scholarly journals A CYTOLOGICAL STUDY OF ARTIFICIAL PARTHENOGENESIS IN THE SEA URCHIN ARBACIA PUNCTULATA

1970 ◽  
Vol 47 (1) ◽  
pp. 140-158 ◽  
Author(s):  
Martin I. Sachs ◽  
Everett Anderson
Keyword(s):  
Endoplasmic Reticulum ◽  
Sea Urchin ◽  
Nuclear Division ◽  
Annulate Lamellae ◽  
Cortical Granules ◽  
Smooth Variety ◽  
Mitotic Apparatus ◽  
Arbacia Punctulata ◽  
The Matrix ◽  
Cell Embryo

Eggs of the sea urchin Arbacia punctulata were artificially activated with hypertonic seawater. The artificially activated eggs undergo the cortical reaction which is not distinguished by a wavelike progression as in the case of inseminated eggs. The cortical granules are released at random loci at the surface of the egg and result in spaces separated by large cytoplasmic projections. Unreacted cortical granules and ribosomes are found within the matrix comprising the large cytoplasmic projections. No "fertilization cone" is formed. The subsequent release of additional cortical granules results in the formation of a continuous perivitelline space, 15 min following activation. 85 min postactivation, an organization of annulate lamellae, endoplasmic reticulum of the smooth variety, and microtubules around a centriole is observed prior to nuclear division. Before the breakdown of the nuclear envelope a streak stage is formed. The streak is composed of a central core of annulate lamellae and is encompassed by endoplasmic reticulum and vesicular components. Condensation of chromatin is followed by the establishment of the mitotic apparatus. Centrioles were not found in the mature egg; however, they are present after activation prior to the first nuclear division, in the four-cell embryo, multicellular embryo, and at blastula. Artificially activated eggs have been observed to develop to the pluteus stage in more than 50% of the eggs treated.

scholarly journals Electron Microscopy of the Centrifuged Sea Urchin Egg, with a Note on the Structure of the Ground Cytoplasm

1960 ◽  
Vol 7 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Paul R. Gross ◽  
Delbert E. Philpott ◽  
Sylvan Nass
Keyword(s):  
Sea Urchin ◽  
Composite Structures ◽  
Annulate Lamellae ◽  
Cortical Granules ◽  
Clear Zone ◽  
Arbacia Punctulata ◽  
Large Numbers ◽  
Sea Urchin Egg ◽  
Size Number

Centrifuged, unfertilized eggs of the sea urchin, Arbacia punctulata, have been studied with the electron microscope. Subcellular particles were stratified by centrifuging living cells, known to be normally fertilizable, for five minutes at 3,000 g. The layered subcellular particles, including cortical granules, 16 mµ RNP particles, pigment, yolk, mitochondria, and oil droplets, possess characteristic ultrastructural features by which they may be identified in situ. The clear zone contains 16 mµ particles, most of them freely dispersed, scattered mitochondria, and a few composite structures made up of annulate lamellae in parallel layers or in association with dense, spherical aggregates of the RNP particles. Free 16 mµ particles are found, in addition, throughout the cell, in the interstices between the stratified larger particles. They show a tendency to form ramifying aggregates resulting from certain types of injury to the cell. A few vesicular structures, found mainly in the clear zone, have attached RNP particles, and appear to be related to the ER of tissue cells. Other vesicles, bounded by smooth membranes, are found throughout the cell. These are extremely variable in size, number, and distribution; their total number appears to depend upon conditions of fixation. It is suggested that limited formation of such structures is a normal property of the ground cytoplasm in this cell, but that fixed cells with very large numbers of smooth surfaced vesicles have produced the latter as a response to chemical injury. A model of the ground cytoplasm is proposed whose aim is to reconcile the rheological behavior of the living cell with the ultrastructural features observed.

scholarly journals OOCYTE DIFFERENTIATION IN THE SEA URCHIN, ARBACIA PUNCTULATA, WITH PARTICULAR REFERENCE TO THE ORIGIN OF CORTICAL GRANULES AND THEIR PARTICIPATION IN THE CORTICAL REACTION

1968 ◽  
Vol 37 (2) ◽  
pp. 514-539 ◽  
Author(s):  
Everett Anderson
Keyword(s):  
Sea Urchin ◽  
Golgi Complex ◽  
Morphological Evidence ◽  
Cortical Granule ◽  
Perivitelline Space ◽  
Unit Membrane ◽  
Cortical Granules ◽  
Arbacia Punctulata ◽  
Cortical Reaction ◽  
Oocyte Differentiation

This paper presents morphological evidence on the origin of cortical granules in the oocytes of Arbacia punctulata and other echinoderms. During oocyte differentiation, those Golgi complexes associated with the production of cortical granules are composed of numerous saccules with companion vesicles. Each element of the Golgi complex contains a rather dense homogeneous substance. The vesicular component of the Golgi complex is thought to be derived from the saccular member by a pinching-off process. The pinched-off vesicles are viewed as containers of the precursor(s) of the cortical granules. In time, they coalesce and form a mature cortical granule whose content is bounded by a unit membrane. Thus, it is asserted that the Golgi complex is involved in both the synthesis and concentration of precursors utilized in the construction of the cortical granule. Immediately after the egg is activated by the sperm the primary envelope becomes detached from the oolemma, thereby forming what we have called the activation calyx (see Discussion). Subsequent to the elaboration of the activation calyx, the contents of cortical granules are released (cortical reaction) into the perivitelline space. The discharge of the constituents of a cortical granule is accomplished by the union of its encompassing unit membrane, in several places, with the oolemma.

Non-plasmalemmal localisation of the major ganglioside in sea urchin eggs

Zygote ◽  
1993 ◽  
Vol 1 (3) ◽  
pp. 215-223 ◽  
Author(s):  
Hidehiko Shogomori ◽  
Kazuyoshi Chiba ◽  
Hideo Kubo ◽  
Motonori Hoshi
Keyword(s):  
Endoplasmic Reticulum ◽  
Sea Urchin ◽  
Indirect Immunofluorescence ◽  
Immunofluorescence Microscopy ◽  
Mitotic Apparatus ◽  
Sea Urchin Eggs ◽  
Indirect Immunofluorescence Microscopy ◽  
The One ◽  
Major Ganglioside ◽  
Hemicentrotus Pulcherrimus

SummaryM5 ganglioside (NeuGcα2–6Glcβl-' Cer) is the predominant glycosphingolipid in sea urchin eggs. Distribution of M5 ganglioside was studied in unfertilised and fertilised eggs of the sea urchin Hemicentrotus pulcherrimus by indirect immunofluorescence microscopy. In the cortices of unfertilised eggs, anti-M5 antibody strongly stained the submembranous, polygonal and tubular network of endoplasmic reticulum that was revealed by a membrane-staining dye, DiIC18(3). In addition to the cortical network of endoplasmic reticulum, at least two morphologically distinct vesicles were positive to the antibody. In the cortices isolated from fertilised eggs 30 min after insemination, the antibody stained only a similar network of endoplasmic reticulum, presumably the one reconstructed 5–10 min after fertilisation. During mitosis the endoplasmic reticulum is known to aggregate within the asters of the mitotic apparatus. Indeed, the antibody stained the asters and (more strongly) the vesicular components attaching to the periphery of the mitotic apparatus.

Ultrastructural changes in nuclear membranes and organelle associations during mitosis of the aquatic fungus Entophlyctis sp.

1975 ◽  
Vol 53 (7) ◽  
pp. 627-646 ◽  
Author(s):  
Martha J. Powell
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Nuclear Division ◽  
Ultrastructural Changes ◽  
Aquatic Fungus ◽  
Electron Microscopic ◽  
Mitotic Apparatus ◽  
Inner Membrane ◽  
Nuclear Membranes ◽  
Spindle Microtubules

Electron microscopic observations on an endobiotic chytrid, Entophlyctis sp., have revealed a mitotic apparatus which is presently unique among fungi. Daughter nuclear envelopes are reconstituted from cisternae apparently proliferated by the inner membrane of the nuclear envelope. Before nuclear division, centrioles replicate and migrate to the poles of the nucleus. Large pores appear at this time in a depression of the nuclear envelope opposite the paired centrioles. This region of the envelope fragments and leaves polar fenestrae as spindle microtubules appear in the nucleus. The inner membrane of the nuclear envelope then invaginates and proliferates cisternae until a layer of inner membrane cisternae lines the original nuclear envelope at late metaphase. Connections between the inner membrane of the original nuclear envelope and the cisternae persist until telophase. As the spindle elongates and the inner membrane cisternae fuse centripetally to form a reticulum around the chromatin mass, the original nuclear envelope opens more at the poles. The reticulum becomes the nuclear envelope of the new daughter nuclei. When the original envelope finally disperses, it is distinguishable from the endoplasmic reticulum only by the presence of pores. Microbodies are consistently associated with the original nuclear envelope and appear adjacent to the new daughter envelopes at the end of telophase. Densely staining arms project from the sides of the primary centrioles toward the polar mitochondria.

scholarly journals Source and sinks for the calcium released during fertilization of single sea urchin eggs.

1985 ◽  
Vol 100 (5) ◽  
pp. 1522-1527 ◽  
Author(s):  
A Eisen ◽  
G T Reynolds
Keyword(s):  
Endoplasmic Reticulum ◽  
Intracellular Calcium ◽  
Sea Urchin ◽  
Image Intensifier ◽  
Metabolic Activation ◽  
Calcium Transient ◽  
Clear Zone ◽  
Calcium Store ◽  
Arbacia Punctulata ◽  
Mitochondrial Uncouplers

The source and sinks for the intracellular calcium released during fertilization were examined in single eggs from the sea urchin, Arbacia punctulata. Single eggs were microinjected with the calcium photoprotein, aequorin. The calcium-aequorin luminescence was measured with a microscope-photomultiplier or observed with a microscope-image intensifier-video system. In the normal egg a propagated release has been observed. The source of the calcium was investigated in the organelle-stratified centrifuged egg and by the use of mitochondrial uncouplers. In the organelle-stratified centrifuged egg, the calcium-aequorin luminescence was found to originate from the clear zone. The principal constituent of the clear zone is the endoplasmic reticulum. Other potential sources of calcium are the mitochondria. Their contribution to the calcium transient was investigated by exposure of aequorin-injected eggs to mitochondrial uncouplers either before or after fertilization. There was no calcium released from the mitochondria before fertilization. A very large calcium store was released from the mitochondria after fertilization. Interestingly, eggs fertilized in the presence of uncouplers showed no increase in the calcium-aequorin luminescence over untreated eggs. Apparently, in the absence of mitochondrial uptake, other sinks for calcium with affinity and capacity similar to the mitochondria exist, but their nature is unknown. We suggest that the endoplasmic reticulum is the source of the intracellular calcium released upon fertilization and that the mitochondria are the principal sink. The results are discussed with regard to the metabolic activation of the egg.

Ultrastructural changes during nuclear maturation in Bufo arenarum oocytes

Zygote ◽  
1999 ◽  
Vol 7 (3) ◽  
pp. 261-269 ◽  
Author(s):  
Inés Ramos ◽  
Beatriz C. Winik ◽  
Susana Cisint ◽  
Claudia Crespo ◽  
Marcela Medina ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Ultrastructural Changes ◽  
Oocyte Nucleus ◽  
Annulate Lamellae ◽  
Perivitelline Space ◽  
Cortical Granules ◽  
Animal Pole ◽  
Nuclear Maturation ◽  
Bufo Arenarum ◽  
Freely Suspended

During progesterone-induced nuclear maturation the oocytes of Bufo arenarum undergo a series of nuclear and cytoplasmic changes. The breakdown of heterocellular communications between the follicular cell projections and the oocyte microvilli, and the consequent enlargement of the perivitelline space, were observed at the animal pole. The more evident cytoplasmic feature during nuclear maturation comprised the gathering of glycogen granules in clusters, some phagocytosed by empty vesicles. With respect to the location of these vesicles, some were observed in close proximity to the oolemma and others were freely suspended in the perivitelline space, extruded from the oocyte. Other visible events were the disruption of the annulate lamellae, the formation of an elaborate cortical endoplasmic reticulum and the rearrangement of the cortical granules in a monolayer immediately beneath the oolemma together with aggregates of endoplasmic reticulum cisternae. Our results show that during nuclear maturation the nuclear oocyte changes include a flattening of the spherical oocyte nucleus, its migration towards the surface of the animal pole, the disappearance of the nucleoli and the dissolution of the nuclear envelope.

scholarly journals The Effect of Partial Protein Extraction on the Structure of the Eggs of the Sea Urchin, Arbacia punctulata

1960 ◽  
Vol 7 (1) ◽  
pp. 21-26 ◽  
Author(s):  
R. E. Kane
Keyword(s):  
Nuclear Envelope ◽  
Sea Urchin ◽  
Protein Extraction ◽  
Extraction Procedure ◽  
Cellular Protein ◽  
Soluble Proteins ◽  
Annulate Lamellae ◽  
Cytoplasmic Matrix ◽  
Arbacia Punctulata ◽  
Cell Structures

The structure of the eggs of the sea urchin, Arbacia punctulata, has been investigated after the removal of one-half of the cellular protein. The procedure involves treatment of the eggs with 30 per cent ethanol at -10°C. followed by extraction of the soluble proteins with water. The eggs remain intact, although all of the cytoplasmic matrix is removed. Most cell structures can still be identified, although only the membranes of most remain. The mitochondria lose all of their matrix but retain the inner membranes or cristae. The annulate lamellae appear unaffected by this extraction procedure, remaining intact and apparently undamaged. The nuclear envelope is also retained, although it often undergoes a curious disorganization, apparently as the result of the separation of its two layers. The significance of these observations with respect to the structure of the envelope is discussed.

Ultrastructural localization of calcium in unfertilized sea-urchin eggs

1978 ◽  
Vol 31 (1) ◽  
pp. 101-115
Author(s):  
C.A. Cardasis ◽  
H. Schuel ◽  
L. Herman
Keyword(s):  
Sea Urchin ◽  
Calcium Binding ◽  
Pigment Granule ◽  
Ultrastructural Localization ◽  
Cortical Granules ◽  
Arbacia Punctulata ◽  
Sea Urchin Eggs ◽  
Initial Fixation ◽  
Stimulus Secretion Coupling ◽  
Matrix Substance

The pyroantimonate technique was employed to identify the binding sites for calcium in unfertilized Arbacia punctulata and Strongylocentrotus purpuratus eggs. Since antimony is non-specific and binds with a variety of cations, the indentification of calcium was established by specific chelation with ethyleneglycol tetra-acetic acid (EGTA) and X-ray microprobe analysis. Antimony deposits were observed on the egg's membranes, i.e. plasma, cortical (secretory) granule, pigment granule, smooth-surfaced vesicle, and yolk platelet. Deposits were also observed in the mitochondria, rod-containing vesicles, and the vitelline layer. Two types of yolk platelets were observed: a more numerous electron-opaque platelet which had precipitate along its limiting membrane as well as within the stored-matrix substance, and a less-frequently seen platelet with lower electron opacity which contained precipitate only along its limiting membrane. Deposits were reduced at all sites following exposure of eggs to EGTA either prior to or after osmium-antimonate fixation. Initial fixation in glutaraldehyde followed by postfixation in osmium-antimonate solutions provided better preservation of structure but less precipitation than direct fixation in osmium-antimonate. The organelle sites of calcium binding identified within unfertilized sea-urchin eggs may participate in stimulus-secretion coupling (exocytosis of the cortical granules) and the activation of embryogenesis at fertilization.

scholarly journals A CYTOLOGICAL STUDY OF THE RELATION OF THE CORTICAL REACTION TO SUBSEQUENT EVENTS OF FERTILIZATION IN URETHANE-TREATED EGGS OF THE SEA URCHIN, ARBACIA PUNCTULATA

1970 ◽  
Vol 47 (3) ◽  
pp. 646-665 ◽  
Author(s):  
Frank J. Longo ◽  
Everett Anderson
Keyword(s):  
Sea Urchin ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Cell Stage ◽  
Zygote Nucleus ◽  
Arbacia Punctulata ◽  
Cortical Reaction ◽  
Female Pronucleus ◽  
Almost All ◽  
Granule Release

Eggs of the sea urchin, Arbacia punctulata, treated with 3% urethane for 30 sec followed by 0.3% urethane and inseminated are polyspermic and fail to undergo a typical cortical reaction. Upon insemination the vitelline layer of urethane-treated eggs either does not separate or is raised only a short distance from the oolemma. 1–6 min after insemination, almost all of the cortical granules remain intact and are dislodged from the plasmalemma. Later (6 min to the two-cell stage) some cortical granules are released randomly along the surface of the zygote. Not all zygotes show the same degree of cortical granule dehiscence; most of them experience little if any granule release whereas others demonstrate considerably more. The thickness of the hyaline layer appears to be directly related to the number of cortical granules released. Subsequent to pronuclear migration, several male pronuclei become associated with the female pronucleus. Later the male and female pronuclear envelopes contact and the outer and the inner laminae fuse, thereby forming the zygote nucleus. The male pronuclei remaining in the cytoplasm increase in size and progressively migrate to, and fuse with, the zygote nucleus. By 60 min some zygotes appear to contain only one large zygote nucleus which subsequently enters mitosis. Other zygotes possess a number of male pronuclei which remain unfused, and later these pronuclei along with the zygote nucleus undergo mitosis. There does not appear to be a direct relation between the number of cortical granules a zygote possesses and the above mentioned dichotomy.

An Estimate of the Amount of Microtubule Protein in the Isolated Mitotic Apparatus

1970 ◽  
Vol 6 (1) ◽  
pp. 159-176
Author(s):  
W. D. COHEN ◽  
L. I. REBHUN
Keyword(s):  
Electron Microscopy ◽  
Sea Urchin ◽  
Cross Sections ◽  
Mitotic Apparatus ◽  
Arbacia Punctulata ◽  
Molecular Weights ◽  
Cellular Factors ◽  
Microtubule Protein ◽  
Specific Orientation ◽  
Existing Data

The microtubule content of the isolated mitotic apparatus of sea-urchin eggs (Arbacia punctulata has been investigated by electron microscopy. Cross-sections were made through asters or spindles of flat-embedded mitotic apparatuses of known mitotic stage and specific orientation in the block. Cross-sections between chromosomes and poles of five metaphase half-spindles revealed approximately 2000-2300 sectioned microtubules. The number was somewhat higher in three anaphase half-spindles examined, approximately 2400-2600. A method was devised for calculating the total number of microtubules in an aster, based upon the number of microtubules appearing in cross-sections. Application of this method to selected mitotic apparatuses enabled calculation of the total number of microtubules in metaphase mitotic apparatuses of average dimensions. Using a 13-protofilament model of the microtubule and existing data on possible monomer sizes and molecular weights, the total amount of microtubule protein in the isolated mitotic apparatus was calculated. The values obtained are in the range of about 1-2 x 10-8 mg microtubule protein per isolated mitotic apparatus. These values are close to those reported for the 4-5s protein of the isolated mitotic apparatus, but are considerably lower than the amount of 22s protein. The results are discussed with respect to cellular factors which determine microtubule number, and the possible sources and origin of mitotic microtubule protein.

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