Hartmut Frenzel

Rat liver alterations after chronic treatment with hexachlorobenzene

Groups of female rats were treated orally with 0.5, 2.0, 8.0, and 32 mg/kg hexachlorobenzene twice a week for 203 days. The liver content of hexachlorobenzene was found to be dose-dependent. In the animals treated with the highest dose the concentration was 273 μg/g hexachlorobenzene. In the fresh and fixed hepatic tissue of the treated animals pink fluorescence was observed. Electron microscopy revealed a dose dependent enlargement of all hepatocytes due to proliferation of the SER in the centrolobular area or to increased glycogen deposits (β- or α-particles) and SER in the intermediary and periportal area. Numerous porphyrin deposits and siderosomes, intimate disorganisation and moderate dislocation of the RER and a moderate enlargement of bizarre-shaped mitochondria were recognized. The relationship between porphyrin crystals and mitochondria on the one hand and between SER and glycogen deposits on the other is discussed.

Der Einfluß des Perfusionsdruckes bei der Perfusionsfixation auf die Feinstruktur der Lebersinusoide. Transmissions- und rasterelektronenmikroskopische Untersuchung

The fixation of rat liver by perfusion with glutaraldehyde with different pressures has been investigated. For this study adult male albino rats were used. Rat livers were fixed by perfusion through the abdominal aorta according to the method of FORSSMANN et al. (1967). Perfusion pressures varied from 30 to 210 mmHg. A continuous complete endothelial lining of liver sinusoids could be visualized with TEM and SEM after fixation with perfusion pressures lower than 100 mmHg. Three different regions could be noticed in the endothelial cell: 1. prominent nucleous region, 2. compact cytoplasmic processions containing mitochondria and ergastoplasma, 3. delicate fenestrated cytoplasmic areals. As a rule the fenestrations were localized in groups, s.c. sieve plates. After perfusion fixation with pressures above 100 mmHg the endothelial lining of liver sinusoids appeared similar to a wide-meshed net. The sieve plates were destroyed, and numerous defects could be found in the endothelial cells. Hepatocytes showed vacuoles which seem to be due to invagination of the cellular membrane. For the development of artifacts even with physiological perfusion pressures in the aorta (110 mmHg), the content of procaine in the rinsing solution is responsible. Eliminating the function of arteriols leads to unphysiological pressure effects in the sinusoids.SummaryThe fixation of rat liver by perfusion with glutaraldehyde with different pressures has been investigated. For this study adult male albino rats were used. Rat livers were fixed by perfusion through the abdominal aorta according to the method of FORSSMANNet al. (1967). Perfusion pressures varied from 30 to 210 mmHg.A continuous complete endothelial lining of liver sinusoids could be visualized with TEM and SEM after fixation with perfusion pressures lower than 100 mmHg. Three different regions could be noticed in the endothelial cell: 1. prominent nucleous region, 2. compact cytoplasmic processions containing mitochondria and ergastoplasma, 3. delicate fenestrated cytoplasmic areals. As a rule the fenestrations were localized in groups, s.c. sieve plates.After perfusion fixation with pressures above 100 mmHg the endothelial lining of liver sinusoids appeared similar to a wide-meshed net. The sieve plates were destroyed, and numerous defects could be found in the endothelial cells. Hepatocytes showed vacuoles which seem to be due to invagination of the cellular membrane.For the development of artifacts even with physiological perfusion pressures in the aorta (110 mmHg), the content of procaine in the rinsing solution is responsible. Eliminating the function of arteriols leads to unphysiological pressure effects in the sinusoids.ZusammenfassungAusgewachsene männliche Albinoratten wurden modifiziert nach FORSSMANN u. Mb. (1967) über die Aorta abdominalis retrograd mit Drucken von 30, 50, 70, 110 und 210 mmHg perfusionsfixiert.Bei Perfusionsdrucken unter 100 mmHg stellte sich im TEM und REM eine vollständige lückenlose endotheliale Zellauskleidung der Lebersinusoide dar. An den Endothelzellen ließen sich drei Regionen voneinander abgrenzen: 1. leicht prominente Kernregionen, 2. kompaktere Zytoplasmafortsätze mit Mitochondrien und Ergastoplasma, 3. sehr dünne, vielfach fenestrierte Zytoplasmaanteile. Die Fenestrationen lagen in der Regel in Gruppen - sog. Siebplatten - zusammen.Bei Perfusionsdrucken über 100 mmHg glich die endotheliale Zellauskleidung der Lebersinusoide einem groben Netz. Die Siebplatten waren zerstört, an ihrer Stelle fanden sich z.T. konfluierende Defekte in den Endothelzellen. In zahlreichen Leberepithelzellen waren durch Invagination der Zellmembran Vakuolen entstanden.Die Untersuchungen zeigen, daß bei der Perfusionsfixation bereits bei physiologischen Perfusionsdrucken in der Aorta (110 mmHg) ausgeprägte Artefakte in den Lebersinusoiden entstehen. Durch den Procain-Zusatz zur Spüllösung wird die Arteriolenfunktion weitgehend ausgeschaltet, so daß in den terminalen Gefäßabschnitten pathologische Drucke auftreten.

Time sequence and site of fluid accumulation in experimental neurogenic pulmonary edema.

SummaryThe initial phase of pulmonary edema development following intracranial pressure elevation was studied by means of transmission electron microscopy. Using perfusion fixation and application of a blood tracer (HRP horseradish peroxidase) the time sequence and site of fluid leakage out of pulmonary vessels was demonstrated: - passage of edema fluid through intercellular clefts of alveolar capillary endothelium - edema accumulation in alveolar interstitial tissue - draining of edema fluid from the alveolar septum to the interstitium of terminal bronchioli and to lymphatic vessels. An early interepithelial fluid leakage out of the alveolar wall remains questionable.

Die Lebersinusoide der Ratte nach fraktionierter lokaler Telekobalt-Bestrahlung

Changes in liver sinusoids following fractionated irradiation were studied by use of TEM and SEM. Rats received telecobalt-irradiation of their liver regions in daily doses of 500 r for 9 days, a total dose of 4500 r. One day after the end of the irradiation series the fine structure of hepatocytes was almost intact. In SEM the liver sinusoids contained numerous corpuscles, which in TEM were recognized as cellular blebs separated from endothelial cells. 8 days after irradiation small foci of necrotic hepatocytes could be visualized. Instead of complexes of small fenestrations (sieve plates) the endothelial cells contained striking round or oval holes in their tenuous processes. After 120 days small groups of hepatocytes with alterated fine structure of their organelles and some necrotic parenchyma cells were still present. Away from these focal necroses the endothelial cells now resembled sinusoidal endothelium in control animals. Fat-storing cells appeared to have multiplied and were enlarged. There was distinct fibrosis only in perisinusoidal spaces. The formation and discharge of electron lucent blebs is discussed as a mechanism compensating for an enhanced uptake of fluid into irradiation injured endothelial cells. In order to form holes in the tenuous processes of endothelial cells a disordered synthetic pattern and the shearing forces of the circulating blood are thought to be necessary. Repair of these intracellular holes may be possible. In rats irradiation induced lesions of the small intrahepatic vessels can be excluded as a cause of the late changes in liver parenchyma cells. Mit dem Transmissions- und Rasterelektronenmikroskop wurden die Früh- und SpÄtverÄnderungen der Lebersinusoide bestrahlter Ratten untersucht. Die Tiere erhielten über 9 Tage eine Telekobalt-Bestrahlung von 4500 r in tÄglichen Dosen von 500 r auf die Leberregion. 1 Tag nach Abschlu\ der Bestrahlungsserie war die Feinstruktur der Hepatocyten weitgehend normal. Die Sinusendothelzellen wiesen zahlreiche blasige Zellabschnürungen auf, die im Rasterelektronenmikroskop als unterschiedlich gro\e Korpuskel imponierten. 8 Tage nach Bestrahlung kamen vereinzelt kleine Gruppen nekrotischer Hepatocyten vor. An den Endothelzellen fielen gro\e runde oder ovale Löcher im Bereich der fenestrierten Zellabschnitte auf. 120 Tage nach Bestrahlung waren noch immer kleine Gruppen von Hepatocyten mit feinstrukturellen VerÄnderungen ihrer Zellorganellen und vereinzelt auch Gruppennekrosen nachzuweisen. Abgesehen von den kleinen Nekroseherden wurden die Sinusoide wieder von Endothelzellen mit intakten Fenestrationen lückenlos ausgekleidet. Die Fettspeicherungszellen erschienen vergrö\ert und vermehrt. Eine nennenswerte Fibrosierung war in den Sinusoiden nicht nachweisbar. Die Abschnürung von elektronenoptisch leeren, vermutlich wasserreichen Blasen wird als möglicher Ausgleich einer gesteigerten Flüssigkeitsaufnahme strahlengeschÄdigter Endothelzellen diskutiert. Für die Entstehung von Löchern in den dünnen EndothelzellauslÄufern wird den ScherkrÄften des Blutstromes bei gestörtem Strukturerhaltungs-Stoffwechsel der Zelle eine Bedeutung beigemessen. Eine Reparation dieser Zelldefekte scheint möglich. Für die Ratte kann eine Strahlenvaskulopathie der kleinen intrahepatischen BlutgefÄ\e als Ursache von SpÄtschÄden des Leberparenchyms nach Bestrahlung weitgehend ausgeschlossen werden.Changes in liver sinusoids following fractionated irradiation were studied by use of TEM and SEM. Rats received telecobalt-irradiation of their liver regions in daily doses of 500 r for 9 days, a total dose of 4500 r. One day after the end of the irradiation series the fine structure of hepatocytes was almost intact. In SEM the liver sinusoids contained numerous corpuscles, which in TEM were recognized as cellular blebs separated from endothelial cells. 8 days after irradiation small foci of necrotic hepatocytes could be visualized. Instead of complexes of small fenestrations (sieve plates) the endothelial cells contained striking round or oval holes in their tenuous processes. After 120 days small groups of hepatocytes with alterated fine structure of their organelles and some necrotic parenchyma cells were still present. Away from these focal necroses the endothelial cells now resembled sinusoidal endothelium in control animals. Fat-storing cells appeared to have multiplied and were enlarged. There was distinct fibrosis only in perisinusoidal spaces. The formation and discharge of electron lucent blebs is discussed as a mechanism compensating for an enhanced uptake of fluid into irradiation injured endothelial cells. In order to form holes in the tenuos processes of endothelial cells a disordered synthetic pattern and the shearing forces of the circulating blood are thought to be necessary. Repair of these intracellular holes may be possible. In rats irradiation induced lesions of the small intrahepatic vessels can be excluded as a cause of the late changes in liver parenchyma cells.

Scanning electron microscopy of the distal nephron and calyx of the human kidney.

SummarySurface fine structures of human distal nephron, papilla and calyx were studied by use of SEM. Tissue preservation was carried out by perfusion fixation and critical point drying. The various surface features of epithelial cells were visualized in the lower urinary tract.

Über den Einfluß der Hypoxie auf die Sinusendothelzellen der Rattenleber

SummaryFine structural alterations of liver sinusoids in young and adult albino rats breathing 6% oxygen in nitrogen at normal atmospheric pressure for periods from 3 to 30 h were described by use of TEM and SEM. After short—term hypoxia the fenestrated areas of endothelial cells were partially destroyed. After long—term hypoxia wide gaps could be visualized in the endothelium, too. In the liver specimens of all hypoxic animals electron lucent membrane bounded blebs arose from the endothelial lining. Cytoplasmic protrusions of hepatocytes bulged into the sinusoidal lumen. In the space of Disse and the sinusoidal lumen bleblike corpuscles and parts of cytoplasmic membrane being discharged from liver cell vacuoles could be observed. The fine structure of liver sinusoids in hypoxia was very similar in young and adult albino rats.The findings suggest a discharge of metabolites and cellular components from endothelial cells and hepatocytes in a state of energetic insufficiency by forming cellular blebs and protrusions. It was supposed, that the combined effects of hypoxia and shearing of circulating blood were responsible for the development of holes and gaps in the endothelial lining.ZusammenfassungMit dem TEM und REM wurden die feinstrukturellen Veränderungen der Lebersinusoide von jungen und ausgewachsenen Albinoratten nach 3, 6 und 30stündiger respiratorischer Hypoxie untersucht.Nach 3stündiger Hypoxie fanden sich Defekte in den fenestrierten Anteilen der Endo-thelzellen, nach 6 und 30stündiger Hypoxie waren zusätzlich größere Lücken im Endothel-zellverband nachweisbar. In allen Versuchsgruppen wurden blasige Abschnürungen an den Endothelzellen beobachtet. Vereinzelt fanden sich plumpe Cytoplasmaprotrusionen der Leber-parenchymzellen in die Sinuslichtung, häufig wurden aus Leberzellvakuolen blasige Gebilde und Membrananteile in die Sinusoide abgegeben. Das morphologische Bild der Lebersinusoide bei Hypoxie war bei jungen und ausgewachsenen Ratten weitgehend gleich.Die Befunde lassen vermuten, daß die energetisch insuffizienten Endothelzellen und Hepatocyten Stoffwechselprodukte und Zellmaterial in Form von blasigen Abschnürungen abgeben. Als Ursache der Defekte in den Endothelzellen wird das Zusammenwirken von Sauerstoffmangel und Strömungskräften des Blutes angenommen.