Knowledge of embryonic development is crucial because it is part of the basic biology of a species. The aim of this study was to describe the embryonic stages of Peruvian grunt. The eggs were obtained by natural spawning and reared at 19 °C under laboratory conditions. Morphometric characteristics of the egg were evaluated: diameter (0.752 ± 0.025 mm) (mean ± sd) and oil globule diameter (0.165 ± 0.014 mm). The first division was observed approximately 45 min after fertilization. Blastula stage started after 4 h and the middle gastrula stage after 12:30 h. Early neurula was observed 17 h after fertilization. Cardiac beats and movements of the free embryonic tail were recorded after 30 h of incubation. Hatching occurred between 31 to 41 h and length of newly hatched larvae was 2.558 ± 0.051 mm. The embryonic development of this species is similar to previous studies regarding other marine fish. This study is the first report of embryonic development of A. scapularis, which is a valuable information that provide a baseline reference for the efforts for the culture of this species.

scholarly journals Embryonic development in the acoel Hofstenia miamia

2021 ◽  
Author(s):  
Julian O. Kimura ◽  
Lorenzo Ricci ◽  
Mansi Srivastava
Keyword(s):  
Embryonic Development ◽  
Transcriptome Data ◽  
Genetic Studies ◽  
Animal Pole ◽  
Cell Internalization ◽  
Vegetal Pole ◽  
Summary Statement ◽  
Marine Worms ◽  
Developmental Staging

AbstractAcoels are marine worms that belong to the phylum Xenacoelomorpha. The phylogenetic placement of this group as a deep-diverging lineage makes acoel embryos an attractive system to study the evolution of major bilaterian traits. Thus far, acoel development has not been described in detail at the morphological and transcriptomic levels in a species where functional genetic studies are possible. Here, we present a set of developmental landmarks for embryogenesis in the highly regenerative acoel Hofstenia miamia. We generated a developmental staging atlas from zygote to hatched worm based on gross morphology, with accompanying bulk transcriptome data for each of the stages. Hofstenia embryos undergo a stereotyped cleavage program known as duet cleavage, which results in two large ‘macromeres’ at the vegetal pole and numerous small ‘micromeres’ at the animal pole. The macromeres become internalized as micromere progeny proliferate and move vegetally, enveloping the larger blastomeres. We also noted a second, previously undescribed cell internalization event at the animal pole, following which we detected tissues corresponding to all three germ layers. Our work on Hofstenia embryos provides a resource for future investigations of acoel development, which will yield insights into the evolution of development and regeneration.Summary StatementComprehensive characterization of embryonic development in the acoel worm Hofstenia miamia with accompanying transcriptome data.

scholarly journals Embryonic development in the acoel Hofstenia miamia

Development ◽  
2021 ◽  
Vol 148 (13) ◽  
Author(s):  
Julian O. Kimura ◽  
Lorenzo Ricci ◽  
Mansi Srivastava
Keyword(s):  
Embryonic Development ◽  
Small Animal ◽  
Transcriptome Data ◽  
Genetic Studies ◽  
Germ Layers ◽  
Animal Pole ◽  
Cell Internalization ◽  
Vegetal Pole ◽  
Marine Worms ◽  
Developmental Staging

ABSTRACT Acoels are marine worms that belong to the phylum Xenacoelomorpha, a deep-diverging bilaterian lineage. This makes acoels an attractive system for studying the evolution of major bilaterian traits. Thus far, acoel development has not been described in detail at the morphological and transcriptomic levels in a species in which functional genetic studies are possible. We present a set of developmental landmarks for embryogenesis in the highly regenerative acoel Hofstenia miamia. We generated a developmental staging atlas from zygote to hatched worm based on gross morphology, with accompanying bulk transcriptome data. Hofstenia embryos undergo a stereotyped cleavage program known as duet cleavage, which results in two large vegetal pole ‘macromeres’ and numerous small animal pole ‘micromeres’. These macromeres become internalized as micromere progeny proliferate and move vegetally. We also noted a second, previously undescribed, cell-internalization event at the animal pole, following which we detected major body axes and tissues corresponding to all three germ layers. Our work on Hofstenia embryos provides a resource for mechanistic investigations of acoel development, which will yield insights into the evolution of bilaterian development and regeneration.

Expression of a novel FGF in the Xenopus embryo. A new candidate inducing factor for mesoderm formation and anteroposterior specification

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 711-720 ◽  
Author(s):  
H.V. Isaacs ◽  
D. Tannahill ◽  
J.M. Slack
Keyword(s):  
Specific Activity ◽  
Biological Properties ◽  
The Body ◽  
Mesoderm Induction ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Mesoderm Formation ◽  
Low Levels

We have cloned and sequenced a new member of the fibroblast growth factor family from Xenopus laevis embryo cDNA. It is most closely related to both mammalian kFGF (FGF-4) and FGF-6 but as it is not clear whether it is a true homologue of either of these genes we provisionally refer to it as XeFGF (Xenopus embryonic FGF). Two sequences were obtained, differing by 11% in derived amino acid sequence, which probably represent pseudotetraploid variants. Both the sequence and the behaviour of in vitro translated protein indicates that, unlike bFGF (FGF-2), XeFGF is a secreted molecule. Recombinant XeFGF protein has mesoderm-inducing activity with a specific activity similar to bFGF. XeFGF mRNA is expressed maternally and zygotically with a peak during the gastrula stage. Both probe protection and in situ hybridization showed that the zygotic expression is concentrated in the posterior of the body axis and later in the tailbud. Later domains of expression were found near the midbrain/hindbrain boundary and at low levels in the myotomes. Because of its biological properties and expression pattern, XeFGF is a good candidate for an inducing factor with possible roles both in mesoderm induction at the blastula stage and in the formation of the anteroposterior axis at the gastrula stage.

A functional test for maternally inherited cadherin in Xenopus shows its importance in cell adhesion at the blastula stage

Development ◽  
1994 ◽  
Vol 120 (1) ◽  
pp. 49-57 ◽  
Author(s):  
J. Heasman ◽  
D. Ginsberg ◽  
B. Geiger ◽  
K. Goldstone ◽  
T. Pratt ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Protein Level ◽  
Mrna Level ◽  
Functional Test ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Xenopus Development ◽  
Dose Dependent ◽  
Embryonic Ectoderm ◽  
E Cadherin

We report here on the consequences of reducing the expression of EP-cadherin at the earliest stages of Xenopus development. Injection of oligodeoxynucleotides antisense to maternal EP-cadherin mRNA into full-grown oocytes reduced the mRNA level in oocytes, and the protein level in blastulae. Adhesion between blastomeres was significantly reduced, as seen in whole embryos, and in assays of the ability of blastomeres to reaggregate in culture. This effect was especially conspicuous in the inner cells of the blastula and included the disruption of the blastocoel. The severity of the EP-cadherin mRNA depletion and of the disaggregation phenotype was dose dependent. This phenotype was rescued by the injection into EP-cadherin mRNA-depleted oocytes of the mRNA coding for a related cadherin, E-cadherin, that is normally expressed at the gastrula stage in the embryonic ectoderm.

Translocation of a store of maternal cytoplasmic c-myc protein into nuclei during early development

1989 ◽  
Vol 9 (12) ◽  
pp. 5395-5403
Author(s):  
M Gusse ◽  
J Ghysdael ◽  
G Evan ◽  
T Soussi ◽  
M Méchali
Keyword(s):  
Embryonic Development ◽  
Xenopus Laevis ◽  
Protein Content ◽  
Mature Oocyte ◽  
Gastrula Stage ◽  
Cleavage Stage ◽  
Midblastula Transition ◽  
Phosphorylation State ◽  
Growing Cell ◽  
Delayed Translation

The c-myc proto-oncogene is expressed as a maternal protein during oogenesis in Xenopus laevis, namely, in nondividing cells. A delayed translation of c-myc mRNA accumulated in early oocytes results in the accumulation of the protein during late oogenesis. The oocyte c-myc protein is unusually stable and is located in the cytoplasm, contrasting with its features in somatic cells. A mature oocyte contains a maternal c-myc protein stockpile of 4 x 10(5) to 6 x 10(5) times the level in a somatic growing cell. This level of c-myc protein is preserved only during the cleavage stage of the embryo. Fertilization triggers its rapid migration into the nuclei of the cleaving embryo and a change in the phosphorylation state of the protein. The c-myc protein content per nucleus decreases exponentially during the cleavage stage until a stoichiometric titration by the embryonic nuclei is reached during a 0.5-h period at the midblastula stage. Most of the maternal c-myc store is degraded by the gastrula stage. These observations implicate the participation of c-myc in the events linked to early embryonic development and the midblastula transition.

Muscle gene activation in Xenopus requires intercellular communication during gastrula as well as blastula stages

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 137-142 ◽  
Author(s):  
J. B. Gurdon ◽  
K. Kao ◽  
K. Kato ◽  
N. D. Hopwood
Keyword(s):  
Protein Synthesis ◽  
Developmental Stage ◽  
Cell Transplantation ◽  
Intercellular Communication ◽  
Gene Activation ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Morphological Marker ◽  
Muscle Gene ◽  
Early Gastrula

In Xenopus an early morphological marker of mesodermal induction is the elongation of the mesoderm at the early gastrula stage (Symes and Smith, 1987). We show here that the elongation of equatorial (marginal) tissue is dependent on protein synthesis in a mid blastula, but has become independent of it by the late blastula stage. In animal caps induced to become mesoderm, the time when protein synthesis is required for subsequent elongation immediately follows the time of induction, and is not related to developmental stage. For elongation, intercellular communication during the blastula stage is of primary importance. Current experiments involving cell transplantation indicate a need for further celhcell interactions during gastrulation, and therefore after the vegetal-animal induction during blastula stages. These secondary cell interactions are believed to take place among cells that have already received a vegetal induction, and may facilitate some of the later intracellular events known to accompany muscle gene activation.

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