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  • 1
    Electronic Resource
    Electronic Resource
    Renin immunohistochemistry in the mesonephros and metanephros of the pig embryo (1984)
    Springer
    Histochemistry and cell biology 81 (1984), S. 385-390 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The occurrence and distribution of renin was investigated in meso- and metanephric kidneys of pig embryos in various gestational stages. The immunohistochemical peroxidase-antiperoxidase-method (PAP) was used on paraffin sections after application of an antiserum against mouse renin which cross reacts with pig renin. Renin immunoreactivity was already found in the mesonephros of 21 day pig embryos (crown-rump(CR)-length 12 mm) with the strongest reaction in the media of the juxtaglomerular afferent arteriole. Efferent vessels, mesonephric arteries, and the aortic wall also contained scattered renin-positive cells. In the definitive kidney, renin was not detected prior to the 25 mm CR-length-stage. In 45 mm embryos, immunocytochemical staining was observed not only in the media of kidney arteries and arterioles, but also in proximal tubules after pinocytic absorption of filtered renin. TEM-studies revealed that the media of both the mesonephric and the developing metanephric arteries and arterioles contains epithelioid cells whose ultrastructure is very similar to that of renin-producing cells in the adult organ. The observed distribution of renin-producing cells along the entire renal arterial tree points to the possibility that the major function of the renin-angiotensin system in the fetal animal is to participate in the stabilization of renal perfusion pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00514334
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  • 2
    Electronic Resource
    Electronic Resource
    The pig yolk sac II (1980)
    Springer
    Histochemistry and cell biology 68 (1980), S. 147-158 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Since previous morphological studies have revealed abundant rough endoplasmic reticulum in the yolk sac endoderm, pig yolk sac explants from 30 day old embryos were incubated for 3–12 h with [3H]-l-leucine in order to study their protein biosynthesis. They were fractionated into a 12,000×g-pellet, 105,000×g-pellet, and supernatant. Newly synthesized proteins in these tissue fractions, and proteins discharged into the culture medium, were analysed with the aid of scintillation technique and identified by column chromatography, SDS-polyacrylamide gel electrophoresis with urea, isoelectrofocusing, and 2D-electrophoresis. Most of the radioactivity incorporated into the tissue fractions was regained from the coarse pellet and was located in the molecular weight region between 70,000 and 45,000 daltons, indicating that most of the newly synthesized proteins are membrane bound and include albumin. Albumin, an acid protein of a MW around 80,000 daltons, and many neutral and basic peptides were present in the culture medium. The yolk sac endodermal cells of the pig synthesize less proteins than those of the cat, although the pig cells display much larger amounts of endoplasmic reticulum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00489510
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  • 3
    Electronic Resource
    Electronic Resource
    The pig yolk sac I (1980)
    Springer
    Histochemistry and cell biology 68 (1980), S. 133-146 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Yolk sacs from pig embryos ranging between 18 mm and 55 mm in length were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and histochemistry. The organ was no longer present in embryos of 70 mm length. The endoderm proliferates in embryos of about 20 mm length with gland-like endodermal cell columns and finally becomes stratified, representing over 90% of the yolk sac mass. The endodermal cells show a high activity of oxidoreductases and lysosomal enzymes; their luminal surface bears few absorptive specializations. The mesothelium is inert, as judged from its surface ultrastructure, organelle composition and enzyme content. TEM reveals the endodermal cells to be polarized even in stratified areas. They resemble liver parenchymal cells with respect to their basal villi, which are exposed to capillaries with discontinuous or fenestrated endothelium. Giant mitochondria with crystalline inclusions in the mature endodermal cytoplasm are outnumbered by large stacks of the rough ER, which can amount to 60% of the cytoplasm. This conspicuous RER is suspected to be the production site of serum proteins which are discharged into the vascular bed. Close to the time of the organ's regression, an unusual storage of material in terminal buds of the ER was found. Intercellular canaliculi and the endocytic apparatus of the endoderm are thought to serve regression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00489509
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  • 4
    Electronic Resource
    Electronic Resource
    Elektronenmikroskopischer Nachweis der Adenosintriphosphataseaktivität am Amnion-, Nabelstrang-und Hautepithel beim Schaffetus (1971)
    Springer
    Histochemistry and cell biology 27 (1971), S. 310-319 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Nach Inkubation formaldehydfixierter, nicht gefrorener Amnion-, Nabelstrang- und Hautepithelblöckchen von 10 Schaffeten zwischen 3 und 42 cm SSL im Wachstein-Meisel-Medium konnte ATPase-Aktivität beobachtet werden. Das Reaktionsprodukt lag an der äußeren Plasmalemmlamelle der Zellseitenflächen, beim Amnion-und Nabelstrangepithel auch am apikalen Plasmalemm. Keine Aktivität zeigten das Plasmalemm an der Basalmembran, das apikale Plasmalemm der Peridermzellen, Schlußleisten, Desmosomen und mikropinozytotische Membranvesikulationen. Die Reaktion an der Epidermis war bedeutend schwächer als die am Amnion- und Nabelstrangepithel. Die funktionelle Bedeutung der nachgewiesenen Enzymaktivität an den untersuchten Epithelien wird diskutiert.
    Notes: Summary ATPase-activity could be demonstrated in unfrozen, formaldehyde-fixed tissue blocks of amniotic epithelium, cord epithelium and epidermis of 10 fetal sheep ranging from 3 to 42 cm CRL following incubation in the Wachstein-Meisel medium. Reaction product deposition was associated with the extracellular side of the plasma membrane of the lateral cell aspects, and in amniotic and cord epithelium with microvilli of the apical surface. No deposits were to be found along the basal lamina, the apical surface of the peridermal cells, terminal bars, desmosomes, and pinozytotic vesicles adherent to the plasma membrane. The fetal epidermis showed only few deposits of lead phosphate. The possible functional significance of the demonstrated enzyme activity is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305333
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of serum proteins by the posthaematopoietic feline yolk sac (1980)
    Springer
    Histochemistry and cell biology 67 (1980), S. 155-167 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The feline yolk sac persists even after the end of its haematopoietic phase with prominent ER-cisternae in the endoderm suggesting biosynthetic capacity. Therefore, yolk sac explants from the 54th day and 57th day were incubated with [3H]-l-leucine in order to study its protein biosynthesis. Newly synthesized proteins were discovered in sliced SDS-polyacrylamide gels by the use of scintillation technique and identified by molecular weight determination and isoelectrofocusing, also using stained electropherograms of unlabeled tissue, serum, and marker proteins. The highest radioactive incorporations were found in 69,000–70,000 dalton proteins and interpreted as serum albumin and α-fetoprotein. The autoradiography revealed that the cytoplasm of the endoderm is the site of the most active biosynthesis of proteins which were obviously stored in the ER-cisternae for some time. The yolk sac fluid proteins are almost exclusively serum proteins, although in a very low concentration. We regard a large-scale formation of serum proteins in the yolk sac endoderm as the cause of this organ's very late regression in the cat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493233
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  • 6
    Electronic Resource
    Electronic Resource
    Zur Theorie der Relaxationseffekte an Elektronenlawinen (1959)
    Springer
    Naturwissenschaften 46 (1959), S. 199-199 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00632566
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  • 7
    Electronic Resource
    Electronic Resource
    Elektronennachlieferung in den Gasen N2, H2 und O2 bei niedrigen Drucken (pd ≈ 50 Torr·cm) (1958)
    Springer
    The European physical journal 150 (1958), S. 299-310 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Zusammenfassung Durch oszillographische Beobachtung von Lawinen-Impulsketten werden Art und Ausbeute des Nachlieferungsmechanismus (γ-Effekt) in N2, O2 und H2 beipd ≈ 50 Torr·cm ermittelt. In Stickstoff dominiert die Wirkung der positiven Ionen,γ i = 1,5·10−6 (an oxydierter Cu-Kathode) bisγ i 〉 10−3 (an durch Ausheizen in H2 reduzierter Cu-Kathode). Dabei treten Generationsabstände auf, die größer als die Ionenlaufzeit sind. In Wasserstoff trägt der Photoeffekt den Hauptanteil der Nachlieferung,γ p =5·10−5 (an oxydierter Cu-Kathode) bisγ p = 1·10−6 (an reduzierter Cu-Kathode),γ i ≈10−7. Sauerstoff zeigt an frisch reduzierter Cu-Kathode einγ i ≈10−7, was innerhalb einer Stunde auf Werte 〈 10−10 zurückgeht. Im übrigen erfolgt die Nachlieferung durch Photoeffekt,γ p = 10−6 (an oxydierter Cu-Kathode). Mit oxydiertem Wolfram als Kathodenmaterial konnte dieγ-Ausbeute in Sauerstoff auf einige 10−9 herabgedrückt werden, so daß die kritische Verstärkung für den Kanaldurchschlag erreicht wurde.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322323
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  • 8
    Electronic Resource
    Electronic Resource
    Release of a virus coded glycoprotein from herpes simplex virus type 1 infected cells (1988)
    Springer
    Molecular biology reports 13 (1988), S. 29-33 
    Details
    ISSN: 1573-4978
    Keywords: HSV-1 infected cells ; monensin ; protein excretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract HEp-2 cells, which were infected with HSV-1, excrete besides other proteins a soluble glycoprotein (Mr 125000–130000) related to the virus protein gC. The excretion of the glycoprotein and the production of extracellular virus particles is reduced to a similar extent when the cells were treated with monensin. Possible consequences of the excretion of soluble viral proteins to a modulation of the immune response are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805636
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  • 9
    Electronic Resource
    Electronic Resource
    Die Ultrastruktur des Epithels des Wolffschen Ganges und des Ductus deferens beim Schafembryo (1971)
    Springer
    Cell & tissue research 113 (1971), S. 230-248 
    Details
    ISSN: 1432-0878
    Keywords: Wolffian duct ; Vas deferens ; Sheep ; Ultrastructural differentiation of the epithelium ; Functional aspects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Epithelzellen der Wolffschen Gänge bzw. der Samenleiter von 28 Schafembryonen der Größe von 1,1–45 cm Scheitel-Steiß-Länge (SSL) wurden elektronenmikroskopisch untersucht. Der Golgiapparat von Embryonen in der Phase der aktiven Urnierensekretion zeichnet sich durch Zisternen mit kondensiertem Inhalt aus, von denen sich kleine coated vesicles abschnüren. Bei Feten mit inaktiver Urniere wurden keine Zisternen mit kondensiertem Inhalt beobachtet. Die Abschnürung kiemer coated vesicles vom Golgiapparat tritt jedoch in allen untersuchten Altersstadien auf. Eine zweite Population großer coated vesicles schnürt sich vom apikalen, basalen und interzellulären Plasmalemm ab, besonders häufig beim fast geburtsreifen Fetus. Die Vereinigung von Golgivesikeln mit einem Inhalt von mittlerer Elektronendichte mit multivesikulären Körpern kann in allen untersuchten Stadien festgestellt werden. Glykogen findet sich bereits bei 1,1 cm SSL in Lagern; ab ca. 20 cm SSL ist eine erhebliche Glykogenvermehrung zu beobachten. Stereozilien und glattes endoplasmatisches Retikulum treten erst ab 45 cm SSL auf.
    Notes: Summary The ultrastructure of the epithelium of the Wolffian duct and of the vas deferens of fetal sheep ranging from 1,1 to 45 cm CRL has been studied. The Golgi apparatus of specimens possessing an actively secreting mesonephros shows condensation of the contents of the cisternae with budding of small coated vesicles. In the fetuses possessing inactive mesonephros no condensation of the contents of Golgi cisternae is to be observed, but the budding of small coated vesicles continues. A second population of large coated vesicles originating by invagination of the plasma membrane occurs on the periphery of the epithelium cells, namely in the apical cell poles of the near term fetuses. The convergence and subsequent fusion of Golgi vesicles of medium electron density is already found in patches in the 1,1 cm CRL fetus; it increases in abundance in specimens of more than 20 cm CRL. Stereocilia and agranular endoplasmatic reticulum appear in full-term sheep fetuses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00339418
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  • 10
    Electronic Resource
    Electronic Resource
    The mature mesonephric nephron of the rabbit embryo (1981)
    Springer
    Cell & tissue research 221 (1981), S. 431-442 
    Details
    ISSN: 1432-0878
    Keywords: Kidney (rabbit) ; Development ; Mesonephric nephron ; Freeze-fracture electron microscopy ; Intercellular junctions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In freeze-fracture replicas of the entire cross-fractured mesonephros of 18 day rabbit embryos the basolateral and luminal cell faces of the different nephron segments were studied and compared with their metanephric counterparts. In the proximal tubule, the shallow zonula occludens exhibited only 1–2 strands and resembled the corresponding metanephric zonula, a very “leaky” type, which was found with a considerable paracellular flow component in sites of isotonic reabsorption. Gap junctions were restricted to the proximal tubule and were seen more frequently in its terminal segment. The distal tubule harboured two types of tight junctions. The most common type, a band of 5–8 closely parallel strands, matched the zonula occludens of the metanephric straight distal tubule. The observed particle density of the basolateral membrane (2,500±328/μm2) was less than that of the proximal tubule (2,642±306). In addition, the collecting tubule exhibited a zonula occludens of the “tight” variety similar to that which occurred in the metanephric collecting duct. Rod-shaped particles of the luminal membrane were mainly concentrated in some of the intercalated cells but also had developed on principal cells, and occasionally, in the distal tubule. The Wolffian duct, with a deep “tight” zonula occludens, had an obviously rather inactive epithelium with no conspicuous transport-linked membrane specializations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216746
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