Intranuclear filamentous inclusions in the gastro-entero-pancreatic (GEP) endocrine cells of birds

Summary Intranuclear filamentous inclusions were found in the normal endocrine cells of the avian stomach and pancreas. These inclusions were composed of a bundle of closely packed filaments (6–8 nm in diameter), being ultrastructurally similar to those found in the nucleus of various neurons. Most of them appeared as single rod- or spindle-shaped bodies; aggregations of two or more inclusions were rarely seen within a single nucleus. Cells with an intranuclear inclusion often contained a cytoplasmic fibrillar bundle similar to the intranuclear inclusion.     

Intranuclear Inclusions in the Ameboid Cells of Protostelium zonatum*

SYNOPSIS. Two morphologically distinct types of intranuclear inclusions are found in ameboid cells of the protostelid mycetozoan Protostelium zonatum. One type of inclusion is a coiled tubular structure which in cross section appears as cisternae and oval to elliptical vesicles 40–60 nm in diameter. These tubular and vesicular structures are formed by a unit membrane that is connected directly with the inner nuclear membrane. The other type of inclusion is a membrane-bound structure that contains amorphous and/or fibrous material. These inclusions usually are present at several locations in a nucleus. No similar structures occur in the cytoplasm.     

Fine Structure of Cellular Inclusions in Pericarp Cells of Polysiphonia deusta (Ceramiales, Rhodophyta)

The ultrastructure of cytoplasmic inclusions in pericarp cells(cystocarpic plant) of Polysiphonia deusta shows five structuraltypes of inclusions; (1) membrane-bounded crystalloid inclusionsthat are composed of tetragonally packed fibrils, each 8 nmdiam., spaced 17.5 nm between centres; (2) membrane-boundedcrystalloid-like inclusions with incomplete structure; (3) unboundedcrystalline body without a distinct crystal lattice pattern;(4) membrane-limited fibrillar inclusions; (5) fibrillogranularstructure. The membranes of the first two inclusions were coveredwith ribosomes and seem to be elements of endoplasmic reticulum. Polysiphonia deusta, pericarp cells, cellular inclusions     

ELECTRON MICROSCOPIC OBSERVATIONS ON TUBULAR STRUCTURES INVOLVED IN CRYSTAL FORMATION IN THE RED ALGA PLEONOSPORIUM SQUARRULOSUM (HARV.) ABBOTT1

Hexagonal or angular crystalline inclusions in Pleonosporium (Naeg.) Hauck vegetative cells were examined using electron microscopy. Ultrastructural analysis reveals that the inclusions initially contain tubular elements resembling microtubules but, with continued differentiation, are transformed into rod containing crystals. The tubular structures initially measure 25 nm in diameter. Scattered tubules become arranged in a parallel and alternate pattern and undergo subsequent enlargement to approximately 29 nm. Following enlargement, each tubule apparently disaggregates into rods that form a crystal having hexagonally arranged rod-like subunits. It is suggested that these tubules may represent microtubules and the resultant crystals are composed of tubulin.     

A new virus associated with the parasitoid Cotesia marginiventris (Hymenoptera: Braconidae): Replication in noctuid host larvae

A nonoccluded filamentous baculo-like virus occurred in scattered hypodermal and tracheal matrix cells of five species of noctuid larvae (Spodoptera frugiperda, S. exigua, S. ornithogalli, Heliothis zea, and Trichoplusia ni) parasitized by Cotesia (= Apanteles) marginiventris. Infected cells and their nuclei were moderately hypertrophied. Infected cells contained prominent virogenic stromata, fibrous cytoplasmic inclusions, and moderate numbers of a filamentous virus. Virions were 50–98 nm in diameter, ≥865 nm in length, and straight to slightly flexuous. Nucleocapsids were 30–39 nm in diameter with a core 21–24 nm in diameter, and were enclosed by one or two envelopes. Nucleocapsids occurred in the nuclei and in the cytoplasm. Enveloped nucleocapsids were restricted to the cytoplasm.     

Intranuclear inclusions in the developing neurons of the rat cuneate nuclei

Summary The ultrastructure of intranuclear rodlets, microtubules, fibrillar lattices and membranous inclusions found in the developing cuneate nuclei of rats is described. Rodlets, ranging in diameter from 96–312 nm and in length from 1–2 m, are made up of tightly packed straight filaments measuring 5–8 nm in diameter. Microtubules with a diameter of 26 nm are clustered together. Fibrillar lattices are made up of fibrils with a diameter of 9 nm arranged in layers or sets. Two to nine sets make up a lattice, with a maximum width of 68 nm, in which the adjacent sets are arranged at an angle to each other. Rodlets and fibrillar lattices occur in 6.8% of the neurons. Membranous inclusions, reported here for the first time in normal neurons, are of 2 types: small vesicles of 0.1–0.6 m and large vacuoles measuring 1–2 m. Both types are bounded by either a single or a double membrane and generally have an electron lucent content. Membranous inclusions occur in 25.3 % of the neurons. Changes in the frequency of occurrence of the various intranuclear inclusions in the course of postnatal development are also reported.     

Unusual mitochondrial ultrastructure in the pig adrenal cortex

Unusually large mitochondria with few cristae were observed in the cells of the boundary layer between the zonae fasciculata and reticularis of the pig adrenal. These mitochondria occasionally contained parallel arrays of beaded filaments which appeared to be composed of repetitive electron opaque particles, measuring 10 to 11 nm in diameter. The possibility that these filaments are arranged in closely packed arrays of tubular structures with a central filament is discussed.     

Observations on eosinophilic granule cells in peritoneal exudates of eels, Anguilla amtmlis

Eosinophilic granule cells (EGC) are reported among peritoneal exudate cells (PEC) of unstimulated and carrageenan-, zymosan-, latex- and Aeromonas hydrophila -stimulated eels, Anguilla australis . At the light microscopy level EGC are large (< 50 μm diameter) and have strongly to moderately basophilic cytoplasm, eosinophilic granules, and often striated colourless cytoplasmic inclusions. Ultrastructurally, the cytoplasm is rich in ribosomes, and contains characteristic granules, parallel tubular structures 46–50 nm in diameter, and parallel rod-like arrays (PRLA) 14–15 nm in diameter that are angular or hexagonal in cross section. EGC contain granule-associated, partially or completely cyanide inhibited, but azide and aminotriazole resistant, peroxidase, acid phosphatase, esterases and weak cytoplasmic periodic acid-Schiff positivity. PRLA lack enzyme content. A few (< 10%) unstimulated and carrageenan- and zymosan-stimulated EGC contain granule-associated and diffuse β-galactosidase, and EGC in eels injected i.p. with filtered carrageenan-stimulated PEC supernatants show heterogeneity in glucosaminidase content.     

Elektronenmikroskopische Untersuchung Tubulärer Strukturen in den Kernen der Blattzellen von Selaginella Martensii

Summary In the light microscope the nuclei of the leaf cells of Selaginella martensii show ring-shaped inclusions. These rings are Feulgen positive and most probably contain DNA. An electron microscopic examination of these ring-shaped inclusions shows that they are composed of closely packed tubular elements which have a constant diameter and unknown length. These bundles are often surrounded by a number of larger tubular elements which may be built up of tubular subunits.

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Elektronenmikroskopische Untersuchung Tubulärer Strukturen in den Kernen der Blattzellen von Selaginella Martensii

Zusammenfassung Die Kerne der Blattzellen von Selaginella martensii zeigen im Lichtmikroskop ringförmige Einschlüsse. Diese Ringe sind Feulgen-positiv, enthalten also wahrscheinlich DNS. Sie bestehen aus einem dichtgepackten Bündel tubulärer Elemente konstanten Durchmessers, jedoch nicht genau bestimmbarer Länge. Die Ringe sind häufig von einer wechselnden Zahl größerer tubulärer Stränge umgeben, die aus röhrchenförmigen Untereinheiten bestehen können.

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Direktor: Prof. Dr. A. Frey-Wyssling

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(Prof. Dr. W. Haupt)     

Ultrastructural changes during propagation of a Group D streptococcal L-form

Summary L-form colonies derived from a Group D streptococcus showed alterations in fine structure during propagation. For the first 6 months after preparation the L-forms were capable of reversion and fibrillar and lamellate inclusions were found in some cells. Fibrillar bundles, composed of fibrils with an external diameter of 12.5 nm were found attached to the cytoplasmic membrane of the large 20 m surface cells. Small, 1 m cells within the agar contained lamellate inclusions with a periodicity of 14 nm, also attached to the cytoplasmic membrane. In empty cells both inclusions appeared as hollow fibrils. The composition of these structures is not known. Long filamentous evaginations of the cytoplasmic membrane were also found in a small proportion of cells. After 15 months' propagation, when the L-form had become stable, the inclusions and filaments were no longer visible.     

Electron microscopic observations of an unusual cytoplasmic inclusion in the calcium-starved white mutant (LU887 × LU897) of Physarum polycephalum

Electron micrographs of Physarum polycephalum microplasmodia (LU887 × LU897) reveal cytoplasmic inclusions that appear “striated” at low magnifications; at higher magnifications these exhibit a structure that we have interpreted as microtubule bundles. The light and dark regions in the inclusions are due to the affinity of some microtubules for osmic acid; these appear to have dense regions while other microtubules remain electron lucent. The diameters of the microtubules are about 32–33nm; the subunits forming the tubule walls measure about 8–9nm in diameter. The diameter measurements are slightly larger than the dimensions assigned to vertebrate microtubules (28nm); however, the diameter of the subunits in the microtubule wall measures about 8–9nm which is essentially the same measurement reported for vertebrate tubulin dimers.     

Tubular inclusions within polyploid nuclei ofGerris najas do not react with a monoclonal anti-β-tubulin antibody

Summary Variable aggregates, composed of tubules with a mean diameter of 19 nm, were found exclusively within polyploid nuclei of the midgut, Malpighian tubes, cyst cells, testis epithelium, and trophocytes ofGerris najas. The nuclear inclusions are always in direct contact with the nucleoplasm, and no other structures are associated with them. They appear most abundant within degenerating nuclei of the midgut surface epithelium, where they form paracrystalline bodies or spindle-shaped inclusions with tapered ends. Smaller fusiform inclusions occur in younger epithelial nuclei but not in the diploid nuclei of regenerative cells. In other tissues, mainly spindle-shaped inclusions can be observed, the longest (4.5 m) in cyst cell nuclei. The mean diameter of the tubules determined from transverse sections, resembles that of cytoplasmic microtubules and was verified statistically. The inclusions within trophocyte nuclei failed to react with monoclonal anti--tubulin antibody, although the antibodies could penetrate the nuclei after extensive lysis of the cells.     

Intracisternal tubules and intramitochondrial filaments in cells of a snail, Limnaea

Epithelial and peritubular cells associated with the reproductive tract of the snail, Limnaea stagnalis, contain an extensive system of endoplasmic reticulum that is often dilated with many closely packed intracisternal tubules. The intracisternal tubules are approximately 24-28 nm in diameter and they are often hexagonally packed. They have a two-layered wall, possess fine interconnections, and extend linearly for considerable distances, but angular bends in the tubules also occur. Mitochondria in the peritubular cells contain solid, filamentous structures 9-12 nm in diameter and triangular-shaped structures when sectioned in the mitochondrial matrix.     

Membranous Inclusions of Pseudomonas aeruginosa

Electron microscopy of sectioned cells of Pseudomonas aeruginosa treated with a double fixative in N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid revealed a number of membranous inclusions varying in size and morphology. One round, electron transparent form was frequently observed which did not routinely appear to be attached to the cytoplasmic membrane and varied in size from 120 to 300 nm in diameter. However, in one case, several tubular structures between an inclusion and the cytoplasmic membrane was observed. On rare occasions, a large and unusual multilayered inclusion consisting of three thick and distinct layers was also encountered. In addition, two small mesosomal structures were singly observed in cells and were situated proximal to the cytoplasmic membrane. One type appeared to consist of a single thin membrane, whereas the other type consisted of a delicate, multilayered structure.     

Ultrastructure of freeze-substituted hyphae of the basidiomyceteLaetisaria arvalis

Summary The ultrastructure of freeze-substituted (FS) hyphae ofLaetisaria arvalis is described and compared to that of similar hyphae preserved by conventional chemical fixation (CF). The outline of membrane-bound organelles as well as the plasma membrane was smooth in FS cells. In contrast, hyphae preserved by CF exhibited membrane profiles that were extremely irregular. Centers of presumed Golgi activity were best preserved by FS. Microvesicles, 27–45 nm diameter and hexagonal in transverse section, were observed most readily in FS cells. Filasomes (= microvesicles within a filamentous matrix) were only observed in FS cells. Apical vesicles, 70–120 nm diameter, associated with the centers of Golgi activity and within the Spitzenkörper region exhibited finely granular matrices in FS hyphae, whereas in CF hyphae the contents were coarsely fibrous and less electron-dense. Microvesicles were present at hyphal apices and regions of septa formation. Filasomes were also found at regions of septa formation as well as along lateral hyphal tip cell walls. Microvesicles, but not filasomes, were observed in membrane-bound vesicles (= multivesicular bodies) and in larger vacuoles. Filaments, 5.2–5.4 nm wide, were juxtaposed with centripetally developing septa. Cytoplasmic inclusions, 20–40 m in length, composed of bundles of 6.7–8.0 nm wide filaments were observed in both FS and CF hyphae.     

The ultrastructure of inclusions inVinca nuclei

Summary An electron microscopic study of leaf and petal mesophyll tissue ofVinca rosea revealed the presence of nuclear inclusions. The inclusions were found to be tubular with an outside diameter of about 100 Å. The tubular inclusions inVinca appear to be similar to those that have been described in nuclei of other plants.     

Die Feinstruktur kristalloider Einschlüsse in Mitochondrien von Porterioochromonas stipitata

Summary The matrix of the mitochondria of Porterioochromonas stipitata Lewin (Chrysophyceae) often contains crystalloid inclusion bodies that are composed of hexagonally packed fibrils (or tubules). The fibrils have a diameter of 10 nm, their center-to-center spacing is 13,5 nm.     

Ultrastructural and cytochemical investigations on the functional role of proteinaceous nuclear inclusions (PNIs) in chlorenchyma plant cells

Summary— Detailed investigations on the fine ultrastructural organization of different forms of proteinaceous nuclear inclusions (PNls) in chlorenchyma plant cells suggest they consist of the same elementary subunits. Previous high magnification of TEM micro-graphs had shown that the amorphous type of inclusion (A) was mainly composed of elementary fibrils measuring 3.0–3.5 nm in diameter, with no orderly spatial arrangement. New computer image treatments of electron micrographs allowed us to establish that the 8.0–13.0 nm thick filaments — forming the fibrillar (F), crystalline (C) and lamellar (L) inclusions — consist of two elementary fibrils which are coiled in a helix with variable pitch, depending on the type of inclusion. A further secondary coiling of two filaments, about 8.0–9.0 nm in diameter, gives the 20.0–25.0 nm thick tubules which form the characteristic tubular inclusion (T). Correlating the distributive data of PNIs with observations on their ultrastructural morphology and with micrographs of partial aggregation or disgregation patterns of the inclusions, led to the hypothesis that the different forms are not different classes of proteins, but simply different stages of structural complexity of the same protein. To determine whether the intranuclear inclusion protein is nucleolar or nucleolus-associated, cytochemical and immunocytochemical tests were performed on ultrathin sections or leaf lamina tissue in block. These techniques proved that PNIs do not belong to the class of argyrophilic proteins (AgNOR-proteins), and particularly not nucleolin and fibrillarin, two of the major nucleolar proteins. Structural similarities to other plant inclusions, especially P-proteins, and to animal and plant intermediate cytoskeletal filaments (IFs) are discussed with regard to the functional role of PNIs.     

The morphology of multivesicular bodies in soybean protoplasts and their role in endocytosis

Summary Multivesicular bodies (MVBs) in soybean protoplasts are distinct organelles (generally 250–500 nm in diameter) consisting of a limiting membrane and a number of smaller internal vesicles (generally 40–100 nm in diameter). MVBs of soybean protoplasts are morphologically similar to MVBs of animal cell systems. They can have tubular protuberances which extend from the main body of the organelle and a lamellar plaque on the cytoplasmic surface of their limiting membrane. In addition, the internal vesicles can be labeled by a zinc iodide-osmium tetroxide postfixation and may form via invagination of the limiting membrane.The MVBs of soybean protoplasts are a major compartment in the endocytotic pathway. They accumulate, over time, exogenously applied cationized ferritin and may deliver it to the major lysosomal or lytic compartment of the plant cell, namely, the vacuoles.     

Hepatocellular fibrinogen storage in familial hypofibrinogenemia

In the cytoplasm of hepatocytes of liver biopsy from a 30 year old man, there were proteinaceous inclusions which by use of the peroxidase-antiperoxidase method reacted strongly with antihuman-fibrinogen IgG, but gave a negative reaction with antihuman-alpha-1-antitrypsin IgG and with antihuman-albumin IgG. As shown in the electron microscope, these protein inclusions were composed of densely packed, irregularly arranged tubules of 40 nm diameter. Clinically, the patient and members of his family showed primary hypofibrinogenemia which on the basis of the morphological findings has to be interpreted as the consequence of a disturbance in the secretion of fibrinogen. Besides the well known alpha-1-antitrypsin deficiency, familial hypofibrinogenemia with hepatocellular fibrinogen storage appears to represent another example of a plasma deficiency due to failure of hepatic secretion.