scholarly journals The Block to Polyspermy in Sturgeon and Trout with Special Reference to the Role of Cortical Granules (Alveoli)

Development ◽  
1961 ◽  
Vol 9 (1) ◽  
pp. 173-190
Author(s):  
A. S. Ginsburg
Keyword(s):  
Sea Urchins ◽  
Morphological Changes ◽  
Cortical Layer ◽  
Vitelline Membrane ◽  
Cortical Granules ◽  
Sea Urchin Egg ◽  
Protective Reaction ◽  
Fertilization Membrane ◽  
The Subject

When a monospermic egg is fertilized, the attachment of the fertilizing spermatozoon to the egg surface provokes a protective reaction that prevents all ut one spermatozoon from entering the egg; this is the block to polyspermy. The nature of the defence mechanism against polyspermy has been the subject of many investigations, performed mainly on the eggs of sea urchins. It was established that on fertilization of the sea-urchin egg a cortical reaction takes place consisting of morphological changes in the cortical layer, spreading in wave-like fashion from the point of the spermatozoon attachment over the whole egg surface: the light scattering and the intensity of birefringence undergo changes; extrusion of mucopolysaccharide granules takes place, accompanied by the separation of the vitelline membrane and its transformation into the fertilization membrane; the perivitelline space appears and the hyaline layer is then formed at the egg surface (see Runnström, 1952; Rothschild, 1956; Allen, 1958).

Example: Early Pattern Formation in Amphibia

1988 ◽  
Author(s):  
Keith Stewart Thomson
Keyword(s):  
Pattern Formation ◽  
Early Development ◽  
Sea Urchins ◽  
Vitelline Membrane ◽  
Causal Processes ◽  
Phases Of Development ◽  
Primary Induction ◽  
The Subject ◽  
Axis Of Symmetry ◽  
Early Phases

The Amphibia has been one of the most important animal groups for the study of developmental biology, and a huge descriptive and experimental literature has accumulated over the years. While sea urchins, molluscs, and nematodes, and more recently, Drosophila, have each become an important vehicle for the study of different aspects of development, the Amphibia and chordates in general have been especially important as the vehicle for the study of inductive regulative mechanisms. The early development of all chordates is marked by two revolutions in the control of early pattern formation: dorsalization at the blastula stage and gastrulation—primary induction caused by the “organizer” —which was studied in great detail in Amphibia by Spemann and his coworkers and continues to be the subject of intense scrutiny. The early phases of development in Amphibia exemplify rather well some of the problems in discovering the causal processes in development, whether in the egg, at fertilization, in the blastula, or in gastrulation itself. The short discussion of early development in Amphibia that follows is meant to exemplify rather than catalogue these questions. The oocyte in amphibians is radially symmetrical. A first axis of symmetry is established between a more heavily pigmented animal hemisphere and a less pigmented vegetal hemisphere. Before fertilization the egg is covered with a transparent vitelline membrane. When fertilization occurs, the vitelline membrane lifts from the surface of the egg and the egg is then free to rotate inside it so that the animal hemisphere lies uppermost and the vegetal hemisphere is lowermost. This rotation is apparently a response to gravity, which means that the vegetal hemisphere is heavier, almost certainly a result of the concentration of more and larger yolk granules in the vegetal hemisphere. Therefore, if the egg rotates to a new orientation with the yolk down and the animal hemisphere up, it must be the case that at this point the yolk and other egg contents are not free to be redistributed within the egg but are secured in place. The animal vegetal axis now marks the future anteroposterior axis of the embryo.

scholarly journals A COMPARATIVE STUDY OF THE ISOLATION OF THE CORTEX AND THE ROLE OF THE CALCIUM-INSOLUBLE PROTEIN IN SEVERAL SPECIES OF SEA URCHIN EGG

1969 ◽  
Vol 41 (1) ◽  
pp. 133-144 ◽  
Author(s):  
R. E. Kane ◽  
R. E. Stephens
Keyword(s):  
Comparative Study ◽  
Sea Urchin ◽  
Protein Composition ◽  
Cortical Region ◽  
Cortical Granules ◽  
Divalent Ions ◽  
Sea Urchin Egg ◽  
Protein Gelation ◽  
Isolated Cortex

A comparative study was made of the isolation of the cortex in the eggs of several sea urchin species. Since the isolation method developed by Sakai depends on the presence of magnesium in the medium, the protein composition of the cortex was investigated to determine whether the protein component of the egg described by Kane and Hersh which is gelled by divalent ions, is present in these cortices. Isolation of the cortex was found to require the same divalent ions at the same concentrations as protein gelation, and in the eggs of some species much of the gel protein of the cell was found in the isolated cortical material. In the eggs of other species a smaller fraction of this protein was found in the isolated cortex, although it was more concentrated there than in the endoplasm, and in one species this protein appeared to be uniformly distributed throughout the cell. These results indicate that this protein is localized in the cortical region of the eggs of some species of sea urchin, possibly in the cortical granules, but also point up the fact that results from one species cannot be uncritically extrapolated to others.

Isolated Plasma Membranes of Sea Urchin Eggs

1971 ◽  
Vol 29 ◽  
pp. 534-535
Author(s):  
S. Inoue ◽  
E. C. Preddie ◽  
P. Guerrier
Keyword(s):  
Electron Microscope ◽  
Sea Urchin ◽  
Plasma Membranes ◽  
Membrane System ◽  
Vitelline Membrane ◽  
Thin Sections ◽  
Sea Urchin Eggs ◽  
Sea Urchin Egg ◽  
Discontinuous Sucrose Gradient ◽  
Fertilization Membrane

From electron microscope studies of thin sections the sea urchin egg is known to be surrounded by the peripheral membrane system which is made up of the outer coat (vitelline membrane), which elevates from an egg surface after fertilization and becomes a part of the fertilization membrane, and the plasma membrane. In these experiments an effort has been made to isolate plasma membranes of sea urchin eggs and these isolated membranes were observed in the electron microscope.The vitelline membrane of the eggs from the sea urchin Strongylocentrotus purpuratus was at first digested away by the treatment with 0.02% trypsin in 0.01 M Tris-HCl buffer (pH 8.0) for 5 minutes at 28°C. The plasma membranes were then isolated according to the method of Song et al. which was used for the isolation of rat liver plasma membranes. The vitelline membrane-free eggs were gently homogenized in 10-3 M NaHC03 (pH 7.5) and freed membranes were collected by centrifugation over a discontinuous sucrose gradient preparation.

scholarly journals The Cortical Changes on Fertilization of the Sea-Urchin Egg

1955 ◽  
Vol 32 (3) ◽  
pp. 451-467
Author(s):  
H. KACSER
Keyword(s):  
Calcium Ions ◽  
Sea Urchins ◽  
Critical Role ◽  
Psammechinus Miliaris ◽  
Sea Urchin Egg ◽  
Dark Ground ◽  
Artificial Activation ◽  
Kinetics Of ◽  
Cortical Change

The kinetics of the dark ground cortical change in fertilized sea urchins has been analysed. In normal eggs of Psammechinus miliaris the change appears to obey an autocatalytic mechanism. The evidence from artificial activation suggests that the initiation of the response is caused by a relatively unspecific event. The critical role of calcium is considered in relation to the evidence from eggs fertilized in capillary tubes. This suggests that calcium ions are not concerned with the initiation but with the propagation of the response. The primary change in activation may consist of an increase in permeability at the site of initiation.

scholarly journals Metabolic similarities between fertilization and phagocytosis. Conservation of a peroxidatic mechanism.

1979 ◽  
Vol 149 (4) ◽  
pp. 938-953 ◽  
Author(s):  
S J Klebanoff ◽  
C A Foerder ◽  
E M Eddy ◽  
B M Shapiro
Keyword(s):  
Sea Urchin ◽  
Polymorphonuclear Leukocytes ◽  
Cortical Granules ◽  
Sea Urchin Eggs ◽  
Sea Urchin Egg ◽  
Hatching Process ◽  
Fertilization Membrane ◽  
Catalyzed Reactions ◽  
Kinetics Of ◽  
Estrogen Binding

At the time of fertilization, sea urchin eggs release a peroxidase which, together with H2O2 generated by a respiratory burst, is responsible for hardening of the fertilization membrane. We demonstrate here that the ovoperoxidase of unfertilized eggs is located in cortical granules and, after fertilization, is concentrated in the fertilization membrane. Fertilization of sea urchin eggs or their parthenogenetic activation with the ionophor A23187 also results in (a) the conversion of iodide to a trichloroacetic acid-precipitable form (iodination), (b) the deiodination of eggs exogenously labeled with myeloperoxidase and H2O2, (c) the degradation of thyroxine as measured by the recovery of the released radioiodine at the origin and in the inorganic iodide spot on paper chromatography, and (d) the conversion of estradiol to an alcohol-precipitable form (estrogen binding). The iodination reaction and the binding of estradio occurs predominantly in the fertilization membrane where the ovoperoxidase is concentrated. From the estimation of the kinetics of incorporation of iodine, we determine that the peroxidative system is active for 30 min after fertilization, long after hardening of the fertilization membrane is complete. Most of the bound iodine is lost during the hatching process. Iodination of albumin is catalyzed by the material released from the egg during fertilization, when combined with H2O2 and iodide. Iodination, thyroxine degradation, and estradiol binding are inhibited by azide, cyanide, aminotriazole, methimazole, ascorbic acid and ergothioneine, all of which can inhibit peroxidase-catalyzed reactions. These responses of the sea urchin egg to fertilization are strikingly similar to the changes induced in polymorphonuclear leukocytes by phagocytosis and, in both instances, a peroxidative mechanism may be involved.

Fertilization Membrane Structure as Revealed by Freeze Etching

1968 ◽  
Vol 26 ◽  
pp. 136-137
Author(s):  
Walter J. Humphreys ◽  
G. Oscar Kreutziger
Keyword(s):  
Membrane Structure ◽  
Membrane Surface ◽  
Strongylocentrotus Purpuratus ◽  
Vitelline Membrane ◽  
Cortical Granules ◽  
Fracture Planes ◽  
Inner Surface ◽  
Surface Replica ◽  
Fertilization Membrane ◽  
Freeze Etching

Many evenly spaced papillae on the surface of the unfertilized egg of Strongylocentrotus purpuratus are revealed with great clarity by freeze etching. They measure about 0.25 μ in diameter and 0.5 μ in length. When flat fracture planes through the cortical granules are obtained, differential etching causes the internal components to appear similar to the structures seen in sectioned eggs. The folded laminar component stands out with a distinctive texture. At fertilization, basic structural subunits 40-45 A° in diameter, originating from ruptured cortical granules, become organized on the inner surface of the vitelline membrane to form an array of closely packed, parallel, 197 A° wide strands diagonally striated by regularly repeating units 108 A° apart at an angle of about 72° to the long axes of the strands.Figure 1 is a surface replica of the fertilization membrane as it appears 90 seconds after fertilization. As in the replicas of isolated and dried fertilization membranes made by Inoue et al. the strands extend into the somewhat regularly spaced shallow protrusions on the membrane surface.

Fertilization Membranes and Sea Urchin Embryos Studied by Scanning Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 530-531
Author(s):  
Walter J. Humphreys ◽  
David T. Lindsay
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Sea Urchin ◽  
Structural Features ◽  
Vitelline Membrane ◽  
Cortical Granules ◽  
Freeze Dried ◽  
Fertilization Membrane ◽  
Ultrathin Sections ◽  
Scanning Electron

Scanning electron microscopy (SEM) of specimens freeze-dried after fixation in Parducz fixative and ultrathin sections of the sea urchin, Strongylocentrotus purpuratus show that the egg is covered by many papillae about 0.25μ in diameter and 0.5μ long (Fig. 1a). When the vitelline layer lifts away from the surface of the egg at the time of fertilization it has many uniformly spaced protrusions that persist as prominent and consistent structural features of the fertilization membrane, which forms when material from ruptured cortical granules is added to the inner surface of the raised vitelline membrane. Dimensions of the protrusions, their spacing on the membrane, and their projection in a direction outward from the egg (Fig. 1b) suggests that they originate when the vitelline layer lifts away from the egg surface in the form of a somewhat distorted and expanded replica of the papillae-bearing surface of the unfertilized egg.

scholarly journals IMMUNO-ELECTRON MICROSCOPE ANALYSIS OF THE SURFACE LAYERS OF THE UNFERTILISED SEA URCHIN EGG

1964 ◽  
Vol 23 (3) ◽  
pp. 629-650 ◽  
Author(s):  
Jane Baxandall ◽  
P. Perlmann ◽  
B. A. Afzelius
Keyword(s):  
Structural Changes ◽  
Paracentrotus Lividus ◽  
Vitelline Membrane ◽  
Antigenic Determinants ◽  
Cortical Granules ◽  
Surface Layers ◽  
Antibody Treatment ◽  
Heat Stable ◽  
Antigenic Sites ◽  
Sea Urchin Egg

The immunological properties of the surface layers of Paracentrotus lividus eggs have been studied further by using ferritin-labelled antibody to localise specific antigenic sites. In order to detect a wider spectrum of antigenic determinants, several antisera against egg and jelly substance have been employed in combination with absorption procedures using lyophilised antigen. This use of absorbed antisera was made feasible by adding ferritin label in a second antiserum layer of ferritin-anti-γ-globulin. Eggs were treated with antibody for short periods to detect antigenic sites without incurring structural changes (shown in previous paper) resulting from long antibody treatment. Unspecific ferritin uptake, found in pinocytotic vesicles and yolk granules, is considered in relation to yolk formation. The jelly layer, found to be immunologically heterogeneous, included one component interacting with antijelly γ-globulin and one with antiegg γ-globulin. The vitelline membrane proved to be rich in egg antigens (heat-stable and heat-labile). The role of this layer in specificity of fertilisation, parthenogenetic activation, and the possibility of being analogous to a basement membrane are discussed. Few antigenic sites were found on the plasma membrane with antiegg γ-globulin. This γ-globulin resulted in some specific labelling of cortical granules and its action is considered in relation to the permeability properties of the egg.

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