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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 9 (1962), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Chilomonas paramecium has been studied by light and electron microscopy with special attention to the so-called trichocysts. The electron miscroscope reveals that the anatomy of these bodies is unlike that of the classical trichocysts of ciliates. Since these structures can be extruded from the body of the organism they have been called ejectisomes. The ejectisomes have a regular geometrical shape and a complex internal structure. They consist of two unequal components which are enclosed by a thin membrane. Morphological polarity is established by an anterior smaller unit and a posterior larger unit. When the ejectisomes are found in the peripheral cytoplasm or in a perivestibular position the smaller unit is always oriented toward the surface. A suggestion is made that the ejectisomes are derived from the vesicular component of the Golgi complex. An interpretation is offered concerning a mechanism by which ejectisomes may be extruded from the body.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 2 (1955), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. Thin sections of Trichomonas muris, from the caecum of Mesocricetus auratus, were observed with the aid of the electron microscope in order to determine structural details of organelles of this species.The blepharoplast appears to be limited by a membrane. What seem to be basal granules occur in the blepharoplastic area for the axostyle and the lamellae of the undulating membrane and measure approximately 500 Å in diameter.In cross section the anterior flagella and posterior flagellum are composed of eleven fibrils, two centrally and nine peripherally located. Each fibril measures about 380 Å in diameter.The so-called “accessory filament” of the undulating membrane is devoid of any filamentous structure and appears to be composed of two differentiated mesh-work areas. The undulating membrane is composed of a series of lamellae ranging from 300 to 400 Å in thickness. This organelle is attached to the external body surface by fine fibers ranging from 167 to 300 Å in thickness.The costa consists of a series of disks embedded in a matrix. The costa is attached to the internal body surface by what appear to be extensions of the costal disks. These disks are approximately 370 Å in thickness and spaced 490 Å apart.The axostyle is limited by a double, corrugated membrane. The corrugations are about 150 Å in thickness and spaced 110 Å apart. The so-called chromatic ring is composed of a series of rods approximately 640 Å in thickness.The parabasal body consists of a series of filaments approximately 190 Å in thickness.Mitochondria, spheroidal in shape, are limited by a membrane about 180 Å in thickness. The internal structure consists of a varying number of projections which make this organelle appear in section as a series of compartments.Chromatic granules (paracostal, para-axostylar, endo-axostylar and those scattered in the cytoplasm) are irregular in shape and limited by a membrane approximately 200 Å in thickness. These granules typically display a vacuolated internal structure.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 8 (1961), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Electron micrographs of sections through the blepharoplast complex reveal it to be composed of four kineto-somes. In many of the sections the kinetosomes contain dense particles approximately 180-200 A in diameter. The costa is a striated fiber which extends posteriorly almost the entire length of the body. Its slender proximal portion appears to be attached to the base of the kinetosome of the recurrent flagellum. The parabolas fiber is similarly constructed, but is more slender than the costa. It is attached to the base of the kinetosome of an interiorly directed flagellum and subsequently proceeds posteriorly to the level of the nucleus. The costa and parabasal fiber probably serve as anchoring or supportive structures. The size of the costa may reflect its role as a supporting structure for the most highly differentiated locomotors organelle, the undulating membrane.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 7 (1960), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Actinosphaerium nucleofilum has been studied by light and electron microscopy. Thin sections of this organism reveal the relatively compact endoplasm to consist of numerous vacuoles and mitochondria. Scattered in the cytoplasm are dense particles, presumably ribonucleoprotein particles, endoplasmic reticulum of the rough variety and a tubular endoplasmic reticulum of the smooth variety. The many nucleido not appear to be randomly scattered in the cytoplasm but rather to be arranged in a circular pattern. Each is bounded by a double membrane envelope. A Golgi complex, consisting of isolated bodies with an ultrastructure similar to that described by others, is usually seen associated with each nucleus.The ectoplasm contains many vacuoles of varying diameter, each of which is limited by a thin membrane; vacuoles containing dense granular material, and mitochondria.The radially arranged axiopodia are extensions of the ectoplasm. The periphery is largely composed of vacuoles, some of which contain dense granules, and mitochondria. The axial rod is birefringent and consists of many fine filaments oriented parallel to the longitudinal axis of the axiopodium. The constituent filaments penetrate deep into the endoplasm where they end in the vicinity of nuclei. The fibrillar component of the axiopodia may represent contractile units.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 6 (1959), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Materials within the endoplasm of both the protomerite and deutomerite may be displaced and stratified by ultracentrifugation. Animals are not killed by this treatment, and in time a redistribution of stratified materials may occur. The electron microscope reveals numerous ultramicroscopic folds in the surface envelope which is composed of 3 membranes; the outer and middle cover the surface of the folds while the inner one continues as a smooth membrane over the ectoplasm. The contact surfaces of animals in syzygy do not show the small folds to be interlocked; instead, they are in fold-to-fold contact. Numerous relatively dense bodies which appear to be filamentous are sometimes observed immediately underneath or within the middle or inner membrane. Within the ectoplasm is an ultramicroscopic net-like fibrillar structure much denser than the surrounding cytoplasm. This system of fibrils is composed of anastomosing elements varying from ∼ 50 to 200 Å in diameter. Certain of the larger fibrils are directly attached to the surface envelope at positions between the folds. A second filamentous structure within the ectoplasm appears to be tubular. Elements of this system also appear to join and penetrate the surface envelope by means of pores.A large amount of gelatinous secretion forms at the surface of the sporont; as it glides forward a trail of mucous is left behind. The actual mechanism involved in the gliding movement was unobserved, but evidence is lacking to support the view that the gliding movement is engendered by posteriorly directed “jets” of mucus.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 95 (1969), S. 495-510 
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The techniques of light and electron microscopy have been employed in a study of the protective coverings of the egg of Drosophila melanogaster. Data obtained during this investigation suggest the involvement of the follicle cells, in the production of one of these coverings and justify its classification as a secondary coat. The secondary coat of D. melanogaster is highly organized and has been divided into three Zones (I, II, IIII). The follicle cells enveloping the oocyte exhibit two phases of secretory activity each involving hypertrophy of the Golgi complex and rough endoplasmic reticulum, and the production of protein and polysaccharide components. The first phase concerns the elaboration of the material which gives rise to the homogeneous lamina referred to as Zone I. The second results in the release of an electron dense component which becomes organized into two laminae separated by struts or pillars; this construction is referred to as Zone II. At the completion of this secretory phase, the follicle cells assume a squamous morphology and a third Zone, composed of a homogeneous substance, appears between the follicle cells and Zone II.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 231 (1991), S. 185-192 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This investigation was designed to study ovarian and hormonal changes in the after treatment with dehydroeplandrosterone (DHEA). We identified a heterogeneous experimental group of animals with respect to ovarian histology: group I, corpora lutea (Cls) + cysts; group II, CLs + no cysts; group III, no CLs + cysts; group IV, no CLs + no cysts. Histological sections of these ovaries showed healthy and atretic follicles in different stages of cytomorphosis and degeneration. The aforementioned histological groups were also heterogeneous according to their hormonal profiles. Serum androgens, estrogens, and prolactin concentrations are significantly increased in DHEA-treated animals as compared with controls. There was no significant difference in follicle stimulating hormone between the with cysts and rats without cysts after DHEA treatment. After 20 days of DHEA treatment, rats with CLs have very high levels of luteinizing hormone. Luteinizing hormone and prolactin levels are significantly higher in rats with cysts than in rats without cysts after 10 days of DHEA treatment. As has been shwon in this inquiry, androgens and estradiol levels in rats with cysts after DHEA treatment are higher than those in rats without cysts after DHEA treatment. Therefore, this study suggests that the ovarian cystic condition developed after DHEA treatment in rats, is associated with higher levels of circulating androgens, estradiol, and prolactin.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0003-276X
    Keywords: Rat ; DHEA ; Ovarian follicular cyst ; Ultrastructure ; Androgens ; Estrogens ; Prolactin ; Radioimmunoassay ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Immature 27-day-old female Sprague-Dawley rats were administered daily subcutaneous injections of dehydroepiandrosterone (DHEA, 5 mg/100 g BW) to induce the formation of ovarian follicular cysts. Groups of rats were killed on days 0, 10, 15, 20, 25, and 30. Ovaries from each group of rats were processed for light and electron microscopy and for follicular or cystic fluid hormone analysis. Normal antral follicle fluid, PMSG-treated preovulatory follicular fluid, and cystic fluids were analyzed for progesterone (P), estrone (E1), estradiol (E2), testosterone (T), Δ4-androstenedione (Δ4-A), 5α-dihydrotestosterone (DHT), luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PRL).DHEA induced anovulation, acyclicity, and the formation of follicular cysts. In certain antral follicles, there was a dramatic increase in the quantities of smooth endoplasmic reticulum (SER) in the granulosa cells and many mitochondria had tubular cristae. Further depletion of granulosa cell number was associated with intense blebbing of the cytoplasm into the follicle antrum. Formation of the ovarian follicular cyst was completed when the entire cyst was lined by a single layer of transformed granulosa cells in contact via adhering, gap, and tight junctions. These cells had little cytoplasm, mitochondria with lamellar cristae, vast basal and apical bands of microfilaments, and an extensive array of smooth-surfaced endocytotic invaginations on the basal plasma membrane. These endocytotic pits may subsequently form smooth-surfaced vesicles and thereby serve as one mechanism for moving fluid from the ovarian interstitium into the cyst. Theca interna cells were rarely observed in the peripheral regions of the cyst. Abundant smooth muscle cells were located beneath the basement membrane of the epithelial cells comprising the cyst wall. These acquired morphological and physiological features may ensure persistence of the ovarian cyst and thus potentiate a chronic pathological condition.In this study it was also shown that progesterone, estrone, and estradiol as well as androgen concentration increased in the follicle after PMSG treatment. With DHEA treatment, the follicular cystic fluid concentrations of these steroids progressively increased to extremely high levels concurrent with the development of the follicular cysts. With respect to pituitary protein hormones, there was no appreciable difference in FSH after PMSG treatment, while there was a decrease in LH and an increase in PRL.The information reported in this and a previous study (Lee et al., Anat. Rec., 231:185-192, 1991) suggests that the ovarian cystic condition that developed after DHEA treatment in rats is associated with elevated levels of circulating serum prolactin and androgens, and extremely high concentrations of steroids as well as FSH and LH in the follicular/cystic fluid.© Willey-Liss, Inc.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: By use of lanthanum tracer and freeze-fracture procedures it was found that granulosa-lutein cells of the pregnant mouse and rat ovaries are connected by gap junctions and septate-like zones of contact. Lutein cell gap junctions enlarge and become partially internalized by the end of the first week of gestation. Expansion of the gap junction domain appears to be due initially to intercalation of particles along borders of small gap junctions devoid of smaller non-junctional particles. The number of gap junction lined processes appearing at the cell border increases concomitantly with hypertrophy of the lutein cell during the second week of pregnancy. Strands of particulate or grooved membrane emanate from the margin of larger gap junctions undergoing interiorization. Most large gap junctions are intimately associated with elements of the smooth endoplasmic reticulum. Spherical gap junctional profiles assume a deeper location in the lutein cell and may form concentric arrays by term while true surface gap junctions appear to fragment in the post-partum corpus luteum. The modifications observed are interpreted with respect to biogenesis of the gap junction and the hormonal control of lutein cell function.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 214 (1981), S. 181-193 
    ISSN: 1432-0878
    Keywords: Gap junctions ; Hormonal modulation ; Rat ovary ; Granulosa cells ; Thecal cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Homocellular gap junctions between granulosa cells and between theca interna cells, and heterocellular gap junctions between granulosa cells and oocytes persist in rat ovarian follicles for as long as 90 days following hypophysectomy. Gonadotrophic and/or steroid hormones are therefore not required for the maintenance of gap junctions between these cells during early follicular growth. However, replacement therapy with estrogen and human chorionic gonadotrophin results in amplification of gap junctions in granulosa and theca interna cells respectively. Within 24 h following hormonal stimulation, growth of gap junctions is characterized by the appearance of formation plaques as observed in freeze-fracture replicas and by the association of microfilamentous material located subadjacent to gap junction membrane observable in thin-sectioned cells.
    Type of Medium: Electronic Resource
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