scholarly journals Lithium changes the ectodermal fate of individual frog blastomeres because it causes ectopic neural plate formation

Development ◽  
1989 ◽  
Vol 106 (3) ◽  
pp. 599-610
Author(s):  
S.L. Klein ◽  
S.A. Moody
Keyword(s):  
Neural Plate ◽  
Early Cleavage ◽  
Ventral Midline ◽  
Plate Formation ◽  
Form Part ◽  
Cleavage Stages ◽  
Midline Cells ◽  
The Brain ◽  
Brain Examination ◽  
Developmental Window

Amphibian blastulae that are treated with lithium (Li) develop into embryos that consist almost exclusively of head structures. This dramatic change in embryogenesis may occur either because Li selectively kills trunk progenitors or because Li causes trunk progenitors to become head progenitors. To distinguish between these possibilities, we compared the fates of individual frog blastomeres between Li-treated embryos and normal embryos using lineage tracers. The results demonstrate that Li causes ventral midline cells, which normally populate large amounts of trunk, to produce many head structures, including the brain. Examination of fluorescently labeled clones in living Li-treated gastrulae shows that: (1) the ectodermal members of the clones migrate normally, and chordamesodermal involution begins normally; (2) the chordamesoderm's later involution is altered such that it is confined to the vegetal hemisphere; (3) accordingly, the neural plate forms in the vegetal hemisphere, circumscribing the blastopore, which normally gives rise to the cloaca; and (4) the ectodermal progeny of the ventral midline blastomeres that are near the blastopore populate the brain because they are induced by the stalled chordamesoderm to form part of the ectopic neural plate. These results demonstrate that Li, administered during a short developmental window at early cleavage stages, ultimately alters ectodermal fate because it changes the pattern of chordamesodermal involution during gastrulation, which in turn changes the site of neural plate formation.

scholarly journals Differential patterning of ventral midline cells by axial mesoderm is regulated by BMP7 and chordin

Development ◽  
1999 ◽  
Vol 126 (2) ◽  
pp. 397-408 ◽  
Author(s):  
K. Dale ◽  
N. Sattar ◽  
J. Heemskerk ◽  
J.D. Clarke ◽  
M. Placzek ◽  
...  
Keyword(s):  
Sonic Hedgehog ◽  
Floor Plate ◽  
Neural Plate ◽  
Ventral Midline ◽  
Molecular Events ◽  
Morphogenetic Protein ◽  
Explant Cultures ◽  
Prechordal Mesoderm ◽  
Midline Cells ◽  
Bmp Antagonist

Ventral midline cells in the neural tube have distinct properties at different rostrocaudal levels, apparently in response to differential signalling by axial mesoderm. Floor plate cells are induced by sonic hedgehog (SHH) secreted from the notochord whereas ventral midline cells of the rostral diencephalon (RDVM cells) appear to be induced by the dual actions of SHH and bone morphogenetic protein 7 (BMP7) from prechordal mesoderm. We have examined the cellular and molecular events that govern the program of differentiation of RDVM cells under the influence of the axial mesoderm. By fate mapping, we show that prospective RDVM cells migrate rostrally within the neural plate, passing over rostral notochord before establishing register with prechordal mesoderm at stage 7. Despite the co-expression of SHH and BMP7 by rostral notochord, prospective RDVM cells appear to be specified initially as caudal ventral midline neurectodermal cells and to acquire RDVM properties only at stage 7. We provide evidence that the signalling properties of axial mesoderm over this period are regulated by the BMP antagonist, chordin. Chordin is expressed throughout the axial mesoderm as it extends, but is downregulated in prechordal mesoderm coincident with the onset of RDVM cell differentiation. Addition of chordin to conjugate explant cultures of prechordal mesoderm and neural tissue prevents the rostralization of ventral midline cells by prechordal mesoderm. Chordin may thus act to refine the patterning of the ventral midline along the rostrocaudal axis.

Spatial and developmental changes in the respiratory activity of mitochondria in early Drosophila embryos

Development ◽  
1992 ◽  
Vol 115 (4) ◽  
pp. 1175-1182 ◽  
Author(s):  
T. Akiyama ◽  
M. Okada
Keyword(s):  
Respiratory Activity ◽  
Cell Formation ◽  
Rhodamine 123 ◽  
Mitochondrial Activity ◽  
Early Cleavage ◽  
Pole Cell ◽  
Posterior Group ◽  
Cleavage Stages ◽  
Pole Cells ◽  
Drosophila Embryos

Mitochondria of early Drosophila embryos were observed with a transmission electron microscope and a fluorescent microscope after vital staining with rhodamine 123, which accumulates only in active mitochondria. Rhodamine 123 accumulated particularly in the posterior pole region in early cleavage embryos, whereas the spatial distribution of mitochondria in an embryo was uniform throughout cleavage stages. In late cleavage stages, the dye showed very weak and uniform accumulation in all regions of periplasm. Polar plasm, sequestered in pole cells, restored the ability to accumulate the dye. Therefore, it is concluded that the respiratory activity of mitochondria is higher in the polar plasm than in the other regions of periplasm in early embryos, and this changes during development. The temporal changes in rhodamine 123-staining of polar plasm were not affected by u.v. irradiation at the posterior of early cleavage embryos at a sufficient dosage to prevent pole cell formation. This suggests that the inhibition of pole cell formation by u.v. irradiation is not due to the inactivation of the respiratory activities of mitochondria. In addition, we found that the anterior of Bicaudal-D mutant embryos at cleavage stage was stained with rhodamine 123 with the same intensity as the posterior of wild-type embryos. No pole cells form in the anterior of Bic-D embryos, where no restoration of mitochondrial activity occurs in the blastoderm stage. The posterior group mutations that we tested (staufen, oskar, tudor, nanos) and the terminal mutation (torso) did not alter staining pattern of the posterior with rhodamine 123.

A study of the properties, morphogenetic potencies and prospective fate of outer and inner layers of ectodermal and chordamesodermal regions during gastrulation, in various Anuran amphibians

Development ◽  
1983 ◽  
Vol 75 (1) ◽  
pp. 67-86
Author(s):  
T. A. Dettlaff
Keyword(s):  
Outer Layer ◽  
Normal Development ◽  
Neural Plate ◽  
Ependymal Cells ◽  
Epithelial Layer ◽  
Bombina Bombina ◽  
Cell Layers ◽  
The Brain ◽  
Early Gastrula

In both the ectodermal and the chordamesodermal regions of Anuran embryos, the outer layer of cells possesses epithelial properties and has the same restricted morphogenetic potencies. It is thus interchangeable between the regions, capable of epiboly and, when underlain by notochord material, of the formation of bottle-shaped cells as at the blastoporal groove, and invagination. When taken from the chordamesoderm region, this outer layer has no inducing effect on the ectoderm of the early gastrula. In normal development the outer layer of the neural plate takes an active part in forming the neural tube cavity. It gives rise to the neuroepithelial roof of the diencephalon and medulla oblongata and, when underlain by neuroblasts that develop from the inner cell layers, to ependymal cells of the brain wall. The outer layer of the notochord material is included in the epithelial layer underlying the roof of the gastrocoel - the hypochordal plate. The inner layers of these regions consist of loosely arranged cells and normally have no epithelial properties although, when taken from the ectoderm region, they may acquire such properties upon long-term contact with the environment. However they have wide morphogenetic potencies; the differences in these potencies between cells taken from the various presumptive regions being less than the differences between outer and inner cell layers in each region. Maps are provided which show the arrangement of presumptive rudiments in the ectoderm and chordamesoderm on sagittal sections through Bombina bombina embryos in early and late gastrulation.

Incorporation of Uridine in Cleavage Stage Eggs of the Sea Urchin Paracentrotus Lividus

1971 ◽  
Vol 26 (8) ◽  
pp. 816-821 ◽  
Author(s):  
Larry E. Bockstahler
Keyword(s):  
Ion Exchange ◽  
Sea Urchin ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Paracentrotus Lividus ◽  
Cleavage Stage ◽  
Early Cleavage ◽  
Cell Stage ◽  
Cleavage Stages ◽  
Layer Chromatography

Incorporation of uridine in cleavage stage eggs of the sea urchin Paracentrotus lividus was investigated. It was shown by ion exchange and thin layer chromatography that most of the uridine taken up during the 16-cell stage was converted into UTP with some incorporation into UDP and UMP. Conversion of uridine to these phosphorylated nucleosides occurred throughout early cleavage stages. A very small amount of uridine taken up by cleavage stage eggs is incorporated into RNA heterogeneous in size. This RNA was examined by polyacrylamide gel electrophoresis.

X-ray Inactivation of Nuclei as a Method for Studying their Function in the Early Development of Fishes

Development ◽  
1959 ◽  
Vol 7 (2) ◽  
pp. 173-192
Author(s):  
A. A. Neyfakh
Keyword(s):  
Ionizing Radiation ◽  
Early Development ◽  
Nuclear Region ◽  
Blastula Stage ◽  
Early Cleavage ◽  
X Ray ◽  
Male Nucleus ◽  
Cleavage Stages ◽  
Heavy Dose

It is generally accepted at present that during cleavage in echinoderms, amphibians, and fishes, the nuclei do not have specific functions in regulating development, their role being at this time restricted to participation in the processes of cleavage (Schechtman & Nishihara, 1955). Eggs devoid of nuclei sometimes begin cleavage which may proceed up to the stage of the late blastula. Extirpation or inactivation of nuclei may be achieved through the separation of the nuclear region of the egg by means of centrifugation (Harvey, 1940); through extirpation of the female nucleus followed by fertilization with sperm inactivated by a heavy dose of radiation (Briggs, Green, & King, 1951); through spontaneous degeneration of the male nucleus during artificial androgenesis (Stauffer, 1945); and by means of other techniques. Exposure of early cleavage stages in amphibians (Mangold & Peters, 1956; Sanides, 1956) and fishes (Neyfakh, 1956a) to heavy doses of ionizing radiation also leads to arrest of development at the late blastula stage.

Brain Development and the Risk for Substance Abuse

2013 ◽  
pp. 706-715
Author(s):  
Kristina Caudle ◽  
B.J. Casey
Keyword(s):  
Substance Abuse ◽  
Substance Use ◽  
Brain Development ◽  
Substance Use Disorders ◽  
Animal Studies ◽  
Substance Abuse Problem ◽  
Increased Risk ◽  
Drug And Alcohol ◽  
The Brain ◽  
Developmental Window

Drug and alcohol dependence affects millions each year. Adolescence is a period of increased risk for substance use disorders. Understanding how the brain is changing during this developmental window relative to childhood and adulthood and how these changes vary across individuals is critical for predicting risk of later substance abuse and dependence. This chapter provides an overview of recent human imaging and animal studies of brain development focusing on changes in corticostriatal circuitry that has been implicated in addiction. Behavioral, clinical, and neurobiological evidence is provided to help elucidate who may be most at risk for developing a substance abuse problem and whenthey may be most vulnerable.

Neurodevelopment

2020 ◽  
pp. 91-100
Author(s):  
Karl Zilles ◽  
Nicola Palomero-Gallagher
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Neural Tube ◽  
Neural Plate ◽  
Adult Brain ◽  
The Central Nervous System ◽  
Specialized Region ◽  
The Brain ◽  
Rostral Part ◽  
Human Nervous System

The pre- and post-natal development of the human nervous system is briefly described, with special emphasis on the brain, particularly the cerebral and cerebellar cortices. The central nervous system originates from a specialized region of the ectoderm—the neural plate—which develops into the neural tube. The rostral part of the neural tube forms the adult brain, whereas the caudal part (behind the fifth somite) differentiates into the spinal cord. The embryonic brain has three vesicular enlargements: the forebrain, the midbrain, and the hindbrain. The histogenesis of the spinal cord, hindbrain, cerebellum, and cerebral cortex, including myelination, is discussed. The chapter closes with a description of the development of the hemispheric shape and the formation of gyri.

73 APPLICATION OF THE HOLLOW FIBER VITRIFICATION METHOD TO THE CRYOPRESERVATION OF HIGHLY CRYOSENSITIVE EMBRYOS

2015 ◽  
Vol 27 (1) ◽  
pp. 129 ◽  
Author(s):  
A. Uchikura ◽  
H. Matsunari ◽  
K. Nakano ◽  
S. Hatae ◽  
Y. Matsumura ◽  
...  
Keyword(s):  
Early Stage ◽  
Hollow Fibre ◽  
Membrane Thickness ◽  
Early Cleavage ◽  
Diverse Species ◽  
Organ Regeneration ◽  
Cleavage Stages ◽  
Vitro Development ◽  
Technological Options

We recently demonstrated that the hollow fibre vitrification (HFV) method (Matsunari et al. 2012) could effectively be applied to the cryopreservation of embryos from diverse species. In this study, we applied the HFV method to the cryopreservation of highly cryosensitive specimens, such as in vitro matured (IVM)/IVF-derived porcine zona-free morulae and blastomeres isolated from those morulae, as well as IVM/IVF-derived cattle embryos at early cleavage stages. Porcine parthenogenetic morulae (d-4) derived from IVM oocytes were treated with 0.25% pronase to remove zona pellucidae. The resulting blastomeres were isolated from the zona-free morulae by a decompaction treatment followed by gentle pipetting. Bovine IVM-IVF embryos at the 2 to 4 cell (d-1), 8 to 16 cell (d-3), and morula stages (d-5) were then subjected to vitrification. The HFV procedure was performed as described previously using 15% dimethyl sulfoxide, 15% ethylene glycol, and 0.5 M trehalose as cryoprotectants. Four to twenty embryos, or all of the blastomeres isolated from a single morula, were individually loaded into a cellulose acetate hollow fibre (25 mm long, 185 μm φ, 15 μm membrane thickness) and vitrified. Survival of the vitrified embryos was assessed by in vitro development to blastocysts. Blastomeres recovered after vitrification were aggregated in micro-wells to examine their ability to form blastocysts. The HFV method was demonstrated to be effective for cryopreserving zona-free in vitro-produced porcine morulae and the blastomeres isolated from them (Table 1), as well as bovine IVM-IVF embryos at early cleavage stages. These data demonstrate that the HFV method is effective for highly cryosensitive specimens, such as IVM/IVF-derived porcine zona-free morulae and blastomeres isolated from those morulae, and IVM/IVF-derived cattle embryos at early cleavage stages. These achievements may expand the technological options in the production of cloned and genetically modified pigs that are useful for biomedical research. Table 1.Survival of zona-free porcine morulae and isolated blastomeres after vitrification (top) and blastocyst formation rates in bovine early-stage in vitro matured-IVF embryos after vitrification (bottom) This study was supported by JST, ERATO, the Nakauchi Stem Cell and Organ Regeneration Project, and MUIIBR.

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