Intranuclear Lipids in the Early Oocytes of Heteropneustes Fossilis (Teleostei)

1963 ◽  
Vol s3-104 (65) ◽  
pp. 69-73
Author(s):  
B. R. SESHACHAR ◽  
R. P. NAYYAR
Keyword(s):  
Nuclear Membrane ◽  
Lipid Bodies ◽  
Heteropneustes Fossilis ◽  
Yolk Formation

Purely lipid bodies have been encountered inside the nucleus of early oocytes of Heteropneustes fossilis. These are mixtures of phospholipids and triglycerides. They occur independently of the nucleoli. With the growth of oocyte they increase in size and number and move towards the nuclear membrane. During later stages they diffuse out into the cytoplasm presumably to take part in yolk formation.

Memoirs: On the Relation of the Mitochondria and Golgi Apparatus to Yolk-Formation in the Egg-Cells of the Common Earthworm, Lumbricus Terrestris

1925 ◽  
Vol s2-69 (274) ◽  
pp. 291-316
Author(s):  
LESLIE A. HARVEY
Keyword(s):  
Golgi Apparatus ◽  
Nuclear Membrane ◽  
Lumbricus Terrestris ◽  
Yolk Formation ◽  
Central Mass ◽  
The Common ◽  
Yolk Nucleus ◽  
Earthworm Lumbricus

1. The yolk-nucleus is merely a mass of mitochondria. 2. The mitochondria arise as a cap of threads over the nucleus, and this cap grows in size and density, migrates away from the nuclear membrane and breaks up into its component mitochondrial threads. These threads become evenly spread throughout the cytoplasm of the cell. 3. The mitochondria are not clearly defined in the very young oogonia. 4. The Golgi apparatus consists of numbers of Golgi elements lying separate in the cytoplasm. There is never any attempt at concentration of these elements round one central mass. 5. The Golgi elements are probably little platelets or spheroids somewhat resembling blood corpuscles in shape. They are not rods. As fixed by Da Fano technique, each element is a little plate with a very lightly impregnating centre and a very heavily impregnating rim. 6. The Golgi elements may probably arise from the cytoplasm. 7. The nucleus contains two nucleoli; an early arising karyosome, homogeneous and solid in structure, and a plasmo some arising later This plasmosome is liquid in consistency and contains an argentophil core. The karyosome disappears before the oocyte is half grown, but the plasmosome remains in the nucleus while the egg remains in the ovary. 8. No visible nucleolar extrusions into the cytoplasm were observed. 9. Yolk probably arises from the cytoplasm; no direct metamorphosis of either mitochondria, Golgi apparatus, or nucleolus into yolk was observed.

scholarly journals Memoirs: Studies in the Origin of Yolk. VI. The Crustacean Cogenesis

1931 ◽  
Vol s2-74 (296) ◽  
pp. 669-700
Author(s):  
DES RAJ BHATIA ◽  
VISHWA NATH
Keyword(s):  
Nuclear Membrane ◽  
Neutral Red ◽  
Sensu Stricto ◽  
Yolk Granule ◽  
Yolk Formation ◽  
Rana Tigrina ◽  
Nuclear Ring ◽  
First Time ◽  
Vacuolar System ◽  
Peripheral Regions

Palaemon lamarrei 1. In the oogonia there are no granules which can be assigned to the category of mitochondria. They appear for the first time in young oocytes in the form of a juxta-nuclear heap of granules or in the form of a horseshoe closely embracing the nuclear membrane. Soon they arrange themselves in the form of a circum-nuclear ring which gradually expands towards the periphery of the oocyte without breaking away from the nuclear membrane. At the same time the marginal mitochondria of the ring grow in size till ultimately they give rise to albuminous yolk, which therefore appears for the first time in the peripheral regions of the cytoplasm (cf. Oniscus, King, 1926, and Rana tigrina, Nath, 1931). 2. A yolk-forming mitochondrium first swells up; but it is still poorly fixed and stained with Bouin-haematoxylin, like the unchanged mitochondria. The process of growth continues and the swelling mitochondria now show an internal differentiation in the form of minute granules or very small vacuoles. Such mitochondria are only slightly better fixed and stained with Bouin-haematoxylin. Gradually they are completely shorn of their lipoidal constituents, condensing at the same time more and more of protein material. Ultimately they give rise to albuminous yolk, sensu stricto, which is fixed and stained excellently in Bouin-haematoxylin. 3. In the earliest oocytes the nucleolus throws out into the cytoplasm deeply basophil pieces which are more or less uniformly dispersed. Soon they disappear. Hereafter the nucleolar extrusions are very minute, but they remain restricted to the perinuclear region. They never wander into the general cytoplasm or at least into its peripheral regions where protein yolk appears for the first time. A direct origin of the yolk granule from the extrusion must, therefore, be ruled out. But the possibility of the extrusions going into solution and thus indirectly contributing towards yolk cannot be eliminated. 4. Although the mitochondria can be easily observed in the fresh cover-slip preparations of young oocytes, the Golgi elements cannot be demonstrated unless the material is osmicated for at least twenty-two hours. Chemically the Golgi elements are lipoidal (fat-like). They are not stainable with neutral red. 5. In the oogonia and the earliest oocytes the Golgi elements exist in the form of vesicles, each vesicle showing a thick osmiophilic cortex and a central osmiophobic area. 6. During oogenesis many vesicles grow enormously in size, store up neutral fats inside them, and give rise to the fatty yolk as in Lithobius, spider, Otostigmus, Luciola, cockroach, Dysdercus, and Ophiocephalus (Nath, and Nath and collaborators), in Oniscus (King), in saw-flies (Gresson), and in Helix (Brambell). 7. The vacuolar system is absent in the prawn and also in the crab. Paratalphusa spinigera. 8. The Golgi elements of the crab behave exactly like those of the prawn, but the mitochondria, on the other hand, remain inactive and have no visible relationship with yolk formation. 9. In the crab also there are well-marked nucleolar extrusions. As in the prawn a prominent circum-nuclear ring of these granules is established early in oogenesis. But, unlike the prawn, granules from this ring continue to wander into the cytoplasm at the periphery of which they directly grow into the albuminous yolk.

scholarly journals Memoirs: Yolk-Formation in Periplaneta Orientalis

1931 ◽  
Vol s2-74 (294) ◽  
pp. 257-274
Author(s):  
R.A. R. GRESSON
Keyword(s):  
Epithelial Cells ◽  
Nuclear Membrane ◽  
Neutral Red ◽  
Follicle Cells ◽  
Osmic Acid ◽  
Staining Reaction ◽  
Yolk Formation ◽  
Cover Slip ◽  
Pass Through ◽  
The Masses

1. The Golgi vacuoles and fatty yolk-formation in Peri-planeta orientalis were studied by means of Mann-Kopsch, Kolatschev, 2 per cent, osmic acid and neutral red preparations. 2. The Golgi vacuoles of the young oocytes are situated in the vicinity of the nucleus; later they pass to the periphery of the cell. In the older oocytes, towards the posterior end of the ovarioles, they become evenly distributed in the ooplasm, store up fat, increase greatly in size, and give rise to the fatty yolkspheres. In the older oocytes they darken much more rapidly in 2 per cent, osmic acid. 3. In neutral red preparations clear non-stained vacuoles are seen to occupy similar positions to those of the dark bodies of the osmic preparations; on introducing a few drops of 2 per cent, osmic acid under the cover slip the vacuoles develop an osmophilic rim. These Golgi vacuoles are not stained by neutral red. 4. In 2 per cent, osmic acid preparations the Golgi vacuoles are seen to consist of an osmophilic rim and a central clear substance. 5. The Golgi vacuoles of the follicle-cells are similar to those of the egg, except that they do not increase greatly in size and are not so rapidly darkened in 2 per cent, osmic acid. 6. The nucleoli of the early oocytes are spherical in shape and are amphiphil or slightly basophil in staining reaction; they may contain small vacuoles. In slightly older oocytes the nucleoli are non-vacuolated; they become strongly basophil, irregular in outline, and, at the same time, give rise to emissions which pass through the nuclear membrane to the ooplasm, where they ultimately disappear. In a certain few oocytes the nucleolus was seen to have broken up into several masses, some of the latter, in all probability, fragmenting to form nucleolar extrusions. In a certain oocyte one of the masses was observed to be vacuolated before the first type of extrusion had ceased. 7. In the more highly developed oocytes the first type of nucleolar emission ceases, and the nucleolus becomes more spherical in outline. Numerous vacuoles appear which give origin to nucleolar extrusions. The latter become vacuolated, either before extrusion through the nuclear membrane, or later in the ooplasm. 8. The second type of nucleolar extrusions pass to the periphery of the egg. Later they become evenly distributed in the ooplasm, where they fragment to forin homogeneous granules. The latter form clear spheres (Kolatschev material) which rapidly increase in size to form the albuminous yolk-globules. 9. Chromatin was not observed in the oocyte nuclei, nucleoli, or nucleolar extrusions (Feulgen's technique). The chromatin of the follicle-cells is in the form of granules connected by threads (which give the chromatin reaction). The chromatin of the follicular epithelial-cells was observed as granules scattered through the nuclei. 10. Bacteroid forms were observed in the ooplasm at the periphery of the older oocytes. 11. The method of yolk-formation is similar to that of Peri-planeta americanaas described by Nath and Piare Mohan. 12. The writer's conclusions regarding the shape and character of the Golgi vacuoles agree with tne findings of Nath and his co-workers and with the former conclusions of the present writer for oocyte Golgi vacuoles.

Memoirs: Note on the Oogenesis of Peripatopsis Capensis (Purcell)

1926 ◽  
Vol s2-70 (279) ◽  
pp. 553-558
Author(s):  
SEANA D. KING
Keyword(s):  
Nuclear Membrane ◽  
Yolk Formation ◽  
Small Grains

1. Nucleolar budding takes place actively in the very young oocytes, and more slowly later ; the particles budded off pass out towards the nuclear membrane, but have not been actually traced into the cytoplasm. 2. The mitochondria are filamentous in younger oocytes ; they lie at first in a loose cloud near the nucleus, then pass out through the cytoplasm, fragmenting to small grains which are evenly distributed. 3. Yolk-formation begins before the mitochondria become distributed. The yolk is fatty and is formed in groups, but its source has not been determined.

Memoirs: Nucleolar Phenomena During Oogenesis in Certain Tenthredinidae

1929 ◽  
Vol s2-73 (290) ◽  
pp. 177-196
Author(s):  
R.A. R. GRESSON
Keyword(s):  
Nuclear Membrane ◽  
Close Contact ◽  
Outer Part ◽  
The Other ◽  
Yolk Formation ◽  
Small Bodies ◽  
Inner Surface ◽  
Similar Body

1. The material has been obtained from parthenogenetic females. In Thrinax macula at least two kinds of females exist, one male-producing, the other female-producing. In Allantus pallipes males have not been found. 2. In the early oocytes of Thrinax macula the nucleoli are basophil; as they increase in size they develop an oxyphil margin. Later, the oxyphil part becomes rounded off and separates from the basophil. The basophil nucleolus now consists of a small basophil body surrounded by a basophil or slightly oxyphil portion. Vacuoles appear in the outer part, and become larger, in some cases containing dark granules which probably originate from the darkly staining body. The granules increase in size and ultimately become liberated as separate bodies, consisting of a basophil part surrounded by more faintly staining material. These buds may also originate from large vacuolated masses given off from the basophil nucleolus. The buds pass towards the periphery, but were not observed in the ooplasm or passing through the nuclear membrane. They apparently disappear after yolk-formation has commenced; the basonucleolus persists but seems to lose its granules. 3. As the basophil buds are being formed the oxyphil nucleolus enters upon a period of activity, numerous oxyphil buds being liberated. In some cases the oxyphil buds originate from a vacuolated mass as large as the oxyphil nucleolus, and which arose, probably by constriction, from the latter. Oxyphil buds were observed to migrate towards the nuclear membrane. 4. In Allantus pallipes the nucleoli of the early oocytes are basophil; later, they stain more faintly and finally become oxyphil. In the fully formed oocyte before yolk-formation the basophil material is only represented by small bodies containing dark granules. These bodies may be present during the later stages of yolk-formation, when in some cases they occur as basophil bodies without any granules. In one instance a similar body was observed outside the nuclear membrane. The oxyphil nucleolus becomes active before yolk-formation commences; it becomes more marked in the later stages and in many cases the nucleolus appeared to be breaking up. The buds occurred in close contact with the inner surface of the nuclear membrane and, later, somewhat similar bodies were observed in the ooplasm; the latter, however, were difficult to differentiate from the smaller yolk-globules. 5. The origin and behaviour of the oxyphil emissions are similar in both species. The oxyphil buds apparently pass into the ooplasm and are utilized during yolk-formation. The basophil buds of Thrinax macula and the basophil bodies of Allantus pallipes originate from the basonucleolus. The occurrence of basophil bodies without granules in older oocytes, and the presence of one body in one case outside the nuclear membrane of an Allantus oocyte suggest that these bodies lose their granules, and are then extruded into the ooplasm, where they play some part in the nourishment of the oocyte.

Zoospore ultrastructure of Olpidium brassicae and Rhizophlyctis rosea

1977 ◽  
Vol 55 (9) ◽  
pp. 1221-1235 ◽  
Author(s):  
D. J. S. Barr ◽  
V. E. Hartmann
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
The Other ◽  
Lipid Bodies ◽  
Varying Thickness ◽  
Olpidium Brassicae

Zoospore cytology of two lettuce strains (from carrot and plantain) and a cabbage strain of Olpidium brassicae (Woronin) Dang, was compared with that of two isolates of Rhizophlyctis rosea (deBary & Woronin) Fischer. Olpidium brassicae zoospores contain four to six mitochondria grouped around the nucleus: microbodies are closely associated with the nucleus and mitochondria and casually associated with lipid bodies in the cytoplasm; ribosomes are scattered in the cytoplasm; a rhizoplast, 0.65 μm long, extends from kinetosome and non-functional centriole to an area near the nuclear membrane and consists of elongated, very fine fibrils crossed by electron-dense layers (striations) of varying thickness and density; the configuration of the layers of the rhizoplast in the lettuce strains differed from the cabbage strain. Rhizophlyctis rosea zoospores contain many (about 21) mitochondria grouped around the nucleus; elongated microbodies are conspicuous on the posterior and lateral sides of the nucleus and extend into the cytoplasm to lipid bodies; ribosomes are concentrated in an area around the nucleus and are partially enclosed by a net-like and folded arrangement of rough endoplasmic reticulum. Rhizoplasts of R. rosea consist of fine fibrils which extend from the kinetosome and non-functional centriole to the nucleus and are crossed by electron-dense layers; in one isolate the rhizoplast is 0.35 μm long and tapers to a point which is connected by fibrils to a flap of the nucleus in a posteriorly located nuclear pocket; in the other isolate it is 1.35 μm long, and expands into a cone-like segment which abuts onto the flattened, posterior face of the nucleus. The significance of the arrangement of organelles, and in particular the rhizoplast, in chytrid biosystematics is discussed.

The Formation, Structure, Distribution and Frequency of Nuclear Pores

1971 ◽  
Vol 29 ◽  
pp. 518-519
Author(s):  
G. G. Maul
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Dynamic Structure ◽  
Nuclear Pore ◽  
Nuclear Pores ◽  
Filter Function ◽  
Etching Technique ◽  
Selective Filter ◽  
Membranous Part

The chromatin of eukaryotic cells is separated from the cytoplasm by a double membrane. One obvious structural specialization of the nuclear membrane is the presence of pores which have been implicated to facilitate the selective nucleocytoplasmic exchange of a variety of large molecules. Thus, the function of nuclear pores has mainly been regarded to be a passive one. Non-membranous diaphragms, radiating fibers, central rings, and other pore-associated structures were thought to play a role in the selective filter function of the nuclear pore complex. Evidence will be presented that suggests that the nuclear pore is a dynamic structure which is non-randomly distributed and can be formed during interphase, and that a close relationship exists between chromatin and the membranous part of the nuclear pore complex.Octagonality of the nuclear pore complex has been confirmed by a variety of techniques. Using the freeze-etching technique, it was possible to show that the membranous part of the pore complex has an eight-sided outline in human melanoma cells in vitro. Fibers which traverse the pore proper at its corners are continuous and indistinguishable from chromatin at the nucleoplasmic side, as seen in conventionally fixed and sectioned material. Chromatin can be seen in octagonal outline if serial sections are analyzed which are parallel but do not include nuclear membranes (Fig. 1). It is concluded that the shape of the pore rim is due to fibrous material traversing the pore, and may not have any functional significance. In many pores one can recognize a central ring with eight fibers radiating to the corners of the pore rim. Such a structural arrangement is also found to connect eight ribosomes at the nuclear membrane.

A High Resolution Cytochemical Study of Nuclear ATPase in Human Spermatozoa

1975 ◽  
Vol 33 ◽  
pp. 594-595
Author(s):  
A. Sosa ◽  
L. Calzada
Keyword(s):  
High Resolution ◽  
Atpase Activity ◽  
Nuclear Membrane ◽  
Human Sperm ◽  
Sperm Nucleus ◽  
Human Spermatozoa ◽  
Cytochemical Study ◽  
Membrane Bound ◽  
Sperm Nuclei ◽  
Interchromatin Space

The dependence of nuclear metabolism on the function of the nuclear membrane is not well understood. Whether or not the function of the nuclear membrane is partial or totally responsible of the repressed template activity of human sperm nucleus has not at present been elucidated. One of the membrane-bound enzymatic activities which is concerned with the mechanisms whereby substances are thought to cross cell membranes is adenosintriphosphatase (ATPase). This prompted its characterization and distribution by high resolution photogrammetry on isolated human sperm nuclei. Isolated human spermatozoa nuclei were obtained as previously described. ATPase activity was demonstrated by the method of Wachstein and Meisel modified by Marchesi and Palade. ATPase activity was identified as dense and irregularly distributed granules confined to the internal leaflet of the nuclear membrane. Within the nucleus the appearance of the reaction product occurs as homogenous and dense precipitates in the interchromatin space.

Lamin B receptor: role on chromatin structure, cellular senescence and possibly aging

2020 ◽  
Vol 477 (14) ◽  
pp. 2715-2720
Author(s):  
Susana Castro-Obregón
Keyword(s):  
Cellular Senescence ◽  
Nuclear Membrane ◽  
Chromatin Structure ◽  
Cholesterol Synthesis ◽  
Reductase Activity ◽  
Chimeric Protein ◽  
Nuclear Lamina ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Lamin B Receptor

The nuclear envelope is composed by an outer nuclear membrane and an inner nuclear membrane, which is underlain by the nuclear lamina that provides the nucleus with mechanical strength for maintaining structure and regulates chromatin organization for modulating gene expression and silencing. A layer of heterochromatin is beneath the nuclear lamina, attached by inner nuclear membrane integral proteins such as Lamin B receptor (LBR). LBR is a chimeric protein, having also a sterol reductase activity with which it contributes to cholesterol synthesis. Lukasova et al. showed that when DNA is damaged by ɣ-radiation in cancer cells, LBR is lost causing chromatin structure changes and promoting cellular senescence. Cellular senescence is characterized by terminal cell cycle arrest and the expression and secretion of various growth factors, cytokines, metalloproteinases, etc., collectively known as senescence-associated secretory phenotype (SASP) that cause chronic inflammation and tumor progression when they persist in the tissue. Therefore, it is fundamental to understand the molecular basis for senescence establishment, maintenance and the regulation of SASP. The work of Lukasova et al. contributed to our understanding of cellular senescence establishment and provided the basis that lead to the further discovery that chromatin changes caused by LBR reduction induce an up-regulated expression of SASP factors. LBR dysfunction has relevance in several diseases and possibly in physiological aging. The potential bifunctional role of LBR on cellular senescence establishment, namely its role in chromatin structure together with its enzymatic activity contributing to cholesterol synthesis, provide a new target to develop potential anti-aging therapies.

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