Showing papers in "Virchows Archiv B Cell Pathology in 1970"

Glomerular events during the initial phase of rat Masugi nephritis.

Abstract: Two characteristic glomerular changes were noted in the initial (heterologous) phase of rat Masugi nephritis induced by a single intravenous injection of rabbit NTyG. The one is the neutrophil infiltration as has been observed by many investigators. The other is the mononuclear cell (monocyte) accumulation. Both take place independently but consecutively along the glomerular basement membrane. New evidence on accumulation of monocytes is presented. The glomerular changes are summarized as follows: (1) From two to 12 hrs there was a prominent infiltration of neutrophils and platelets together with an enhanced formation of fibrin thrombi in the capillary lumen. At the ultrastructural level the endothelial layer was dislodged and the neutrophils attached to the denuded basement membrane. Degranulation and destructive changes were observed in the neutrophils. (2) From 12 to 72 hrs neutrophil infiltration and clotting substances were rapidly diminished and a large number of monocytes accumulated in the lumen. These monocytes transformed into macrophages and giant cells. Their role in the removal of intraluminal clotting substances is discussed.

Ultrastructural changes in the motor nerve terminals caused by beta-bungarotoxin.

Abstract: Bungarotoxin, isolated fromBungarus multicinctus (banded krait) venom, induced increased profiles of opened synaptic vesicles at the axolemma, accompanied with decreased numbers of synaptic vesicles and subsequently, almost complete depletion of the vesicles in the axon terminal of motor endplates. The toxin also caused progressive swelling and vacuolization of the mitochondria in the motor nerve endings.

Die Feinstruktur der neuromatösen Neurotisation von Nerventransplantaten

Abstract: In den meisten erfolgreichen Nerventransplantaten mit guter Reinnervation der distalen Nervenabschnitte liegt der Hauptteil der regenerierten Nervenfasern nicht in erhaltenen grosen Faszikeln der implantierten Nerven, sondern in zahlreichen, sehr viel kleineren, vollstandig neugebildeten Faszikeln, die das Bindegewebe der Transplantate wie in einem Neurom ungleichmasig durchsetzen (neuromatose Neurotisation).

Electron microscopic studies of cytoplasmic filaments and fibers in different cell types of fracture callus in the rat

Abstract: Intracellular collagen-like fibers in smooth-surfaced, single membrane-limited, elongated vacuolar structures were demonstrated by electron microscopy in the different types of osteogenic cells of the fracture callus in the rat. The evidence suggested that these fibercontaining vacuoles represented vehicles — perhaps Golgi-derived “condensing vacuoles” —for the transport of intracellularly synthesized, polymerized, and “fibrillized” collagen. It appears that the occurrence of the fiber-containing elements represents a deviation in the normal maturation and structural reorganization process of collagen, perhaps dependent upon the demands for rapid and extensive collagen production in the callus. Abundant intracellular filaments were present in fibroblasts as well as in chondroblasts and other osteogenic cells. These cytofilaments did not differ structurally from similar elements in other cell types, and are probably not directly involved (as precursors, templates, or otherwise) in the elaboration of mature, fiber-structured collagen.

Ultrastructural studies on rat retina damaged by visible light.

Abstract: Adult male rats were exposed to intense, visible light at an elevated body temperature for two periods each of half an hour with an interval of 2 hours in darkness. That treatment caused a highly reproducible degeneration of all the epithelial and photoreceptor cells. The structural changes were investigated by transmission electron microscopy.

Eiweißresorptionstropfen und Lysosomen im proximalen Tubuluskonvolut der Rattenniere

Abstract: Mit der alternierenden intratubularen Ferritin-Ol-Injektion (Modifikation der Methode der gespaltenen Olsaule) wurde der Ablauf der Eiweisresorption wahrend der vacuolaren Phase im proximalen Tubuluskonvolut der Rattenniere untersucht. Die Resorptionszeiten lagen zwischen 1 und 31/2 Std. Als lysosomales Leitenzym wurde saure Phosphatase (acPase) cytochemisch dargestellt. Im Mittelpunkt stand die Frage nach dem Mechanismus der Kontaktaufnahme zwischen resobiertem Eiweis und lytischen Enzymen.

Intestinal mucosal hyperplasia following induced hyperthyroidism in the rat.

Abstract: The administration of thyroid hormone to the rat resulted in hypertrophy of the small intestine The hypertrophy involved the intestinal mucosa to a greater degree than the muscular layer, and was most marked in the jejunum Hyperplasia of surface epithelial cells was associated with possible hypertrophy of microvilli, and an increased histochemical activity of some microvillous enzymes The relationship of these changes to a direct effect of thyroid hormone and to hyperphagia is discussed

Glomerular events during the initial phase of rat Masugi nephritis

Abstract: Two characteristic glomerular changes were noted in the initial (heterologous) phase of rat Masugi nephritis induced by a single intravenous injection of rabbit NTyG. The one is the neutrophil infiltration as has been observed by many investigators. The other is the mononuclear cell (monocyte) accumulation. Both take place independently but consecutively along the glomerular basement membrane. New evidence on accumulation of monocytes is presented. The glomerular changes are summarized as follows: Within 72 hrs both thrombotic changes and monocytic reaction disappeared, then the injured endothelial layer was gradually repaired by elongation of the cytoplasm and by mitosis of the endothelial cells. Thus we could confirm that glomerular injury during the initial phase was mostly repaired in a relatively short time.

Quantitative autoradiographische Untersuchung zur Heterogenität der Leberzellproliferation nach partieller Hepatektomie

Abstract: At different intervals after partial hepatectomy rats were injected with tritiated thymidine, and the labeling index of hepatocytes was determined. The liver lobules were divided into 9 to 12 equally large areas from central hepatic vein to portal fields. Labeling indices were separately counted for each of these subunits. The mode of proliferation is different for special cell groups of the lobule. The peak of cell proliferation 20 h after partial hepatectomy is localized within the peripheral third of the lobule, one tenth of the lobule adjacent to the portal field, however, shows a relatively low labeling index. The decrease of the labeling towards the central vein observed 20 h after operation is almost completely compensated 27 h after partial hepatectomy, only one fifth of the lobule in the central part shows low proliferative activity. As late as 34 to 40 h the peak of the label reaches the inner fifth of the lobule. After low DNA synthesis throughout the lobule 48 h after partial hepatectomy, a new rise of the number of labeled cells occurs 56 h after operation, again preferentially in the periphery with an almost linear decline towards the center. As possible reasons for the proliferative differences endogenous cellular factors and influences of the microenvironment are discussed. It is concluded that the microenvironment within an organ composed primarily of homogeneous cells, almost all of which are capable to proliferate, will determine a topography of optimal conditions for cell proliferation. An der Rattenleber wurde in verschiedenen Intervallen nach partieller Hepatektomie der Thymidin-H3-Markierungsindex der Hepatocyten im Autoradiogramm bestimmt. Die Leberlobuli wurden in 9–12 gleichgrose Flachenareale unterteilt und die Markierungsindices in diesen Lobulusuntereinheiten getrennt ermittelt. Im Proliferationsverhalten der Hepatocyten nehmen einzelne Lobulusareale eine Sonderstellung ein. 20 Std nach Teilhepatektomie liegt das Maximum der Zeilproliferation im peripheren Drittel. Das unmittelbar an das Portalfeld angrenzende Zehntel des Lobulus zeigt dagegen einen geringeren Markierungsindex. Der 20 Std nach Teilhepatektomie nachweisbare steile Abfall des Markierungsindex nach zentral ist 27 Std nach der Operation weitgehend ausgeglichen, lediglich das zentrale Funftel bleibt in der Proliferation zeitlich noch zuruck. 34–40 Std nach Teilhepatektomie ist das Maximum der Zahl markierter Hepatocyten in das zentrale Funftel verlagert. Nach einem vorubergehenden Minimum der DNS-Synthese 48 Std nach partieller Hepatektomie erfolgt ein neuer Anstieg mit erneuter Bevorzugung der Peripherie und etwa linearem Abfall zum Zentrum. Als Ursachen fur das unterschiedliche Proliferationsverhalten werden zelleigene Faktoren und Einflusse des Mikromilieus diskutiert. Die Ergebnisse sind ein Hinweis dafur, das das Mikromilieu innerhalb des Leberlobulus entscheidend den Ablauf der Proliferation beeinflust.

Annulate lamellae in human parathyroid adenoma.

Abstract: Membrane system interpreted as annulate lamellae are found in one parathyroid adenoma from each of two patients with symptoms of hyperparathyroidism. The tumors are light and electron microscopically composed of chief cells with structural signs of varying activity, and rather few oxyphil cells. Annulate lamellae are frequently seen in the chief cells in any portion of the cytoplasm. Sometimes they are very close to the nuclear envelope. The configuration and size of the annulate lamellae vary. They are composed of parallel arrays of double membranes in straight, curved, semi-circular or circular arrangement. The membranes are smooth-surfaced and merge at intervals to form pores. The lamellae are often separated by or surrounded by electron lucent spaces that are continuous with granular endoplasmic reticulum. Mitochondria occur in dilated portions between the double membranes constituting each lamella. Although the close spatial relationship between annulate lamellae and mitochondria may be of coincidental nature, it is believed that the association between these two cellular components is of functional significance.

Der DNS-Gehalt der Zellkerne im Herzohr des Menschen

Abstract: Die histologische Untersuchung der Herzohren von 202 Patienten im Alter von 6–85 Jahren mit Mitralstenose ergab, das in 29% der Falle erheblich vergroserte und z.T. monstrose Zellkerne vorkommen Mit zunehmendem Alter steigt der Anteil der Falle mit hypertrophierten Kernen an. Cytophotometrische Messungen des DNS-Gehaltes an Feulgen-gefarbten Abstrichen von den Schnittflachen von 6 frisch abgetragenen und 4 autoptisch gewonnenen Herzohren ergaben in geometrischer Reihe ansteigende Gesamtextinktionswerte, die Polyploidiestufen entsprechen. Die quantitative Verteilung der verschiedenen Polyploidieklassen ist nicht konstant. Bei einem 11jahrigen Jungen mit Mitralstenose betrug der Anteil der oktoploiden Kerne bereits 32%. Die hochsten gemessenen Werte entsprechen 64- und 96-ploiden Kernen bei einem 47jahrigen Mann. Die Flache der Kerne ist nicht streng mit dem DNS-Gehalt korreliert und variiert innerhalb der Polyploidieklasse derart, das keine abgrenzbaren Grosenklassen auftreten. Diploide und polyploide Doppelkerne zeigen, das Kernteilungen auf allen Polyploidiestufen vorkommen.

The routine demonstration of C cells in human and animal thyroid glands. Value of a simple silver stain.

Abstract: The silver nitrate technique developed by Grimelius was slightly modified in order to obtain a reproducible and simple method for the staining of C cells in the thyroid gland. The reliability of this method was demonstrated by comparing its results with those of immunofluorescent, cytochemical and ultrastructural studies. This staining procedure gives good and permanent results even when applied to tissues first fixed several hours after death. Its use allows the routine evaluation of the number and distribution of C cells in human and animal tissues.

Lipoide Transformation der Mitochondrien in Nebennierenrindenzellen nach Aminoglutäthimid (Elipten® Ciba)

Abstract: Aminoglutethimide (Elipten® Ciba) interferes with the biosynthesis of adrenocortical hormones by blocking the conversion of cholesterol into Δ 5-pregnenolone. The ultrastructural alterations of adrenocortical mitochondria produced by administering Eliptene orally to female albino rats was studied. In almost all adrenocortical layers there was a diffuse transformation of mitochondrial internal structure as the vesicular “fasciculata type” and a mitochondrial enlargement. Such alterations were presumably due to the increase in ACTH-stimulation of adrenocortical cells. The most striking focal mitochondrial changes were intramitochondrial membranebound cavities of different size (diameter up to 6 μ), which should be regarded as a pathological equivalent to mitochondrial vesicles. In electron micrographs the cavities were either empty or contained fine fibrillar or homogeneous lipid material of moderate electron density. At the periphery of this intramitochondrial lipid material myelin-like patterns were often found. After the dissolution of the membranous component of mitochondria, which had undergone “lipoid transformation”, free cytoplasmic lipid aggregates and large lipid droplets developed, frequently with remainders of myelin-like patterns.

Ultrastructural studies on the long term effects of sodium glutamate on the rat retina.

Abstract: Suckling rats were treated with sublethal doses of monosodium-L-glutamate for from one day up to two weeks. The retinae and the optic nerves and tracts were examined after two to ten months by transmission electron microscopy.

Karyokinese und Kernmuster im Herzmuskel wachsender Ratten

Abstract: Hearts of rats from the late prenatal period and first month of life have been investigated with regard to the percentage of altered muscular mitosis in order to explore their part in the modification of nuclear patterns during growth. 1. In the first days after birth the percentage of altered mitosis rises abruptly, later on continuously. Prophase and telophase prove to be particulary vulnerable, which leads to early polyploidization of heart muscle cells. 2. Cell division does not take place after the 22. day of life, some karyokinetic figures still occur beyond the 28. day. Therefore, the definite number of cells is established at the beginning, the number of nuclei in normal heart muscle is essentially fixed after termination of the 4. week of life. 3. Pairs of nuclei, quickly accumulating especially in the second postnatal week, result from the omission of cytokinesis after karyokinesis still being normally performed. 4. There is no indication for amitosis playing any essential role during formation of the organspecific nuclear patterns in heart muscle.

An ultrastructural study of spheroidal nuclear bodies found in gliomas.

Abstract: The morphology of intranuclear bodies observed in human gliomas, is described. The ultrastructural picture varies according to the number of structural components present in every intranuclear body. On this basis they are classified into four types: Type I. Small, filamentous intranuclear body, surrounded by a clear halo. Type II. Intranuclear body larger than type I, showing a filamentous periphery concentrically surrounding a granular center. Type III. Intranuclear body with a filamentous concentric layer around a granular core. Type IV. The largest intranuclear body showing the same three components: core, granular and filamentous layers.

Proliferationsvorgänge in der traumatisch geschädigten Leber

Abstract: Autoradiographic studies were performed withH-3-thymidine in mice to improve the cell proliferation in the liver necrosis after local traumatic injuries. In the normal wound healing, wide spread necrosis in the liver induced only small perifocal zones of proliferative hepatocytes and mesenchym cells three days after trauma with a maximum in the second day.

Elektronenmikroskopische Untersuchungen zur Phalloidintoleranz neugeborener Ratten, Mäuse und Kaninchen

Abstract: 1. Doses of phalloidin that kill adult animals (20 μg/g) are tolerated by newborn rats, mice and rabbits without producing external signs of disease. The livers of newborn animals, however, show the same lesions that were described in adult animals, namely vacuolization of the endoplasmic reticulum and considerable decrease in glycogen. The alterations are marked after 35 min and reach their peak at 4 h. During reparation, between 7 and 48 h, moderately dense, spherical, membrane-limited bodies (diameter ∼0.2 μ), presumably lipid, appear in the cytoplasm. After 24 h, membranebound ribosomes and small quantities of glycogen reappear. 48 h after poisoning, numerous large droplets of lipid appear in the cytoplasm and the number of autophagosomes increases. 12 days after poisoning the fine structure of the liver appears normal. 2. The nucleus, cell membranes, Golgi apparatus, mitochondria, microbodies and lysosomes (with the exception of an increased number of autophagosomes at later periods) were not altered morphologically after phalloidin poisoning. 3. The ultrastructure of the kidney, pancreas, heart muscle and diaphragm was not altered in adult rats and mice after phalloidin poisoning. 4. After treatment with the polypeptide antamanid, phalloidin has little effect on the liver of adult mice. 5. Phalloidin-vacuoles do not show a positive reaction for acid phosphatase, whereas lysosomes do. Lysosomes, therefore, do not appear to be involved in the origin of these vacuoles. 6. According to the “toxication-hypothesis”, phalloidin is assumed to be rendered toxic by drug-metabolizing enzymes. The activity of these enzymes is considerably reduced in rats fed a protein-free diet, but contrary to the “toxication-hypothesis”, the lesions of the liver of rats kept on a protein-free diet are as severed after phalloidin poisoning as those of rats fed a normal diet.

Cytokinetics of argentaffin cells in mouse intestinal mucosa.

Abstract: Diazo-positive cells in mouse duodenal mucosa proliferate only in the same zone as epithelial cells (bottom and lower parts of the crypts). Their rate of proliferation as well as their speed of migration into the villi are slower than those of epithelial cells, but to a minor extent only. It is suggested that a special cytokinetic behaviour appears earlier than morphological argentaffin differentiation.

Celluläre Autophagie: Glykogensegregation im Frühstadium einer partiellen Leberatrophie

Abstract: Bei ausgewachsenen Ratten wird durch Unterbindung eines kleinen Pfortaderastes die linke Halfte des mittleren Leberlappens (10–15% der Leber) aus der portalen Zirkulation ausgeschaltet. In den ersten Stunden danach beobachtet man in lappchenperipheren Epithelien des portalischamischen Gewebes zahlreiche autophagische Vacuolen, die in wechselndem Ausmase, und nicht selten ausschlieslich Glykogen enthalten. Sie konnen bei der Reaktion auf saure Phosphatase fermentpositiv sein. Die Glykogensegregation im Rahmen einer gesteigerten cellularen Autophagie hat einen hinreichenden Glykogengehalt der Zelle zum Zeitpunkt des Insultes zur Voraussetzung. Sie ist keine spezifische Reaktion auf bestimmte Noxen, da Glykogen in geringem Umfange schon physiologischerweise segregiert wird. Generell gibt es zwei Ursachen fur eine Anhaufung von Glykogen in Vacuolen: 1. eine gesteigerte cellulare Autophagie, wie in den eigenen und anderen Untersuchungen; 2. eine Storung im hydrolytischen Abbau des unter Normalbedingungen segregierten Glykogens, wie bei der Glykogenose Typ II. Segregiertes Glykogen kommt unter den Versuchsbedingungen auch innerhalb tubulo-vesicularer Formationen vor, die das morphologische Spektrum der cellularen Autophagie erweitern.

Quantitative and qualitative changes of structure and ultrastructure of intestinal epithelia during incubation in vitro

Abstract: Quantitative and qualitative changes in jejunal epithelial cells of “everted sac” preparations, incubated in vitro in an aerated physiological buffer for 0, 5, 10, 15, 30 min, 1, 2, and 3 h, are described: (a) mean section width, (b) height and (c) volume of cells; (d) volume fraction of mitochondria and (e) of nuclei; (f) mitochondrial axes; (g) absolute volume of single mitochondria.

[Development of experimental liver cirrhosis by D-galactosamine. Histological, biochemical and autoradiographic studies in rats].

Abstract: Intraperitoneal injections of D-galactosamine. HC1 in rats produce chronic progressive hepatitis that leads within six months to cirrhosis. The pathological process starts with focal necroses of parenchyma and periportal proliferation of mesenchymal cells and bile ducts. During this initial phase the serum enzyme activities are not considerably elevated. In the stage of cirrhosis the parenchymal alterations are less pronounced while autoradiographic analysis after administration of thymidine-3H shows an increasing proliferation of mesenchymal cells. In contrast to the increased regenerative proliferation of the epithelial cells in the precirrhotic stage, a different intensity of proliferation is observed in parenchymal nodules. That indicates a focal alteration of tissue differentiation. After galactosamine administration for 6 months the liver glycogen and glucose contents are reduced significantly, whereas the ATP1 level is normal. The changes in concentrations of uridine phosphates (UTP, UDP, UMP), UDP-sugars, and of galactosamine metabolites show an adaptation of uracil nucleotide and galactosamine metabolism in chronically galactosamine treated rat liver. The immune suppressive compound Azathioprin does not influence the development of liver cirrhosis. Durch intraperitoneale Injektionen von D-Galaktosamin HC1 wird bei Ratten innerhalb von 6 Monaten uber das Stadium der chronisch fortschreitenden Hepatitis eine Lebercirrhose erzeugt. Dieser Prozess beginnt mit einer Leberparenchymschadigung und periportaler Mesenchymzell- und Gallengangswucherung. In diesem Zeitraum sind die gemessenen Serumenzymaktivitaten nicht wesentlich erhoht. Im Stadium des cirrhotischen Umbaus stehen die Veranderungen am Parenchym im Hintergrund, wahrend autoradiographisch eine zunehmende Mesenchymzellproliferation zu beobachten ist. Im Gegensatz zur regenerativen Steigerung der Epithelproliferation im pracirrhotischen Stadium weist die unterschiedlich starke Proliferation in den insularen Regeneraten auf eine herdformige Anderung der Gewebsdifferenzierung hin. Der Glykogen- und Glucosegehalt der Leber ist nach 6monatiger Galaktosaminbehandlung signifikant vermindert, der ATP-Spiegel jedoch normal. Die Veranderungen der Konzentrationen der Uridinphosphate (UTP, UDP, UMP), der UDP-Zucker und von Metaboliten des Galaktosamins zeigen eine Anpassung des Uracilnukleotid- und Galaktosaminstoffwechseis an das langdauernde Galaktosaminangebot. Versuche mit der immunsuppressiven Substanz Azathioprin zeigten keinen Einflus auf die Entwicklung der Lebercirrhose.

Effect of Trenimon on the ultrastructure of Sertoli cells in the mouse.

Abstract: Adult male mice were used to study the effect of Trenimon on the testis at light microscopical and ultrastructural level. Two groups under acute and prolonged experimental conditions respectively were studied. The first change observed was marked cytoplasmic vacuolation in Sertoli cells. In a later stage injured germinal cells, specially spermatocytes and spermatogonia, were scattered throughout the seminiferous epithelium and some phagocytized by the adjoining Sertoli cells, where the complete involution took place. A combined mechanism of Trenimon direct action on germ cells and a disturbance in the relationship Sertoli cell-germ could be suggested as the cause of germinal injury.

Über Endocytose in Kupfferschen Sternzellen nach Parenchymschädigung durch 3÷4-Teilhepatektomie

Abstract: 2 and 6 hours after 3÷4-resection of rat liver many Kupffer-cells show signs of an enhanced endocytic activity. This activity is the reaction to parenchymal cell damage which is characterized by defects in the plasma membrane and by release of cytoplasmic debris into the space of Disse and the sinuosid. Such picture are interpreted as a partial lysis of the cell periphery. The plasma membrane of many Kupffer-cells is coated with a layer 500 to 600 A thick, which stains with silver-methenamine and is thought to be glycocalyx. Ribosomes, as a part of the cellular debris, are often adsorbed to that layer. Cleftlike infoldings of the surface, which represent a stage of puresurface endocytosis, give the picture of double profiles of 1,200 A thickness; the adsorbed ribosomes form a characteristic median stripe. Double profiles sometimes occur between two closely apposed Kupffer-cells. By means ofmixed type endocytosis large vacuoles (max. 7μ∅) arise which contain fluid and debris; their wall is coated over the inner side with the layer and adsorbed ribosomes. These vacuoles are acid phosphatase negative. Larger particles, such as liver-cell mitochondria, are sometimes ingested by Kupffer-cells without participation of a specialized adsorptive layer. In den ersten Stunden nach erweiterter Teilhepatektomie (3÷4-Resektion) weisen zahlreiche Sternzellen feinstrukturelle Zeichen einer gesteigerten Endocytoseaktivitat auf. Sie ist die Reaktion auf eine Parenchymlasion, bei der Bestandteile des Cytoplasmas uber Defekte in der Plasmamembran in den Disseschen Raum und in das Sinusoid gelangen, und die als partielle Lyse der Zellperipherie aufgefast wird. Die Plasmamembran der Sternzellen ist vielfach ausen mit einer 500–600 A breiten Schicht bedeckt, die sich mit der Silbermethenamin-Reaktion hervorheben last, und die eine besonders entwickelte Glycocalyx darstellt. An diese Schicht sind haufig aus geschadigten Leberepithelien stammende Ribosomen adsorbiert. Enge Einfaltungen, die eine reineOberflachenendocytose reprasentieren, stellen sich im Schnitt als 1200 A breite Doppelprofile dar; die adsorbierten Ribosomen bilden einen charakteristischen Mittelstreifen. Gleichartige Doppelprofile stellen manchmal auch die Grenzzone zwischen zwei Sternzellen dar. Durchgemischte Endocytose entstehen Vacuolen (bis 7 μ∅), die Zellschutt enthalten, und deren Wand innen mit der Schicht und daran adsorbierten Ribosomen bedeckt ist. Sie sind saure Phosphatase-negativ. Grosere Partikel, wie Leberzellmitochondrien werden auch ohne Beteiligung der 500–600 A breiten Adsorptionsschicht in Sternzellen aufgenommen.

Thyroid C cells in experimental hyper- and hypomagnesaemia.

Abstract: The thyroid C cells of magnesium-deficient and magnesium-loaded rats were investigated by optical, ultraviolet and electron microscopic techniques.

Growth of elementary blood vessels in diffusion chambers. I. Process of formation and conditioning factors.

Abstract: 1. An electron microscopical analysis of the development of new capillary structures from vascularized (omentum) or avascularized (cardiac valves) rat tissue expiants in diffusion chambers placed in rat peritoneal cavity, has shown that the solid precapillary structures previously described (Aloisiet al., 1970) are always multicellular in nature, even when they appear as syncytial to the light microscopy. 2. The nature of the cells composing the solid pre-capillary structures appears to be different from that of common fibroblasts, an evolution of the latter to endothelial-like cells being nevertheless not excluded. 3. In these pre-capillary structures cellular differentiations take place precociously and lead to pericyte formation on the outer side and to degeneration of the inner cells. 4. The formation of a capillary lumen is therefore associated to such degenerative changes, and to the shedding and dissolution of the inner cells, a process which, combined with the apposition of new endothelial cells from outside may also account for the widening of the newly formed elementary vessel. 5. The morphogenetic value of these regressive phenomena in the formation of capillary lumina is discussed, as analogous to other phenomena in the embryo and particularly reminiscent of the formation of embryo vasculature from angioblast and from other mesenchymal anlagen.

Isolierung und Untersuchung von Einschlußkörperchen in der Rattenniere nach chronischer Bleivergiftung

Abstract: During chronic lead poisoning over a period of 10 respectively 13 months intranuclear, eosinophilic inclusion-bodies developed in the epithelial cells of the proximal convoluted renal tubules. These bodies were isolated by gradient centrifugation, washed, lyophilized, and incinerated for the analysis of lead. Lead was determined by atomic absorption spectrophotometry. 13 respectively 38 mg of lead per g dry weight of isolated inclusion bodies were found corresponding to a more than 70fold enrichment of lead in these inclusion bodies as compared to the total kidney.

Deposits of granular material in mitochondria. Electron microscopic observations in neoplastic cells oa a malignant melanoma of the human uveal tract.

Abstract: It has been shown inin vitro experiments that isolated mitochondria are able to absorb large amounts of calcium in addition to other divalent cations if ATP has been added to the culture medium (Engstrom and De Luca, 1964). This absorption is accompanied by ultrastructural changes in the form of electron dense granules in the matrix of the mitochondria, much larger and more numerous than the granules usually observed in mitochondria (Greenawaltet al, 1964; Peachey, 1964; Reynolds, 1965). In addition, electron microscopic studies have disclosed similar intramitochondrial granules in osteoclasts (Gonzales, 1961), in the epithelium of the renal tubules after administration of parathyroid hormone (Gaulfield, 1964), and in liver cells after poisoning by carbon tetrachloride (Reynolds, 1965). In the latter cells an increased calcium content was also demonstrable in the mitochondrial fraction after ultracentrifugation. The object of the present paper is to describe in neoplastic cells the presence of intramitochondrial granules that are indistinguishable morphologically from those found by the above workers.