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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 180 (1989), S. 207-212 
    ISSN: 1432-0568
    Keywords: Thyrotroph (TSH cell) ; Anterior pituitary ; Immunogold electron microscopy ; Postnatal development ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thyrotrophs (TSH cells) of the rat anterior pituitary identified by immunogold electron microscopy were classified into three subtypes according to their morphological characteristics: Immature type TSH cells are oval with a few small secretory granules (50–100 nm in diameter) and poorly developed cell organelles. These cells are frequently found in the neonatal stage between birth and 10 days of age. The intermediate type is polygonal or stellate, containing a moderate number of medium sized secretory granules (80–120 nm in diameter) and moderately or well developed cell organelles. Cells of this type are often found between 10 and 30 days of age. Mature type cells are large and polygonal in shape, and contain many large secretory granules (120–180 nm in diameter) and well developed cell organelles. Cells of the last type are frequently found at more than 30 days of age. At 45 days of age the mature type TSH cells make up about 70% of all TSH cells. The proportion of immature type cells was shown to decrease while the proportion of the mature type TSH cells increases, as the animal grows.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: α-Subunit ; Pituitary glycoprotein hormone ; PRL cell ; Pars distalis ; Colocalization ; Immunocytochemistry ; Bullfrog, Rana catesbeiana (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Our recent finding that the number of immunoreactive α-subunit cells was invariably greater than the total number of immunoreactive gonadotropin (GTH) and thyrotropin (TSH) cells in the bullfrog (Rana catesbeiana) pituitary gland raises the possibility that the α-subunit also exists in pituitary cells other than GTH and TSH cells. The present study demonstrates that there are a considerable number of immunoreactive prolactin (PRL) cells that are also stained with antibody against the α-subunit when adjacent sections are immunocytochemically examined. Neither immunoreactive growth hormone nor adrenocorticotropin cells are stained with the antibody against the α-subunit. The specificity of the antibody against the α-subunit and of that against PRL was demonstrated by preabsorption test, non-competitive binding test, and immunoblot analysis. Double-immunolabeling with gold particles of different sizes for the α-subunit and PRL revealed that most of the immunolabeled PRL-secretory granules are also labeled with the α-subunit antibody. The gold particles indicating the presence of the α-subunit were mostly found in the peripheral zone of the secretory granules.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0878
    Keywords: Anterior pituitary ; Prolactin cell ; TRH ; T4 ; Thyroidectomy ; Immuno-electron microscopy ; Morphometry ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract An immunoelectron-microscopic and morphometric study was carried out on the anterior pituitary prolactin (PRL) cells of adult male Wistar rats treated with a combination of thyroidectomy and administration of L-thyroxine (T4) and/or synthetic thyrotropin-releasing hormone (TRH) in order to clarify the effects of changes in the hypothalamus-pituitary-thyroid axis on the ultrastructure and function of PRL cells. After thyroidectomy, PRL cells underwent atrophy and hypofunction of their cell organelles, but these changes tended to be restored to their normal level by T4 treatment. On the other hand, the administration of TRH to intact rats produced hypertrophy and hyperfunction in the PRL cells, although this treatment had no effect on the PRL cells of thyroidectomized rats. However, treatment with a combination of T4 and TRH had a strong effect and led to hypertrophy and hyperfunction in the PRL cells of thyroidectomized rats. Serum and pituitary PRL levels were measured by radioimmunoassay (RIA) for a comparison with the morphological results. They correlated well with the morphological changes. These results indicate that TRH stimulates PRL secretion in the presence of thyroid hormone, and that the thyroid hormone plays an important role in the basic maintenance of PRL cell function and its reactivity to TRH.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Persistent estrus and diestrus was produced in rats by the administration of estrone for either 5 days or 30 days, respectively, immediately after birth. Female rats without any treatment were used for control. After these rats grew up, the anterior pituitaries were examined by electron microscopy. The identification criteria for two types of gonadotrophs, FSH-and LH-cells, proposed by Barnes were adopted. In the persistent estrous rats, FSH-gonadotrophs were almost normal, but LH-gonadotrophs were filled with an abundance of secretory granules which were probably suppressed in discharge. On the other hand, in the persistent diestrous rats, FSH-cells were few in number and strongly atrophic, containing a few secretory granules, while LH-cells were almost normal or rather slightly activated. These electron microscopic findings well coincide with the results of light microscopy of ovaries, which suggested that in the persistent estrous rats FSH secretion might be almost normal but the secretion of LH might be inhibited, while in the persistent diestrous rats FSH secretion might be almost totally abolished but LH might be moderately secreted. From these findings, identification of FSH-and LH-gonadotrophs in the anterior pituitary of the rat well coincides with that proposed by Barnes in mice.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A well-developed plate-like cisterna (PLC) associated with trans-Golgi elements was observed in the Golgi apparatus of secretory cells in the rat anterior pituitary gland. This structure corresponds to the trans-most sacculotubular network. The PLC maintains a remarkably uniform thickness of about 33 nm, as measured between the outer leaflets of its unit membrane structure. As to the mechanism by which this peculiar construction of the PLC is maintained, pillar-like structures were noted in the PLC intracisternal space, apparently acting as supports to keep the intermembrane distance constant. The PLC was especially well developed in hypertrophied cells such as gonadotrophs following castration. One noteworthy feature was that the PLC frequently ran parallel with the rough endoplasmic reticulum (RER), maintaining a constant distance from the latter in hypertrophied cells, but no membrane continuity between the PLC and RER was seen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0878
    Keywords: Paraventricular nucleus ; Rat ; Types of neurons ; Secretory cycle ; Herring body
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the neurosecretory cells in the paraventricular nucleus of the normal male rat was studied by electron microscopy during various functional states. Four morphologically distinct types of neurosecretory cells were observed. It appears that they do not represent different classes of cells but different phases of secretory activity of a single cell type. The perikarya of the neurosecretory cells show a definite cycle of formation and transportation of secretory granules. We have designated the phases of this cycle as: (1) phase of synthesis, (2) phase of granule production, (3) phase of granule storage and (4) phase of granule transport. The neurosecretory granules appear to be moved in bulk into the axons, forming a large axonal swelling filled with granules as a result of one cycle in the neurosecretory process. Thus it may be postulated that a secretory cycle in the perikaryon of the neurosecretory cell seems to result in the formation of a Herring body in its axon, and that its content is then conveyed to the posterior pituitary.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 240 (1985), S. 271-276 
    ISSN: 1432-0878
    Keywords: Pituitary ; Castration ; Gonadotropes ; Mitosis ; Testosterone replacement ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The proliferation of gonadotropes in the anterior pituitary of the castrated male rat was examined immunohistochemically after colchicine treatment. The results show a more than 10-fold increase in mitotic frequency in gonadotropes 1 or 2 weeks after castration, as compared with controls. This result explains the increase in the population of immunoreactive LH cells in castrated male rats. The gonadotropes decreased significantly 1 month after castration. The mitotic activity of gonadotropes was almost completely suppressed in castrates implanted with a silastic tube filled with testosterone.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 243 (1986), S. 229-238 
    ISSN: 1432-0878
    Keywords: Anterior pituitary ; Corticotropes ; α-MSH ; Immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Specific antisera to α-melanotropin (α-MSH) and corticotropin (ACTH 1-39) were used to obtain immunocytochemical evidence for the differential localization of α-MSH and ACTH in the secretory granules of corticotropes of rat anterior pituitary. The specificity of the antisera was established by binding 131I-labeled α-MSH and ACTH 1-39 to their respective antisera. Double-labeling immunocytochemistry (for α-MSH, ferritin; for ACTH, colloidal gold) was performed. Some secretory granules were labeled with ferritin particles (α-MSH), whereas others contained gold particles (ACTH). Only a few granules showed both ACTH and α-MSH. In typical corticotropes (stellate in form with a small number of secretory granules aligned along the cell periphery) only some of the secretory granules that were labeled with anti-ACTH serum were also immunoreactive to anti-α-MSH. In atypical corticotropes (polygonal in shape and containing a large number of secretory granules) almost all of the immunoreactive ACTH secretory granules were also positive to anti-α-MSH serum. An intermediate type of corticotrope was observed containing a small number of secretory granules, almost all of which were labeled with anti-α-MSH. Thus, rat anterior pituitary corticotropes may be classified into three types according to the distribution and content of α-MSH. The light-microscopic immuncytochemistry provided similar results.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 235 (1984), S. 77-83 
    ISSN: 1432-0878
    Keywords: Pituitary (rat) ; LH cells ; FSH cells ; Rapid freeze-substitution ; Immunocytochemistry ; Ferritin antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rapid freeze-substitution fixation was employed in immunocytochemical studies on the localization of LH and FSH in the typical gonadotrophs of the anterior pituitary in the untreated male rat; a modification of a recently described ferritin antibody method (Inoue et al. 1982) was used in these studies. It was shown that rapid freeze-substitution fixation provides good preservation not only of the ultrastructure but also of the antigenicity. Both LH and FSH were clearly demonstrated in the same gonadotrophic cells, but the subcellular localization of these gonadotrophins differed: (i) LH was mainly located in small secretory granules, 250–300 nm in diameter; (ii) FSH was mainly present in large secretory granules, up to 500 nm in diameter. In the pituitary gland of the adult male rat, all gonadotrophs that react to antibodies against gonadotrophins are characterized by small and large secretory granules. Other types of cells of the anterior pituitary containing either small secretory granules or resembling corticotrophs with secretory granules assembled at cell periphery did not react to either anti-LH beta or anti-FSH beta serum. For light microscopy, the peroxidase antibody method was used. All of the gonadotrophin-positive cells contain both LH and FSH. None of the pituitary cells reacted to antibody against only one gonadotrophin. However, some cells are “LH-rich” while other cells are “FSH-rich”.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 42-56 
    ISSN: 0741-0581
    Keywords: Immunoelectron microscopy ; Anterior pituitary ; Pars intermedia ; Cryo-ultramicrotomy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Immunocytochemistry has made great strides in the morphology of endocrine glands, especially the adenohypophysis, because the localization of hormones can be clearly demonstrated by this method in the microscopic preparations both for light and electron microscopy. In the adenohypophysis, electron microscopic immunocytochemistry is useful for identifying the producer cell of each hormone. The second contribution is its application to the cell biology of secretion mechanisms. The pituitary hormones, their precursors, derivatives, and fragments were artificially synthesized and their antibodies were produced. Using these antibodies the intracellular sites of synthesis, condensation, processing, and sorting were studied under the electron microscope. The ultrastructure of each cell organelle and its alteration due to the changing function was studied. It was proved that the intracisternal granules in the thyroidectomy cells contain thyroid-stimulating hormone (TSH). The trans-Golgi network or GERL contains a peculiar supporting structure, intracisternal skeleton. Transport of secretory granules may be performed in relation to the microtubules, actin, and some related substances. The most frequently observed mode of hormone release in the adenohypophysis is exocytosis. Sometimes multigranular exocytosis occurs. Vesiculation of membrane around the secretory granules often occur inward or outward. The inward vesiculation forms pinocytotic vesicles, through which the membrane material may be retrieved. The outward vesiculation forms vesicle-like fragments of cytoplasm being discarded to the extracellular space. By these mechanisms the surface area of the cell is maintained constantly.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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