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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 30 (1983), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Gossypol, a polyphenolic compound from the cotton plant, immobilizes and structurally alters cultured Trypanosoma cruzi epimastigotes. Ultrastructural changes observed in gossypol-treated parasites were first detected in the kinetoplast and mitochondrion. At 50 μM concentration, much disorganization was evident after 5 min of incubation. With 25 μM gossypol, the same effect occurred after 30 min. Most epimastigotes were rounded, containing various membranous structures that could not be related to known cell components.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 37 (1990), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Bloodstream Trypanosoma cruzi trypomastigotes isolated from infected mice undergo reduction of motility and structural damages after 5 to 45 min exposure to gossypol at concentrations ranging from 5 to 50 μM. When 1% serum albumin is added to the incubation medium, no alterations of parasites are observed, even with 100 μM gossypol. Intracellular T. cruzi amastigotes in infected Vero cell cultures exposed to 5 μM gossypol for 2 h do not show changes. Incubation with 5 μM gossypol for 48 h produces complete disruption of host cells; however, the amastigotes they contain show only mineor alterations. The observations indicate that, in protein-rich media, gossypol is complexed into associations which have no activity on the different forms of the T. cruzi biological cycle.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 171 (1985), S. 71-74 
    ISSN: 1432-0568
    Keywords: Placenta (guinea pig) ; Umbilical vessels ; Perfusion fixatives ; Tracers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A surgical procedure was developed for cannulation of umbilical vessels in the guinea pig placenta. This approach allows an administration of electron opaque tracers, perfusion of fixatives and injection of corrosion casting compounds with minimal disturbance to the fetus and the placenta.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 129 (1969), S. 135-153 
    ISSN: 1432-0568
    Keywords: Guinea pig-Testis ; Spermatozoa excretion ; Rete testis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The seminiferous tubules are continuous with a short and narrower tubule, the intermediate region, lined by cylindrical Sertoli-like cells; these contain mitochondria, granules, vacuoles, cisternae, lysosomes and fibrils. The epithelium abruptly becomes low and cuboidal in the tubuli recti, where the cells have no apical differentiations and contain only few granules, cisternae and mitochondria. The tubuli recti open in a labyrinth of interconnected spaces, the rete testis, which has two main parts: one, near the ductuli efferentes, is the mediastinal rete testis, the interstitium of which has abundant connective tissue fused with the tunica albuginea testis; by contrast, the interstitium of the peripheral rete testis, next to the tubuli recti, contains numerous Leydig cells. The epithelium in both segments is quite similar, low and cuboidal, with mitochondria, some vacuoles and lysosomes. Very few, irregular microvilli and occasional cilia were found in the apical border. The typical limiting membrane of the seminiferous tubules is found also in the intermediate region, the tubuli recti and the peripheral rete testis. In the mediastinal rete testis, instead of this limiting complex, there is only a basal lamina. In the intermediate region we did not find the plugs described by other workers. Furthermore our morphological evidence does not support the concept of an important active transport in the rete testis.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 171 (1985), S. 297-304 
    ISSN: 1432-0568
    Keywords: Placenta (guinea pig) ; Permeability ; Freeze-Tracturing ; Ultrastructure ; Cell junctions ; Tracers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Permeability of the fetal endothelium within the guinea pig placental labyrinth is studied by means of horse-radish peroxidase (HRP) and ionic lanthanum as diffusion tracers. The paracellular transport of HRP is restricted by the occluding junctions of the fetal endothelium. In contrast, ionic lanthanum readily permeates most of the intercellular junctions and rapidly infiltrates the basal lamina. Freeze-fracture replicas reveal zonulae occludentes connecting the fetal endothelial cells. The network of the zonulae occludentes is variable, exhibiting highly complex areas as well as single strand interconnections. A correlation between the permeability studies and freeze-fracture findings is discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 176 (1987), S. 525-530 
    ISSN: 1432-0568
    Keywords: Placenta ; Guinea pig ; Labyrinth ; Syncytiotrophoblast ; Tracers ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The permeability of the materno-fetal barrier in the chorioallantoic placenta was studied in guinea pigs with gestation at term applying a variety of electron-opaque tracers via maternal circulation. None of the tracers tested was seen permeating the syncytiotrophoblast in the materno-fetal direction up to a 20 min interval when the fine structure of the placenta was satisfactorily preserved. The lanthanum chloride, cationized ferritin and horseradish peroxidase bound to the trophoblast surface, apparently due to electrostatic forces more than to specific receptors, and no uptake of these probes was detected in the cytoplasm. Albumin-colloidal gold complex, also used as a tracer, yielded similar results. As reported in other species with more complex syncytiotrophoblastic organization, this layer investing maternal lacunae is a highly selective permability barrier.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 30 (1980), S. 87-91 
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Electrophoretic patterns of lactate dehydrogenase (EC 1.1.1.27) from adult testes show the existence of three different phenotypes for the isozyme X or C4 in populations of racing homer pigeons. These phenotypes are the expression of two different alleles at the Ldh c locus. Analysis of electrophoretic patterns of lactate dehydrogenase from lysates of mature spermatozoa isolated from pigeons heterozygous at the Ldh c locus indicates that the two different alleles are expressed in haploid cells. It is concluded that transcription of the gene coding for isozyme X must occur only in pre-meiotic cells.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 291 (1998), S. 571-574 
    ISSN: 1432-0878
    Keywords: Key words Apoptosis ; Cell death ; DNA fragmentation ; Pituitary gland ; Ventral prostate ; TUNEL labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The proliferation of cells and cell death are involved in the maintenance of appropriate tissue homeostasis. In the present study, two different mechanisms of cell death were identified in the prostate and pituitary glands when morphological data, fragmentation of DNA, and TUNEL labelling of apoptotic nuclei were compared. Typical cell death by apoptosis was identified by morphological and molecular approaches in the prostate after orchidectomy. By contrast, neither DNA fragmentation nor TUNEL labelling were found in dead cells occurring in the pituitary gland after interruption of lactation. Regressing lactotrophs were characterised by condensation and disruption of the cytoplasmic matrix, but preserved intact nuclei until advanced stages of regression. Degenerating “dark” cells comparable to those described in the pituitary were also seen coexisting with typical apoptosis in the prostate epithelial lining of orchidectomised rats. Both forms of cell death could be clearly differentiated, because dark cells suffer severe alterations of cytoplasmic organelles while maintaining the integrity of the nucleus. In contrast, apoptotic cells present well-preserved cytoplasmic organelles, but grossly disrupted nuclei with fragmentation and condensation of chromatin.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 98 (1969), S. 9-16 
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the interstitial tissue of the testis of Physalaemus fuscumaculatus is described. Epithelioid cells identified as Leydig cells occur scattered in the interstitial tissue. Their cytoplasm contains a well developed smooth and rough surfaced endoplasmic reticulum arranged in whorls. The mitochondria present typical tubular cristae and unusual inclusions of a granular material. In spite of the distinctive characteristics reported here, it is assumed that the function of the Leydig cells is basically similar to that of the steroid synthetizing cells of the testicular interstitial tissue of higher vertebrates. An unusual feature is the presence of numerous melanophores randomly distributed in the capsule of the testis and in the interstitium. They are polyhedric cells with poorly developed organelles, numerous melanosomes, and long cytoplasmic processes. A large amount of collagen is present in the intercellular spaces closely related with undifferentiated cells, most of which are assumed to be fibroblasts.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 141 (1973), S. 293-305 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The gular gland of the bat Tadarida brasiliensis is a specialized sebaceous gland located in the skin of the suprasternal region of adult males. It consists of an aggregation of simple branched tubulo-acinar gland units, the number of which varies seasonally. Each acinus is composed of densely packed sebaceous cells at various stages of differentiation. Acinar basal cells and cells of the epithelium of the ducts can differentiate into sebaceous cells. Two main changes appear in the cytoplasm concurrent with the sebaceous transformation: the differentiation of cytoplasmic organelles and the deposition of lipid material. The appearance of a different type of mitochondrion and the development of large numbers of ribosomes and polyribosomes can be recognized in the cytoplasm at an early stage of differentiation. Concomitant with the deposition of significant numbers of lipid droplets, the cells develop abundant agranular endoplasmic reticulum occurring mainly as scattered tubular cisternae. These at times form whorls surrounding lipid droplets. At later stages, the cisternae of the agranular endoplasmic reticulum often occur in crystalline arrays between secretory oil droplets. The roles of the different cytoplasmic organelles, especially in relation to the production of sebum, are discussed.
    Type of Medium: Electronic Resource
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