scholarly journals ELECTRON MICROSCOPE STUDIES ON THE ORIGIN OF ANNULATE LAMELLAE IN OOCYTES OF NECTURUS

1963 ◽  
Vol 19 (2) ◽  
pp. 391-414 ◽  
Author(s):  
Richard G. Kessel
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Outer Layer ◽  
Annulate Lamellae ◽  
A Chain ◽  
The Individual ◽  
Long Chains

Developing oocytes, ranging from approximately 0.1 to 1.0 mm in diameter, in Necturus were studied with the electron microscope. The outer layer of the nuclear envelope is actively engaged in the formation of vesicular elements along most of its surface, especially in smaller oocytes. Groups of vesicles appear to be released into the ooplasm at about the same time, resulting in long chains of individual vesicles immediately adjacent to the nuclear membrane. This process is repeated so that chains of vesicles grouped in rather ordered ranks extend progressively into the surrounding cytoplasm. Eventually, the cytoplasm becomes more concentrated with chains of vesicles and the distance between the individual rows becomes less. Very soon after a chain of vesicles has been budded off from the nuclear membrane, fine intervesicular connections appear between certain of the vesicles comprising the rows. Several of the vesicles in a row may then fuse, forming short, flattened cisternae. Fusion of vesicles continues, individual rows of vesicles become more closely packed and, finally, regions appear in the cytoplasm which have the appearance of annulate lamellae. Further growth of the lamellae appears to occur by the progressive fusion of vesicles at the ends of those lamellae already present, as well as by the addition of other fusing rows of vesicles.

scholarly journals INTRANUCLEAR AND CYTOPLASMIC ANNULATE LAMELLAE IN TUNICATE OOCYTES

1965 ◽  
Vol 24 (3) ◽  
pp. 471-487 ◽  
Author(s):  
R. G. Kessel
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Outer Layer ◽  
Growth And Development ◽  
Granular Endoplasmic Reticulum ◽  
Fusion Process ◽  
Morphological Evidence ◽  
Annulate Lamellae ◽  
Stages Of Growth

Electron microscope studies were made on various tunicate oocytes at different stages of growth and development. Both the inner and outer lamellae of the perforated nuclear envelope demonstrate considerable blebbing activity. The blebs of the inner lamella detach into the nucleoplasm where they undergo a special type of fusion process resulting in the formation of numerous, usually single, differentiated annulate lamellae of various lengths. The blebbing of the outer layer of the nuclear envelope contributes to the vesicular and granular endoplasmic reticulum characteristically present in the ooplasm and perhaps to the differentiation of cytoplasmic annulate lamellae as well. Cytoplasmic stacks of annulate lamellae frequently have ribosomes associated with them. In addition, granular accumulations are sometimes observed around or between the annuli. The morphological evidence suggests that, at least in many cases, the annuli in the annulate lamellae are patent.

scholarly journals ELECTRON MICROSCOPY OF THE NUCLEAR MEMBRANE OF AMOEBA PROTEUS

1956 ◽  
Vol 2 (4) ◽  
pp. 445-448 ◽  
Author(s):  
Marie H. Greider ◽  
Wencel J. Kostir ◽  
Walter J. Frajola
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Nuclear Membrane ◽  
Outer Layer ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Cell Types ◽  
Amoeba Proteus ◽  
Nuclear Membranes ◽  
Thin Sectioning

An electron microscope study of the nuclear membrane of Amoeba proteus by thin sectioning techniques has revealed an ultrastructure in the outer layer of the membrane that is homologous to the pores and annuli observed in the nuclear membranes of many other cell types studied by these techniques. An inner honeycombed layer apparently unique to Amoeba proteus is also described.

scholarly journals ATTACHMENT OF INTRANUCLEAR ANNULATE LAMELLAE TO THE NUCLEAR ENVELOPE

1968 ◽  
Vol 37 (2) ◽  
pp. 540-550 ◽  
Author(s):  
John W. Everingham
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Oocyte Nucleus ◽  
Annulate Lamellae ◽  
Centrifugal Forces

Oocytes of four species of ascidians were examined with the electron microscope. Prior to fixation, oocytes were subjected to centrifugal forces of 10–15,000 g for 5–10 min and were compared with uncentrifuged oocytes. Intranuclear annulate lamellae (IAL) are distributed uniformly around the periphery of the nucleus of the uncentrifuged oocyte. Centrifugation produces a marked flattening of the oocyte nucleus, migration of nucleoli to the centrifugal end, and often a condensation of the nucleoplasm at the centrifugal end. In contrast, the distribution of IAL is unchanged by centrifugation. Furthermore, numerous IAL profiles appear to be touching the nuclear envelope, and, in a few of these, direct continuity of the IAL with the nuclear envelope is demonstrated.

scholarly journals Further Observations on the Nuclear Envelope of the Animal Cell

1959 ◽  
Vol 6 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Michael L. Watson
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Cross Section ◽  
Cross Sections ◽  
Nuclear Membrane ◽  
Animal Cell ◽  
Nuclear Surface ◽  
Apparent Discrepancy ◽  
Outer Nuclear Membrane ◽  
Direct Association

The term pore complex is proposed for approximately cylindrical formations which are observed with the electron microscope to penetrate the nuclear envelope of cells. Cross-sections of the pore complex are somewhat annular in shape, but differ in appearance depending upon the level of the cross-section with respect to the nuclear surface. An explanation is offered for the apparent discrepancy between the width of pores in sections perpendicular to the nuclear envelope and the width of cross-sections of the pore complex in tangential sections. Channels associated with the pore complex extend deep into the nucleus. Although crescents and spirals of ribonucleoprotein particles were often seen in the immediate vicinity of the outer nuclear membrane, direct association with the pore complex was not observed. Many examples were found of pores that were not covered by a continuous membrane although the possibility of such a covering in some cases is not precluded.

Experimental studies on amphibian oocyte nuclei I. Investigation of the structure of the nuclear membrane by means of the electron microscope

1950 ◽  
Vol 137 (888) ◽  
pp. 367-378 ◽  
Keyword(s):  
Electron Microscope ◽  
Porous Layer ◽  
Nuclear Membrane ◽  
Outer Layer ◽  
Pore Diameter ◽  
Experimental Studies ◽  
Separation Distance ◽  
Insoluble Protein ◽  
Amphibian Oocyte

The membrane surrounding the nucleus of the oocytes of two species of amphibian is shown to consist of two structures, an outer porous layer and an inner layer which is apparently continuous. The porous layer is about twice as thick as the inner layer, the dried membrane as a whole having a thickness of approximately 500 Å. The pores are of regular size and arrangement in the outer layer; pore diameter is approximately 400 Å, the separation distance between pore centres 1000 Å. Both layers consist of relatively insoluble protein materials, the porous layer also containing some lipoid.

scholarly journals THE RABBIT ZYGOTE

1972 ◽  
Vol 55 (3) ◽  
pp. 533-541 ◽  
Author(s):  
Bela J. Gulyas
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Smooth Endoplasmic Reticulum ◽  
Annulate Lamellae ◽  
Nuclear Pores ◽  
Late Anaphase ◽  
Dense Nucleus

The formation of the blastomere nucleus was examined in the rabbit zygote with the electron microscope. In late anaphase the chromosomes are bare and vesicles of the smooth endoplasmic reticulum are numerous in the vicinity of the chromosomes. In early telophase individual chromosomes attain their own nuclear envelope and they are called karyomeres. The envelope of the karyomeres contains small gaps within it at several places where the chromatin is exposed to the cytoplasm. Nuclear pores are also observed. In the cytoplasm short annulate lamellae appear adjacent to the karyomeres, and clusters of punctate substance are also present. From early telophase onward the karyomeres extend pseudopod-like structures, called karyopods, which extend toward other karyomeres or karyopods, and consequently fuse together and serve as chromosomal bridges. Eventually all of the karyomeres fuse into a dense nucleus and decondensation of the chromosomes occurs.

Behaviour of annulate lamellae during the maturation of oocytes in the newt, Cynops pyrrhogaster

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 153-169
Author(s):  
Hiroshi Imoh
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Structural Change ◽  
Nuclear Envelope ◽  
Cortical Area ◽  
Close Contact ◽  
Germinal Vesicle ◽  
Annulate Lamellae ◽  
Germinal Vesicle Breakdown ◽  
Progesterone Treatment

The distribution of annulate lamellae, electron-dense masses, rough endoplasmic reticulum, and Golgi complexes in longitudinal sections of newt oocytes at several stages of progesteroneinduced maturation was recorded with an electron microscope equipped with a drawing device. Annulate lamellae in full-grown oocytes occur in close contact with electron-dense masses and the nuclear envelope and elsewhere. Stacks of annulate lamellae increase in number for 6 h after progesterone treatment. Meanwhile, they segregate into three groups. The largest group, comprising about 75% of total stacks, forms a row parallel to and just beneath the oocyte cortex of both the animal and vegetal hemispheres, a second group is distributed in the middle area of the vegetal hemisphere, and a third group appears near the yolk-free cytoplasm formed at the vegetal side of the germinal vesicle during the maturation. About 6 h after progesterone treatment the annulate lamellae begin to disappear at their places of localization and none is found a few hours after germinal vesicle breakdown. No immediate fine-structural change in the cortical area follows the disappearance of subcortical annulate lamellae. The possible origins and fates of annulate lamellae in the maturing newt oocytes are discussed.

scholarly journals Intranuclear membranes and the formation of the first meiotic spindle in Xenos peckii (Acroschismus wheeleri) oocytes.

1983 ◽  
Vol 97 (4) ◽  
pp. 1144-1155 ◽  
Author(s):  
C L Rieder ◽  
R Nowogrodzki
Keyword(s):  
Nuclear Envelope ◽  
Meiotic Spindle ◽  
Annulate Lamellae ◽  
Late Prophase ◽  
Spindle Formation ◽  
Thin Sections ◽  
Tubular Membrane ◽  
The Individual ◽  
Membrane Components ◽  
Bipolar Spindles

The ultrastructure of spindle formation during the first meiotic division in oocytes of the Strepsipteran insect Xenos peckii Kirby (Acroschismus wheeleri Pierce) was examined in serial thick (0.25-micron) and thin sections. During late prophase the nuclear envelope became extremely convoluted and fenestrated. At this time vesicular and tubular membrane elements permeated the nucleoplasm and formed a thin fusiform sheath, 5-7 micron in length, around each of the randomly oriented and condensing tetrads. These membrane elements appeared to arise from the nuclear envelope and/or in association with annulate lamellae in the nuclear region. All of the individual tetrads and their associated fusiform sheaths became aligned within the nucleus subsequent to the breakdown of the nuclear envelope. Microtubules (MTs) were found associated with membranes of the meiotic apparatus only after the nuclear envelope had broken down. Kinetochores, with associated MTs, were first recognizable as electron-opaque patches on the chromosomes at this time. The fully formed metaphase arrested Xenos oocyte meiotic apparatus contained an abundance of membranes and had diffuse poles that lacked distinct polar MT organizing centers. From these observations we conclude that the apparent individual chromosomal spindles--seen in the light microscope to form around each Xenos tetrad during "intranuclear prometaphase" (Hughes-Schrader, S., 1924, J. Morphol. 39:157-197)--actually form during late prophase, lack MTs, and are therefore not complete miniature bipolar spindles, as had been commonly assumed. Thus, the unique mode of spindle formation in Xenos oocytes cannot be used to support the hypothesis that chromosomes (kinetochores) induce the polymerization of their associated MTs. Our observation that MTs appeared in association with and parallel to tubular membrane components of the Xenos meiotic apparatus after these membranes became oriented with respect to the tetrads, is consistent with the notion that membranes associated with the spindle determine the orientation of spindle MTs and also play a part in regulating their formation.

Membranous alterations in the cytoplasm and nucleus in a primitive neuroectodermal tumor of the brain

1978 ◽  
Vol 36 (2) ◽  
pp. 628-629
Author(s):  
C. N. Sun ◽  
C. Araoz ◽  
H. J. White
Keyword(s):  
Nuclear Envelope ◽  
Tumor Cells ◽  
Osmium Tetroxide ◽  
Primitive Neuroectodermal Tumor ◽  
Uranyl Acetate ◽  
Neuroectodermal Tumor ◽  
Annulate Lamellae ◽  
Lead Citrate ◽  
Thin Sections ◽  
The Brain

The ultrastructure of a cerebral primitive neuroectodermal tumor has been reported previously. In the present case, we will present some unusual previously unreported membranous structures and alterations in the cytoplasm and nucleus of the tumor cells.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4% glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1% buffered osmium tetroxide for one hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate.In the cytoplasm of the tumor cells, we found paired cisternae (Fig. 1) and annulate lamellae (Fig. 2) noting that the annulate lamellae were sometimes associated with the outer nuclear envelope (Fig. 3). These membranous structures have been reported in other tumor cells. In our case, mitochondrial to nuclear envelope fusions were often noted (Fig. 4). Although this phenomenon was reported in an oncocytoma, their frequency in the present study is quite striking.

PREPARING PUBLIC SERVANTS IN EUROPEAN COUNTRIES: ARCHETYPAL APPROACH

2018 ◽  
Vol 1 (14) ◽  
pp. 255-263
Author(s):  
Oleh Ivanovich Rohulskyi
Keyword(s):  
Public Administration ◽  
Public Service ◽  
Professional Training ◽  
European Countries ◽  
Anglo Saxon ◽  
Public Servants ◽  
German Model ◽  
Managerial Positions ◽  
A Chain ◽  
The Individual

The article describes the main components of the institutional framework of an archetypical approach to public administration. It is determined that the system of preparation of public servants is based on a chain of universal foundations of archetype, in particular, it is influenced by the principle of formation of personnel in the public service, formed on the basis of public opinion. Based on two basic principles relating to admission to public service, three basic models of training civil servants in the European country are defined: German. French and Anglo-Saxon. We analyze each of the models and define the archetypes that influenced their formation and development. The advantages of each model are determined, in particular, the benefits are: the German model of training managers is the balancing between the theoretical knowledge and practical skills that a public servant receives during training, but as a disadvantage one can distinguish the orientation of preparation for legal orientation, which limits the ability to hold managerial positions for many employees The French model of professional training of public servants should include a well-balanced understanding of tasks, namely: decentralization and territorial organization of public services, communication, support of territorial communities, in-depth knowledge and understanding of the need for cooperation with institutions of the European Commonwealth, high-quality human resource management and orientation towards environmentally friendly innovations, such a model of training of public servants is holistic, costly and effective; The Anglo-Saxon model of training of public servants is its orientation towards the implementation of the concept of public administration and the individual approach to employee training, taking into account all the specifics of its activities, providing for the formation of personnel capable of solving specific problems. It is concluded that today in most European countries dominated by mixed models that include elements of different models.

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