Electron microscope observations on intracellular virus-like particles associated with the cells of the Lucké renal adenocarcinoma

MOUSE CYTOMEGALOVIRUS INFECTION. AN ELECTRON MICROSCOPIC STUDY OF HEPATIC PARENCHYMAL CELLS

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Electron microscopy of junco pox

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The ultrastructure of the kidney in lead intoxication with particular reference to intranuclear inclusions

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ELECTRON MICROSCOPY OF SALIVARY GLAND VIRUSES

A human and a mouse strain of the salivary gland virus have been examined by electron microscopy. The human strain was transmitted, prior to examination, to tissue cultures derived from human myometrial cells, while the mouse strain was examined in mice inoculated intraperitoneally. The nuclear forms associated with both strains of virus were morphologically similar. Nuclear inclusions, composed of particles interspersed with dense clumped chromatin, were a striking feature of infected cells. The cytoplasmic forms were of 2 types-one a 300 to 500 mmicro homogeneous dense spherical form, and the other a target-like form composed of a central dense dot in a pale zone surrounded by a dense shell-the entire configuration measuring 100 to 180 mmicro. The target-like particle appeared to be identical in both strains. The spherical cytoplasmic forms in cells infected with the human strain appeared to be solid, while in cells infected with the mouse strain there was evidence of formation of target-like forms within the spheres. Possible mechanisms by which infection of the cell may occur, as well as possible mechanisms and sites of multiplication of virus, are discussed.

Electron Microscope Study of a Cell-Free Induced Leukemia of the Mouse: A Preliminary Report

Preliminary results of an electron microscope study of a leukemia of the mouse transmissible by cell-free filtrates are reported. In twelve out of forty-seven specimens examined, virus-like particles were observed. So far, these particles have not been observed in control, non-leukemic animals. They are located inside the cytoplasm of leukemic cells which infiltrate the spleen or the liver. Their diameter is approximately 78 mmicro. Their resemblance to other particles recently described in different mouse tumors is stressed. Their significance and, in correlation with ultrafiltration data, their possible etiological meaning are discussed.

Observations on the Fine Structure of the Turtle Atrium

The general fine structure of the atrial musculature of the turtle heart is described, including; the nature of the sarcolemma; the cross-banded structure of the myofibrils; the character of the sarcoplasm, and the form and disposition of its organelles. An abundant granular component of the sarcoplasm in this species is tentatively identified as a particulate form of glycogen. The myocardium is composed of individual cells joined end to end at primitive intercalated discs, and side to side at sites of cohesion that resemble the desmosomes of epithelia. Transitional forms are found between desmosomes and intercalated discs. Both consist of a thickened area of the cell membrane with an accumulation of dense material in the subjacent cytoplasm. This dense amorphous component is often continuous with the Z substance of the myofibrils and may be of the same composition. The observations reported reemphasize the basic similarity between desmosomes and terminal bars of epithelia and intercalated discs of cardiac muscle. Numerous unmyelinated nerves are found beneath the endocardium. Some of these occupy recesses in the surface of Schwann cells; others are naked axons. No specialized nerve endings are found. Axons passing near the sarcolemma contain synaptic vesicles, and it is believed that this degree of proximity is sufficient to constitute a functioning myoneural junction.

Electron microscopic observations of amoeba proteus in growth and inanition

Electron microscopic observations have been made on growing and dividing specimens of Amoeba proteus and also on starving animals. Structures presumably corresponding to the mitochondria, alpha particles, vacuoles, and Golgi material are described. A new entity, designated as a foamy particle, is noted. Descriptions are given of the cytoplasmic and nuclear membranes. During division the inner, thick nuclear membrane component is seen to vanish and the outer membrane persist. Measurements suggest a gradual reappearance of the inner component with growth. Starving animals show a loss of cytoplasmic granularity and an increase in the electron density of mitochondria, presumably due to lipide accumulation.

Fluorescent antibody detection of the antigens of the Shope papilloma virus in papillomas of the wild and domestic rabbit

The results obtained by a fluorescent antibody study of the Shope papilloma virus in papillomas of the wild and domestic rabbit are presented. In the wild rabbit papillomas the viral antigens occurred exclusively in the nucleus and were present in the differentiating cells of the keratohyaline layers and in the keratinized layers. The antigens were not present in the deeper proliferating epithelial cells of the papillomas. The Shope viral antigens were present in very minute amounts in papillomas of the domestic rabbit, as compared with papillomas of the wild rabbit, and were only detected in the superficial keratinized layers. It is postulated that virus is present in the nuclei of the proliferating cells of the papillomas of the wild and domestic rabbit but exists there in an early stage of development, consisting mainly of nucleic acid and deficient in protein, therefore non-antigenic and not demonstrable by fluorescent antibody. The nucleic acid moiety of the virus may be infective, and the protein component may provide immunologic specificity and serve to preserve transmissibility. The protein-deficient virus can be referred to as masked virus.