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  • 1
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Spermatogenesis is a complex process that involves cooperation of germ cells and testicular somatic cells. Various genetic disorders lead to impaired spermatogenesis, defective sperm function and male infertility. Here we show that Cnot7−/− males are sterile owing to ...
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The proper folding of newly synthesized membrane proteins in the endoplasmic reticulum (ER) is required for the formation of functional mature proteins. Calnexin is a ubiquitous ER chaperone that plays a major role in quality control by retaining incompletely folded or misfolded proteins. In ...
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  • 3
    ISSN: 1432-0568
    Keywords: Atrial specific granule ; Atrial natriuretic polypeptide ; Impulse conducting system ; Immunohistochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study was performed to clarify the distribution of ANP-containing cells in the adult rat heart by immunostaining for ANP using antiserum against α-human ANP. ANP-immunoreactive cells were generally present in the atrial walls except for the sinoatrial node. In the ventricular walls, they were distributed in the impulse conducting system, particularly the left bundle branch, Purkinje fibers on the left side of the interventricular septum, and those in the false tendons in the left ventricle, while they were sporadically seen in the atrioventricular node and bundle of His. The immunoreactive cells contained specific granules that were positive for ANP. These findings demonstrate that ANP-containing cells are present in the atrial and ventricular walls.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 114 (2000), S. 181-189 
    ISSN: 1432-119X
    Keywords: Glycoprotein Spermatocytes Spermatogenesis Testis Monoclonal antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. We produced a monoclonal antibody, designated MC301, against the extract of testicular cells from 12-day-old rats. This age corresponds to the onset of meiosis during testis development. MC301 specifically recognized a 90-kDa glycoprotein, GP90-MC301, which was ubiquitously expressed in various tissues and localized predominantly in the Golgi area of epithelial cells. In adult testes, stage-specific intense expression of GP90-MC301 was shown in the cytoplasm of meiotic spermatogenic cells from the preleptotene to mid-pachytene stages. Immunoelectron microscopy demonstrated that the glycoprotein was localized in spermatocytes on protein synthesis-related organelles such as the Golgi apparatus, endoplasmic reticulum, and nuclear envelope. The plasma membrane of spermatocytes and the intercellular space surrounding the cells were also immunoreactive. No specific immunoreactivity was found on the organelles in other testicular cells. A considerable amount of the glycoprotein was detected in the extracellular fluid of the testes. These results suggest that GP90-MC301 is produced mainly by spermatocytes in the testis and secreted into the surrounding intercellular space. The evidence for developmentally regulated expression of GP90-MC301 in the meiotic spermatogenic cells suggests a possible role for the glycoprotein in male germ cell meiosis.
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  • 5
    ISSN: 1432-0878
    Keywords: Heart ; Atrial-specific granules ; Atrial natriuretic polypeptide ; Immunohistochemistry ; Impulse-conducting system ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An immunohistochemical study of atrial natriuretic polypeptides was carried out on embryonic, fetal and neonatal rat hearts, using an antiserum raised against α-human atrial natriuretic polypeptide (α-hANP). Weakly immunoreactive cells were seen in both atrial and ventricular walls at 11 days post coitum (pc). After this stage, the immunoreactive cells became more intensely stained in both atrial and ventricular walls. The immunoreactivity during the prenatal period was stronger in the superficial cell layer beneath the endocardium, than in the deep cell layer of the atrial wall. The cells in the trabecular meshwork also had an apparent, but weak, immunoreactivity, which showed a greater intensity in the left ventricle than in the right one. It is suggested that these immunoreactive cells in the ventricle may differentiate, in situ, into the cells of the impulse-conducting system during the further development of the heart.
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  • 6
    ISSN: 1432-0878
    Keywords: Atrial natriuretic peptide (ANP) ; Chicken natriuretic peptide (chANP) ; Atrial-specific granule ; Sarcoplasmic reticulum ; Immunohistochemistry ; Domestic fowl (Aves, Phasianiformes)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An immunohistochemical study using antiserum raised against synthetic chicken natriuretic polypeptide was used to investigate the distribution of this peptide in the chicken heart. Immunoreactive cells, both in the atrial and ventricular walls, were identified by electron microscopy, and electron-dense granules in the atrial and ventricular cardiocytes were revealed to be storage sites of the peptide. The electron-dense material, thought to be the peptide, was found in the sarcoplasmic reticulum, and it is suggested that a secretory pathway of the peptide through the latter to extracellular space, may be present, in addition to an exocytotic one.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 293 (1998), S. 177-187 
    ISSN: 1432-0878
    Keywords: Key words Spermatozoon ; Acrosome ; Plasma membrane ; Antigenic molecules ; Maturation ; Modification ; Fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The mammalian spermatozoon is a terminally differentiated cell. Its surface is covered by a continuous plasma membrane that is divided into distinct domains in which functional molecules are distributed. The acrosome is an internal organelle located at the anterior head and contains hydrolytic enzymes. The anterior acrosome participates in the acrosome reaction, which is an indispensable event during fertilization. These surface domains and the acrosome are formed during spermiogenesis, during which associated molecules are transported and organized. Many of the molecules thus arranged are functionally immature but gradually become mature during epididymal maturation. Some of them are further altered and redistributed during the fertilization process and play various roles. Here, the sequential changes in the acrosome and plasma membrane during spermatozoan maturation are reviewed, particular attention being paid to molecules derived from the testis.
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  • 8
    ISSN: 1432-0878
    Keywords: Key words Acrosome ; Carbendazim ; mMN7 immunocytochemistry ; Spermatids ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Effects of a single, high dose of orally administered carbendazim (100 mg/kg) on acrosome formation in the early phases of spermiogenesis were examined by electron microscopy and immunocytochemistry up to day 7.5 post-treatment. No obvious abnormality of acrosome development was noted in the Golgi phase spermatids on day 1.5 post-treatment. On day 3, step 1 spermatids were seen in stage III seminiferous tubules. In stage V tubules at this post-treatment interval, direct connections between the trans-side saccules of the Golgi stacks and the outer acrosomic membranes were observed in step 5 spermatids. Similar direct connections between these two organelles were also observed in the advanced round spermatids in later stages at days 4.5 and 7.5. On day 4.5, step 1 and 3 spermatids were seen in stage V tubules. On day 7.5, round spermatids with various abnormalities of acrosome development were observed in stage VII tubules, in addition to the discontinuous and granular acrosomes reported previously. These features were not observed in testes of control animals. In the immunocytochemical analysis using an antibody mMN7 that recognizes a protein delivered from the Golgi apparatus to the acrosome, spermatids exposed to carbendazim showed various abnormal immunostaining patterns in the acrosomes. On the other hand, strong immunoreactivity was observed in the Golgi saccules connecting to the acrosomes. These results suggest that in testis treated with carbendazim acrosome development is impaired during the early phases of spermiogenesis, and material supply from the Golgi apparatus to the acrosome is perturbed, which is a possible cause of the abnormal development.
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  • 9
    ISSN: 1432-0878
    Keywords: Spermatozoa ; Filipin-sterol complex ; Freezefracture ; Epididymal maturation ; Hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of membrane filipin-sterol complexes (FSCs) was qualitatively surveyed on freeze-fracture replicas of spermatozoa from the male reproductive tract and ejaculates of golden hamster. In the head, the acrosomal plasma membrane showed the strongest filipin labeling on the principal segment, but it was absent in the “quilt-like pattern” areas. These latter were observed in both caput and corpus epididymal spermatozoa, but were absent in mature spermatozoa. The postacrosomal plasma membrane had few FSCs and both the outer and inner acrosomal membranes were always negative to filipin. The nuclear membrane of the principal segment was constantly filipinpositive. The nuclear membrane of the postacrosomal region had more FSCs than that of the principal segment, particularly in mature spermatozoa. Many linear, “rod-like FSCs” were observed on the postacrosomal nuclear membrane of mature spermatozoa, especially in the uterine spermatozoan samples. In the neck, the plasma membrane had only a few FSCs. The redundant nuclear membrane was slightly filipin-positive, while the membrane scroll of mature spermatozoa was heavily labeled. In the tail, the plasma membrane of both the middle and principal piece was moderately labeled.
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  • 10
    ISSN: 1432-0878
    Keywords: Heart ; Atrial-specific granules ; Atrial natriuretic polypeptide (ANP) ; Purkinje fiber ; Immunohistochemistry ; Impulse-conducting system ; Swine (Sus scrofa domestica)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of porcine ventricular tissue was studied by electron microscopy and immunocytochemical techniques. Electron-dense specific granules were found in both Purkinje fibers and transitional cells in the ventricular walls, and were positively stained by the immunogold staining method using an antiserum against atrial natriuretic polypeptide (ANP). This suggests that both the Purkinje fibers and transitional cells display the same specific granules as atrial cardiocytes containing ANP. These results demonstrate that Purkinje fibers and two types of transitional cells, in addition to the ordinary ventricular cardiocytes, can be identified in porcine ventricular wall tissue.
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