scholarly journals WAVE OF STIFFNESS PROPAGATING ALONG THE SURFACE OF THE NEWT EGG DURING CLEAVAGE

1974 ◽  
Vol 60 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Tsuyoshi Sawai ◽  
Mitsuki Yoneda
Keyword(s):  
Cleavage Furrow ◽  
Animal Pole ◽  
High Stiffness ◽  
Triturus Pyrrhogaster

In the eggs of the newt, Cynops (Triturus) pyrrhogaster, change in stiffness of the cortex was measured in various regions at the time of the cleavage. Measurements were performed by Mitchison and Swann's cell elastimeter method with a modification, in which two fine pipettes were attached to the surface of one egg at the same time, in order to compare the rigidity of two regions. The stiffness of the cortex changed very little before the start of the first cleavage. However, just before the appearance of the first cleavage furrow, the stiffness increased rapidly at the animal pole region, which later returned to the former level. As the cleavage furrow progressed, a wave of high stiffness travelled meridionally as a belt along the surface from the animal pole region toward the vegetal region. At second cleavage, the cycle of change in stiffness was repeated.

Roles of Cortical and Subcortical Components in Cleavage Furrow Formation in Amphibia

1972 ◽  
Vol 11 (2) ◽  
pp. 543-556
Author(s):  
TSUYOSHI SAWAI
Keyword(s):  
Surface Layer ◽  
Xenopus Laevis ◽  
Species Specificity ◽  
Cleavage Furrow ◽  
Entire Surface ◽  
Animal Pole ◽  
The Future ◽  
Vegetal Pole ◽  
Triturus Pyrrhogaster

In the eggs of the newt, Triturus pyrrhogaster, 2 separate factors are recognized which take part in cleavage furrow formation. (1) The inductive capacity for the furrow formation by the cytoplasm lying under the cortex along the cleavage furrow (FIC); and (2) the reactivity of the overlying cortex to form a furrow in response to FIC. (1) FIC. The inductive capacity is shown by the fact that FIC induces a furrow on whichever part of the surface under which FIC is transplanted. FIC is distributed along the cleavage furrow and even extends along the future furrow plane ahead of the furrow tip. The distance FIC precedes the furrow tip is about 1.0 mm in the animal hemisphere and is less in the vegetal hemisphere. In the direction at right angles to the furrow plane, FIC does not spread more than 0.1 mm. FIC is also present in the eggs of Xenopus laevis. Species specificity of FIC for induction is not found between Triturus and Xenopus. (2) Surface layer. At the onset of the first cleavage, the reactivity of the cortex to form the furrow in answer to FIC induction is localized on the animal pole region. The reactivity of the cortex propagates medially as a belt along the surface towards the vegetal pole with the advancing tip of the cleavage furrow. After the furrow is completed, the reactivity begins to be lost from the animal pole region, and eventually over the entire surface. The reactivity, however, reappears on the animal pole region simultaneously with the second cleavage.

Studies of the cleavage in the frog egg

Development ◽  
1969 ◽  
Vol 21 (1) ◽  
pp. 119-129
Author(s):  
T. Kubota
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Cleavage Furrow ◽  
Mitotic Apparatus ◽  
Animal Pole ◽  
Sea Urchin Eggs ◽  
Rana Nigromaculata ◽  
Vegetal Pole ◽  
Egg Cortex

In sea-urchin eggs, once karyokinesis reaches metaphase or anaphase, the cleavage furrow can be formed even if the mitotic apparatus is destroyed (Swann & Mitchison, 1953) or removed (Hiramoto, 1956). A similar result was obtained in frog eggs (Kubota, 1966). In amphibian eggs a much longer time is available for performing experiments than in sea urchins as the furrow first appears at the animal pole and slowly travels toward the vegetal pole. Taking advantage of this situation, Waddington (1952) and Dan & Kuno-Kojima (1963) performed various kinds of operations to elucidate the roles of the egg cortex and the inner cytoplasm in furrow formation, and Selman & Waddington (1955) also made cytological observations of the process. In the present paper a shift of the inner cytoplasm relative to the cortex and its influence on the course of the furrow was analysed for eggs of the frog Rana nigromaculata.

scholarly journals Membrane protein redistribution during Xenopus first cleavage.

1986 ◽  
Vol 102 (6) ◽  
pp. 2176-2184 ◽  
Author(s):  
T J Byers ◽  
P B Armstrong
Keyword(s):  
Leading Edge ◽  
Surface Proteins ◽  
Cleavage Furrow ◽  
Initial Surface ◽  
Contractile Ring ◽  
Animal Pole ◽  
Amphibian Embryo ◽  
Carbon Particles ◽  
Later Phase ◽  
Xenopus Laevis Embryos

A large increase in surface area must accompany formation of the amphibian embryo first cleavage furrow. The additional membrane for this areal expansion has been thought to be provided entirely from cytoplasmic stores during furrowing. We have radioiodinated surface proteins of fertilized, precleavage Xenopus laevis embryos and followed their redistribution during first cleavage by autoradiography. Near the end of first cleavage, membrane of the outer, pigmented surface of the embryo and a short band of membrane at the leading edge of the furrow displayed a high silver grain density, but the remainder of the furrow membrane was lightly labeled. The membrane of the cleavage furrow is thus mosaic in character; the membrane at the leading edge originates in part from the surface of the zygote, but most of the membrane lining the furrow walls is derived from a source inaccessible to surface radioiodination. The furrow membrane adjacent to the outer, pigmented surface consistently showed a very low silver grain density and was underlain by large membranous vesicles, suggesting that new membrane derived from cytoplasmic precursors is inserted primarily in this location, at least during the later phase of cleavage. Radioiodinated membrane proteins and surface-attached carbon particles, which lie in the path of the future furrow, contract toward the animal pole in the initial stages of cleavage while markers in other regions do not. We suggest that the domain of heavily labeled membrane at the leading edge of the definitive furrow contains the labeled elements that are gathered at the animal pole during the initial surface contraction and that they include membrane anchors for the underlying contractile ring of microfilaments.

On ‘the Stationary Surface Ring’ in Heart-Shaped Cleavage

1958 ◽  
Vol 35 (2) ◽  
pp. 400-406
Author(s):  
KATSUMA DAN
Keyword(s):  
Cell Surface ◽  
Sea Urchin ◽  
Mitotic Spindle ◽  
Cleavage Furrow ◽  
Sand Dollar ◽  
Animal Pole ◽  
Sea Urchin Eggs ◽  
Stationary Surface ◽  
Vegetal Pole

1. The eggs of the sand dollar, Astriclypeus manni, and the medusa, Spirocodon saltatrix, were used for the reason that they cleave in heart shape, the cleavage furrow appearing earlier at the animal than at the vegetal pole. 2. By the superposition of drawings showing contours and astral centres as well as the positions of carbon markers on the cell surface, the presence of a pair of stationary circular zones of the cortex can be demonstrated. These remain absolutely stationary through successive stages of cleavage, as was shown to be true of regularly cleaving sea-urchin eggs. 3. The two planes determined by this pair of stationary surface rings tilt toward each other on the animal pole side in linear proportion to the eccentricity of the mitotic spindle within the cell, and the loci of the astral centres tend to slant toward the animal pole. 4. The above phenomena can be explained by the previously proposed theory for heart-shaped cleavage; i.e. the primary cause of heart-shaped cleavage is the eccentric position of the spindle, which in turn causes the rotation of the asters and the bending of the spindle.

A Study on the Mechanism of Cleavage in the Amphibian Egg

1963 ◽  
Vol 40 (1) ◽  
pp. 7-14
Author(s):  
K. DAN ◽  
M. KUNO KOJIMA
Keyword(s):  
Cleavage Furrow ◽  
Straight Line ◽  
Triturus Pyrrhogaster

1. In the eggs of the salamander, Triturus pyrrhogaster, there is an area extending about 1 mm. ahead of the advancing tip of the cleavage furrow where preparation for furrow formation is going on. 2. Severance of this area ahead of an advancing furrow tip does not stop the progress of the furrow. The furrow continues from this area. 3. The cleavage furrow of Triturus pyrrhogaster eggs advances strictly along a straight line. 4. A cut made across its path ahead of a furrow is healed as the furrow tip approaches sufficiently to allow its straight passage. 5. An excised piece of cortex which includes material taken from within 1 mm. of an advancing furrow tip will form a furrow and divide.

NJZ ALLOY No. 55

Alloy Digest ◽  
1976 ◽  
Vol 25 (12) ◽  
Keyword(s):  
Tensile Strength ◽  
Corrosion Resistance ◽  
New Jersey ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
High Tensile Strength ◽  
High Stiffness ◽  
Zinc Cadmium ◽  
Forming Characteristics

Abstract NJZ Alloy No. 55 is a zinc-cadmium alloy characterized by high tensile strength and hardness but low ductility. It has high stiffness and resiliency but low drawing and forming characteristics. Its applications include hardware and medallions. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as creep and fatigue. It also includes information on corrosion resistance as well as casting, forming, heat treating, machining, and joining. Filing Code: Zn-30. Producer or source: New Jersey Zinc Company.

NJZ ALLOY No. 45

Alloy Digest ◽  
1976 ◽  
Vol 25 (1) ◽  
Keyword(s):  
Corrosion Resistance ◽  
New Jersey ◽  
Physical Properties ◽  
Tensile Properties ◽  
Copper Alloy ◽  
High Hardness ◽  
Heat Treating ◽  
Good Ductility ◽  
High Stiffness

Abstract NJZ Alloy No. 45 is a zinc-copper alloy characterized by high hardness and strength, good ductility and high stiffness. It work hardens easily. Among its many applications are hardware, sporting-equipment components, cable wrappings and watch cases. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as creep and fatigue. It also includes information on corrosion resistance as well as casting, forming, heat treating, machining, and joining. Filing Code: Zn-25. Producer or source: New Jersey Zinc Company.

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