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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 151 (1977), S. 109-118 
    ISSN: 1432-0568
    Keywords: Iris ; Mesenchymal cells ; Chicken embryo ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The iris anlage of 3–10 day old chicken embryos was studied by both light and electron microscopy. Serial semithin sections showed that some of the mesenchymal cells overlying the eye cup moved into the primitive eye cavity by the 3rd day of incubation. On the 4th day some of these cells came into close contact with the basement membrane of the dorsal iris epithelium. The bases of the epithelial cells were flat at this stage. Towards the 10th day they formed cytoplasmic processes which did not penetrate the basement membrane. Fine mesenchymal cytoplasmic processes and a large number of extracellular fibrils developed in the epithelial-mesenchymal interface. The fine mesenchymal processes came into close contact with the basement membrane of the posterior iris epithelium but did not penetrate it. Collagen-like material was observed within the cisternae of the rough ER of the mesenchymal cells at certain stages of development. Both, the mesenchymal cells and the collagen fibrils adjacent to the posterior iris layer disappeared by the 10th day when the entire iris epithelium was completely pigmented. The possible origin of the collagen fibrils and the differentiation of the posterior iris epithelium are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 147 (1975), S. 177-187 
    ISSN: 1432-0568
    Keywords: Iris ; Melanogenesis ; Chicken embryo ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The iris anlage of 2–10 and 15 days old chicken embryos were studied histochemically, and by both light and electron microscopy. Light microscopic serial sections showed that pigmentation began at the outer layer of the posterior eye pole and progressed from there forwards to the optic cup margin. The entire outer layer of the optic cup as well as the pupillary margin were completely pigmented by the 4th day of incubation. By the 10th day the posterior iris epithelium was totally pigmented. Electron microscopical studies showed that the first premelanosomes appeared at about the 3rd day of incubation in the anterior iris anlage with the exception of the pupillary margin. It could be shown that melanogenesis progressed through the following steps: premelanosomes, followed by tyrosinase activity in a Golgi-associated system of smooth endoplasmic reticulum (GERL) and small vesicles and finally differentiation of the melanosomes. The possible origin of the premelanosomes and the formation of melanin are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Anatomia, histologia, embryologia 24 (1995), S. 0 
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A panel of monoclonal antibodies to the growth hormone (GH) receptor/binding protein was used to demonstrate the existence and detail the expression of GH receptors in ductal and alveolar epithelial cells from rat and rabbit mammary glands by immunohistochemistry. Intense immunoreactivity was present in membrane, cytoplasm and some nuclei of epithelial cells during proliferation and lactation. Receptor expression decreased during weaning and was absent or weak in regressive mammary glands. Immunoreactivity was weak in ductal epithelial cells from virgin adult animals. Pronounced expression of GH receptor/binding protein was observed with two monoclonal antibodies and lesser reactivity was seen with others, paralleling their affinities for the receptor. The cytoplasmic presence of this putatively plasma membrane located GH receptor is accounted for by the existence of a soluble form on the GH receptor, namely the growth hormone binding protein derived from the membrane receptor by cleavage. Primary localization of the receptor in proliferating and lactating epithelial cells suggests that the rat and rabbit mammary gland is a GH target tissue. This finding is in contradiction to both classical GH action and the somatomedin hypothesis and challenges the widely held view that GH has no direct influence on mammary growth and function.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 240 (1984), S. 277-285 
    ISSN: 1434-4726
    Keywords: Vocal cord ; Glands ; Microridges ; Light microscopy ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The human vocal cord was studied by light and electron microscopy. Serial histological sections showed that a great number of mixed glands with mucous and serous acini were localized in the submucosa. Their ducts leave the deep surface of the gland and some open at the vocal cord surface near the free edge. The margin of the vocal cord does not have glandular ducts; however, its stratified squamous epithelium is furnished with microvilli and microridges of various patterns. The observed location of the glandular ducts is described and the possible function of the microridges in relation to distribution and retention of mucous on the vocal cord is discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 28 (1972), S. 74-76 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A hitherto unidentified endocrine ‘glandula perioesophagealis’ inPolyxenus lagurus is described. Its cells are typical podocytes. Between the pedicells there are many intercellulary spaces. In animals close to molting, the gland cells are activated.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0533
    Keywords: Key words Ammonia ; Glia ; Retina ; Morphometry ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract More than 80 years ago, Alzheimer described changes in the brains of patients who had suffered hepatic failure. Astrocytes are primarily affected; their nuclei become swollen, their intermediate filament protein composition is altered and their cytoplasm becomes vacuolated. Cells with these features are called Alzheimer type II astrocytes and these changes have been attributed to the toxic effects of elevated ammonia levels. The present study investigates whether the dominant glia of another part of the central nervous system, the Müller cells of the retina, undergo similar changes. Retinae of patients who had died with symptoms of hepatic failure were processed for histology, histochemistry, and immunocytochemistry. Cell nuclei were measured from brain astrocytes (insula cortex), Müller cells, and retinal bipolar neurons. Hepatic failure resulted in the enlargement of nuclei in astrocytes and Müller cells, and the enhanced expression in Müller cells of glial fibrillary acidic protein, cathepsin D, and the β-subunit of prolyl 4-hydroxylase (glial-p55). In some retinae, signs of gliosis were also observed. We conclude that increased levels of serum ammonia resulting from hepatic insufficiency cause changes in Müller cells that are similar to those seen in brain astrocytes. We term this condition hepatic retinopathy.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0533
    Keywords: Ammonia ; Glia ; Retina ; Morphometry ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract More than 80 years ago, Alzheimer described changes in the brains of patients who had suffered hepatic failure. Astrocytes are primarily affected; their nuclei become swollen, their intermediate filament protein composition is altered and their cytoplasm becomes vacuolated. Cells with these features are called Alzheimer type II astrocytes and these changes have been attributed to the toxic effects of elevated ammonia levels. The present study investigates whether the dominant glia of another part of the central nervous system, the Müller cells of the retina, undergo similar changes. Retinae of patients who had died with symptoms of hepatic failure were processed for histology, histochemistry, and immunocytochemistry. Cell nuclei were measured from brain astrocytes (insula cortex), Müller cells, and retinal bipolar neurons. Hepatic failure resulted in the enlargement of nuclei in astrocytes and Müller cells, and the enhanced expression in Müller cells of glial fibrillary acidic protein, cathepsin D, and the β-subunit of prolyl 4-hydroxylase (glial-p55). In some retinae, signs of gliosis were also observed. We conclude that increased levels of serum ammonia resulting from hepatic insufficiency cause changes in Müller cells that are similar to those seen in brain astrocytes. We term this condition hepatic retinopathy.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 225 (1987), S. 226-234 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the rat, continous exposure to so-called “cold light” of 800 lux leads to a nearly complete loss of retinal photoreceptors, which occurs within 4 weeks. This process is followed by vascularization of the retinal pigment epithelium (RPE). The origin, extent, and expansion of such proliferations within 6 months after the onset of irradiation were evaluated by means of light microscopy, transmission electron microscopy, scanning electron microscopy, corrosion cast preparation, india ink injection, and trypsin digest preparation. The vessels within the RPE were found to be fenestrated and to form a network with the vessels of the neurosensory retina. Invasion of Bruch's membrane and formation of chorioretinal anastomoses were not observed. The occurrence of vessels within the RPE coincided with a massive regression of capillaries in the neurosensory retina.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 24 (1995), S. 507-517 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have carried out a light microscopical study of Müller cells in the retinae of rats with inherited retinal dystrophy (Royal College of Surgeons rats). Isolated retinae of both control and Royal College of Surgeons rats were exposed to a Procion Yellow solution which is taken up selectively into Müller cells. The shape of the cells was then studied by confocal microscopy. Enzymatically isolated Müller cells were studied immunocytochemically with antibodies against glial fibrillary acidic protein, cathepsin D, β-amyloid precursor protein, bcl-2 protooncogene product, and glutamine synthetase. Müller cells from RCS retinae were shorter than those from control retinae, and showed a coarse hypertrophy of their distal (sclerad) processes. In Müller cells isolated from the retinae of Royal College of Surgeon's rats, the expression of glial fibrilliary acidic protein, cathepsin D, β-amyloid precursor protein and bcl-2 protooncogene product was increased, and the expression of glutamine synthetase was reduced. Obviously, loss of neighbouring neurons leads to major alterations of both the shape and metabolism of Müller cells. The expression of enzymes that serve functional glio-neuronal interactions, such as glutamine synthetase, seems to be down-regulated, whereas proteins involved in cell reconstruction (cathepsin D), cell repair (possibly β-amyloid precursor protein), and protection against apoptotic cell death (bcl-2 protooncogene product), are up-regulated, together with the ‘pathological marker’ glial fibrilliary acidic protein.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 132 (1972), S. 273-285 
    ISSN: 1432-0878
    Keywords: Diplopoda ; Organ of Gabe ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Das Gabesche Organ von Schizophyllum sabulosum ist paarig und liegt im seitlichen Clypeolabrum. Es wird von Axonen des Nervus labri medialis erreicht, der vorher Seitenzweige abgegeben hat. 2. Die Axone gehören neurosekretorischen Zellen des Protocerebrum an und enthalten Neurosekret. Die Elementargranula sind recht gleichmäßig ellipsoid, der große Durchmesser beträgt ca. 1200 Å. Die Axone enden im Organ und stellen dessen extrinsische Komponente dar. 3. Außerdem gibt es zwei intrinsische Zelltypen: 1) Drüsenparenchymzellen mit axonartigen Fortsätzen und 2) gliaartige Zellen. Die Parenchymzellen bilden Sekret in Form opaker Vakuolen, die deutlich größer als die Neurosekretgranula sind. Auffällig ist das überwiegend vesikuläre endoplasmatische Reticulum. Die Mitochondrien liegen in der Nähe von myelinähnlichen Körpern; ihre Außenmembran ist stellenweise vakuolig vorgewölbt. Die axonartigen Fortsätze enthalten viele längsorientierte Mikrotubuli. 4. Die langen Fortsätze der gliaartigen Zellen umhüllen die Parenchymzellen und die extrinsischen Axone meist in mehreren Schichten. Es gibt aber auch Bereiche, in denen vor allem die Fortsätze der Parenchymzellen und die extrinsischen Axone nackt sind. 5. Das Organ ist gegen das umgebende Hämocoel von einer dicken, lamellierten Stromahülle abgegrenzt. Auch Interzellularräume sind mit Stroma gefüllt. 6. Das Organ wird mit der Cerebraldrüse einiger Chilopoden und gewissen endokrinen Organen anderer Diplopoden und Insekten verglichen.
    Notes: Summary 1. The paired organ of Gabe of Schizophyllum sabulosum is situated in the lateral clypeolabrum. It is innervated by axons of the medial labral nerve, which divides in several branches before reaching the organ. 2. Axons extend from neurosecretory cells of the protocerebrum and contain neurosecretory droplets, which are almost ellipsoid and about 1,200 Å in diameter. The axons terminate in the organ and constitute its extrinsic elements. 3. In addition, there are two types of intrinsic cells: (1) parenchyma cells with axon-like processes and (2) glia-like cells. The parenchyma cells produce secretory material in the form of opaque vacuoles, which are clearly larger than the neurosecretory granules. The preponderantly vesicular endoplasmic reticulum is conspicuous. Also characteristic are the mitochondria, whose superficial membranes are expanded locally, and which lie in the near vicinity of myeline-like bodies. The axon-like processes contain many microtubuli oriented in longitudinal direction. 4. The slender processes of the glia-like cells envelop both parenchyma cells and extrinsic axons usually in several layers; but there are also regions in which the processes of the parenchyma cells and, above all, the extrinsic axons are naked. 5. The organ is delimited from the surrounding hemocoele by a thick laminated stroma. Intercellular spaces are also filled with stroma. 6. The organ is compared with the cerebral gland of some chilopods and with certain endocrine organs of other diplopods and insects.
    Type of Medium: Electronic Resource
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