Structure and developmental tendency of the dorsal marginal zone in the early amphibian gastrula

Development ◽  
1971 ◽  
Vol 25 (2) ◽  
pp. 263-276
Author(s):  
Nobushige Ikushima ◽  
Setsuko Maruyama
Keyword(s):  
Outer Layer ◽  
Marginal Zone ◽  
Kinetic Properties ◽  
Electron Microscopic ◽  
Structural Differences ◽  
Peripheral Surface ◽  
Early Gastrula ◽  
A Share

The peripheral surface of a fertilized, uncleaved egg is subdivided through cleavage and is allotted to constituent cells. This is called the primary surface. In an early morula a constituent cell has two kinds of surfaces: the primary surface, and the secondary surface, which does not participate in forming the periphery of the embryo. Electron-microscopic observations showed structural differences between the two surfaces. When the dorsal marginal zone of an early gastrula of Hynobius nebulosus is excised and immersed in Feldman's solution, the piece can easily be separated into two layers: the outer layer, whose constituent cells are given a share of the primary surface, and the inner layer, whose constituent cells are completely covered only by the secondary surface. Both an explanted piece of the outer layer and an intact double-layered piece show three kinds of movement: spreading, convergence followed by stretching, and spherical thickening. The inner layer is kinetically very inert, showing slight spreading and thickening. An explanted piece of the outer layer differentiates into axial mesodermal structures, while the inner layer does not. When a piece of either the inner or the outer layer is implanted in the blastocoel of another gastrula, it induces deuterencephalic and spino-caudal structures and seems to differentiate into axial mesodermal structures. Differences of kinetic properties and differentiation are considered to result from the fact that the outer layer has the primary surface, while the inner layer does not. Functional effects of the primary surface on the movement of tissues and differentiation are discussed.

BRIEF REPORT: Freeze-Cleaving of Red Cell Membranes in Paroxysmal Nocturnal Hemoglobinuria

Blood ◽  
1967 ◽  
Vol 30 (6) ◽  
pp. 785-791 ◽  
Author(s):  
RONALD S. WEINSTEIN ◽  
ROGER A. WILLIAMS
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Cell Membranes ◽  
Red Cells ◽  
Red Cell ◽  
Electron Microscopic ◽  
Structural Differences ◽  
Microscopic Studies ◽  
Red Cell Membranes

Abstract Electron microscopic studies on dried isolated red cell ghosts have been reported to show lesions associated with cell membranes in paroxysmal nocturnal hemoglobinuria (PNH). In this study, carbon-platinum replicas of membranes of freeze-cleaved, partially hydrated PNH red cells and isolated PNH cell ghosts failed to confirm the existence of these abnormalities. This suggests that the previously described lesions are the products of drying artifacts, although they may reflect hidden structural differences between PNH and normal red cell membranes.

scholarly journals Purification and properties of 2-aminoadipate: 2-oxoglutarate aminotransferase from bovine kidney

1989 ◽  
Vol 261 (3) ◽  
pp. 761-768 ◽  
Author(s):  
D R Deshmukh ◽  
S M Mungre
Keyword(s):  
Rat Kidney ◽  
Deae Cellulose ◽  
Dicarboxylic Acids ◽  
Structural Similarity ◽  
Appreciable Amount ◽  
Kinetic Properties ◽  
Bovine Kidney ◽  
Purification And Properties ◽  
Kidney Enzyme ◽  
Structural Differences

Previous studies with rat kidney preparations indicated that 2-aminoadipate aminotransferase (AadAT) and kynurenine aminotransferase (KAT) activities are properties of a single protein. We found that bovine kidney contains an appreciable amount of AadAT activity, but lacks KAT activity. AadAT from bovine and rat kidney extracts were purified to electrophoretic homogeneity. The purification procedure included fractionation with (NH1)2SO1, heat treatment, DEAE-cellulose chromatography and hydroxyapatite chromatography. Physical and kinetic properties, such as pH optima, Km for substrates, Mr, electrophoretic mobility and inhibition by dicarboxylic acids of bovine kidney AadAT, were similar to those of the rat kidney enzyme. However, bovine kidney AadAT differed from rat kidney AadAT in substrate specificity, amino acid composition and stability when stored. The titration curve of bovine kidney AadAT was also different from that of the rat kidney enzyme. The results suggest that bovine kidney AadAT may have some structural similarity to rat kidney AadAT and that the structural differences observed between the two enzymes may explain the absence of KAT activity in bovine kidney.

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.

A novel Xenopus mix-like gene milk involved in the control of the endomesodermal fates

Development ◽  
1998 ◽  
Vol 125 (14) ◽  
pp. 2577-2585 ◽  
Author(s):  
V. Ecochard ◽  
C. Cayrol ◽  
S. Rey ◽  
F. Foulquier ◽  
D. Caillol ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Ectopic Expression ◽  
Homeobox Gene ◽  
Early Response ◽  
Response Gene ◽  
Mesodermal Cell ◽  
Early Response Gene ◽  
Mesoderm Formation ◽  
Definition Of ◽  
Early Gastrula

Here we describe a novel Xenopus homeobox gene, milk, related by sequence homology and expression pattern to the vegetally expressed Mix.1. As is the case with Mix.1, milk is an immediate early response gene to the mesoderm inducer activin. milk is expressed at the early gastrula stage in the vegetal cells, fated to form endoderm, and in the marginal zone fated to form mesoderm. During gastrulation, expression of milk becomes progressively reduced in the involuting mesodermal cells but is retained in the endoderm, suggesting that it may play a key role in the definition of the endo-mesodermal boundary in the embryo. Overexpression of milk in the marginal zone blocks mesodermal cell involution, represses the expression of several mesodermal genes such as Xbra, goosecoid, Xvent-1 or Xpo and increases the expression of the endodermal gene, endodermin. In the dorsal marginal zone, overexpression of milk leads to a severe late phenotype including the absence of axial structures. Ectopic expression of milk in the animal hemisphere or in ectodermal explants induces a strong expression of endodermin. Taken together, we propose that milk plays a role in the correct patterning of the embryo by repressing mesoderm formation and promoting endoderm identity.

scholarly journals Meissner corpuscles and their spatially intermingled afferents underlie gentle touch perception

Science ◽  
2020 ◽  
Vol 368 (6497) ◽  
pp. eabb2751 ◽  
Author(s):  
Nicole L. Neubarth ◽  
Alan J. Emanuel ◽  
Yin Liu ◽  
Mark W. Springel ◽  
Annie Handler ◽  
...  
Keyword(s):  
Receptive Fields ◽  
Microscopic Analysis ◽  
Sensorimotor Control ◽  
Glabrous Skin ◽  
Kinetic Properties ◽  
Electron Microscopic ◽  
Force Sensitivity ◽  
Tactile Stimuli ◽  
Touch Perception ◽  
Lamellar Cell

Meissner corpuscles are mechanosensory end organs that densely occupy mammalian glabrous skin. We generated mice that selectively lacked Meissner corpuscles and found them to be deficient in both perceiving the gentlest detectable forces acting on glabrous skin and fine sensorimotor control. We found that Meissner corpuscles are innervated by two mechanoreceptor subtypes that exhibit distinct responses to tactile stimuli. The anatomical receptive fields of these two mechanoreceptor subtypes homotypically tile glabrous skin in a manner that is offset with respect to one another. Electron microscopic analysis of the two Meissner afferents within the corpuscle supports a model in which the extent of lamellar cell wrappings of mechanoreceptor endings determines their force sensitivity thresholds and kinetic properties.

Asci of the Pezizales. VII. The apical apparatus of Galiella rufa and Sarcosoma globosum: reevaluation of the suboperculate ascus

1980 ◽  
Vol 58 (11) ◽  
pp. 1235-1243 ◽  
Author(s):  
Don A. Samuelson ◽  
Gerald L. Benny ◽  
James W. Kimbrough
Keyword(s):  
Comparative Analysis ◽  
Outer Layer ◽  
Differential Staining ◽  
Staining Reaction ◽  
Electron Microscopic ◽  
Separate Type ◽  
Apparent Change

Light and electron microscopic examinations were made on asci of Galiella rufa and Sarcosoma globosum with emphasis on the development, cytochemistry, and morphology of the apical apparatus. Comparative analysis of the fresh and revived states of the apical apparatus in G. rufa demonstrated no apparent change in wall layering and only minor differences in staining reaction with silver methenamine. Ascal tips of both species were slightly thinner walled than the rest of the ascus and possessed bistratified outer layers. The external stratum of the outer layer was more pronounced and electron dense at the apex in S. globosum. Opercula were distinguished by a cytochemically localized zone of dehiscence in G. rufa and a differential staining of the internal stratum of the outer layer in S. globosum. The ascus tips of G. rufa and S. globosum were most similar to other members of the Sarcosomataceae. The apical apparatuses of the Sarcoscyphaceae differed substantially from those of the Sarcosomataceae and the rest of the Pezizales, constituting a separate type.

scholarly journals The epithelium of the dorsal marginal zone of Xenopus has organizer properties

Development ◽  
1992 ◽  
Vol 116 (4) ◽  
pp. 887-899 ◽  
Author(s):  
J. Shih ◽  
R. Keller
Keyword(s):  
Neural Tube ◽  
Marginal Zone ◽  
Tissue Differentiation ◽  
Host Cells ◽  
Mesoderm Induction ◽  
Epithelial Layer ◽  
Spemann Organizer ◽  
Deep Region ◽  
Early Gastrula ◽  
Axial Development

We have investigated the properties of the epithelial layer of the dorsal marginal zone (DMZ) of the Xenopus laevis early gastrula and found that it has inductive properties similar to those of the entire Spemann organizer. When grafts of the epithelial layer of the DMZ of early gastrulae labelled with fluorescein dextran were transplanted to the ventral sides of unlabelled host embryos, they induced secondary axes composed of notochord, somites and posterior neural tube. The organizer epithelium rescued embryos ventralized by UV irradiation, inducing notochord, somites and posterior neural tube in these embryos, while over 90% of ventralized controls showed no such structures. Combinations of organizer epithelium and ventral marginal zone (VMZ) in explants of the early gastrula resulted in convergence, extension and differentiation of dorsal mesodermal tissues, whereas similar recombinants of nonorganizer epithelium and the VMZ did none of these things. In all cases, the axial structures forming in response to epithelial grafts were composed of labelled graft and unlabelled host cells, indicating an induction by the organizer epithelium of dorsal, axial morphogenesis and tissue differentiation among mesodermal cells that otherwise showed non-axial development. Serial sectioning and scanning electron microscopy of control grafts shows that the epithelial organizer effect occurs in the absence of contaminating deep cells adhering to the epithelial grafts. However, labelled organizer epithelium grafted to the superficial cell layer contributed cells to deep mesodermal tissues, and organizer epithelium developed into mesodermal tissues when deliberately grafted into the deep region. This shows that these prospective endodermal epithelial cells are able to contribute to mesodermal, mesenchymal tissues when they move or are moved into the deep environment. These results suggest that in normal development, the endodermal epithelium may influence some aspects of the cell motility underlying the mediolateral intercalation (see Shih, J. and Keller, R. (1992) Development 116, 901–914), as well as the tissue differentiation of mesodermal cells. These results have implications for the analysis of mesoderm induction and for analysis of variations in the differentiation and morphogenetic function of the marginal zone in different species of amphibians.

scholarly journals The patterning and functioning of protrusive activity during convergence and extension of the Xenopus organiser

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 81-91 ◽  
Author(s):  
Ray Keller ◽  
John Shih ◽  
Carmen Domingo
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Marginal Zone ◽  
Tissue Differentiation ◽  
Tissue Interactions ◽  
Dorsal Mesoderm ◽  
Convergence And Extension ◽  
Early Gastrula ◽  
Ventral Explants ◽  
Anterior Posterior

We discuss the cellular basis and tissue interactions regulating convergence and extension of the vertebrate body axis in early embryogenesls of Xenopus. Convergence and extension occur in the dorsal mesoderm (prospective notochord and somite) and in the posterior nervous system (prospective hindbrain and spinal cord) by sequential cell intercalations. Several layers of cells intercalate to form a thinner, longer array (radial intercalation) and then cells intercalate in the mediolateral orientation to form a longer, narrower array (mediolateral intercalation). Fluorescence microscopy of labeled mesodermal cells in explants shows that protrusive activity is rapid and randomly directed until the midgastrula stage, when it slows and is restricted to the medial and lateral ends of the cells. This bipolar protrusive activity results in elongation, alignment and mediolateral intercalation of the cells. Mediolateral intercalation behavior (MIB) is expressed in an anterior-posterior and lateral-medial progression in the mesoderm. MIB is first expressed laterally in both somitic and notochordal mesoderm. From its lateral origins in each tissue, MIB progresses medially. If convergence does not bring the lateral boundaries of the tissues closer to the medial cells in the notochordal and somitic territories, these cells do not express MIB. Expression of tissue-specific markers follows and parallels the expression of MIB. These facts argue that MIB and some aspects of tissue differentiation are induced by signals emanating from the lateral boundaries of the tissue territories and that convergence must bring medial cells and boundaries closer together for these signals to be effective. Grafts of dorsal marginal zone epithelium to the ventral sides of other embryos, to ventral explants and to UV-ventralized embryos show that it has a role in organising convergence and extension, and dorsal tissue differentiation among deep mesodermal cells. Grafts of involuting marginal zone to animal cap tissue of the early gastrula shows that convergence and extension of the hindbrain-spinal cord are induced by planar signals from the involuting marginal zone.

A fate map of superficial and deep circumblastoporal cells in the early gastrula of Pleurodeles waltl

Development ◽  
1992 ◽  
Vol 114 (1) ◽  
pp. 135-146 ◽  
Author(s):  
M. Delarue ◽  
S. Sanchez ◽  
K.E. Johnson ◽  
T. Darribere ◽  
J.C. Boucaut
Keyword(s):  
Marginal Zone ◽  
Cell Lineage ◽  
Tail Bud ◽  
Fate Map ◽  
Pleurodeles Waltl ◽  
Early Gastrula

We have determined the fate of presumptive mesodermal cells in the early Pleurodeles waltl gastrula. We labeled all cells in a gastrula with RLDx cell lineage tracer and superficial cells with 125I and then grafted small pieces of the marginal zone orthotopically into unlabeled host embryos. Labeled progeny were identified in sectioned embryos at the tail bud stage. The use of double-labeled grafts allowed us to study the relative contributions by superficial and deep cells to different derivatives. We found that the presumptive regions are generally distributed according to classical fate maps for urodeles but that the boundaries between presumptive regions are indistinct, due to extensive intermingling between cells at the edges of grafted regions. We have shown that there is a high dorsal to low ventral gradient of mixing between superficial and deep cells.

Bmp-4 acts as a morphogen in dorsoventral mesoderm patterning in Xenopus

Development ◽  
1997 ◽  
Vol 124 (12) ◽  
pp. 2325-2334 ◽  
Author(s):  
R. Dosch ◽  
V. Gawantka ◽  
H. Delius ◽  
C. Blumenstock ◽  
C. Niehrs
Keyword(s):  
Gene Expression ◽  
Long Range ◽  
Marginal Zone ◽  
Cell Types ◽  
Dorsoventral Patterning ◽  
Mesodermal Cell ◽  
Amphibian Embryos ◽  
Mesoderm Patterning ◽  
Early Gastrula ◽  
Different Doses

The marginal zone is a ring of tissue that gives rise to a characteristic dorsoventral pattern of mesoderm in amphibian embryos. Bmp-4 is thought to play an important role in specifying ventral mesodermal fate. Here we show (1) that different doses of Bmp-4 are sufficient to pattern four distinct mesodermal cell types and to pattern gene expression in the early gastrula marginal zone into three domains, (2) that there is a graded requirement for a Bmp signal in mesodermal patterning, and (3) that Bmp-4 has long-range activity which can become graded in the marginal zone by the antagonizing action of noggin. The results argue that Bmp-4 acts as a morphogen in dorsoventral patterning of mesoderm.

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