Metaphysis of mice after the incorporation of 224Ra.

Osteocytes from the proximal tibial metaphysis of mice were examined by electron microscopy at various time intervals after the incorporation of 1, 1.5, or 5 μCi/kg of body weight 224Ra. The animals were sacrificed 2 hr, 24 hr, or 5 days following administration of the short lived bone seeking radionuclide. Only the younger, osteoblast like osteocytes from the undecalcified trabecular bone were studied. Compared with the osteocytes from bone tissue of control animals, about half of the cells examined in specimens from animals treated with 224Ra showed ultrastructural alterations. In the nuclei of many osteocytes the chromatin was condensed. The mitochondria showed various signs of damage such as loss of cristae, swelling, and dissociation or disruption of both limiting membranes. Additionally, giant mitochondria were found. The rough surfaced endoplasmic reticulum was sometimes dilated and formed large cisternae. The Golgi complex was vacuolated. The pericellular spaces of lacunae containing severely damaged osteocytes were enlarged. It is thought that the early ultrastructural changes in osteocytes from the trabecular bone of mice resulted from the effects of direct irradiation upon the cells. Probably, all osteocytes which showed lesions were situated within the range of the α radiation emitted from the incorporated 224Ra which was randomly distributed in the mineralized bone matrix of the trabeculae. The mitochondria of the osteoblast like osteocytes appeared to be the cellular organelles most sensitive to the effects of 224Ra administration

So called annular gap junctions in bone cells of normal mice.

Spherical bodies consisting of a granular matrix and a pentalaminar limiting membrane were found in cells from the proximal tibial metaphysis of normal mice. The unusual pentalaminar membrane limiting the bodies was not modified in its preservation by the various fixatives used. The membrane consisted of an innermost and outermost electron dense layer, both similar to the outer leaflets of a unit membrane. Between these 2 layers, an intermediate punctuated one was to be seen. This leaflet seemed to consist of periodically arranged subunit particles appearing in cross section as a chain of electron dense dots. It was separated from the innermost and outermost electron dense leaflet by an electron lucent layer on either side. The 5 layered membrane was approximately 20 nm thick. Its multi layered composition was identical with that of intercellular gap junctions ('tight junctions') occasionally observed between cells from trabecular bone tissue. The structures measured about 280-570 nm in diameter and were located mainly in the cytoplasm of osteoblasts and occasionally in preosteoblasts. The granules within the bodies resembled ribosomes. The multi layered composition of the limiting body membrane was identical with that of intercellular gap junctions

Intracisternal crystalline arrays of coated parallel tubules in cells of a human osteosarcoma.

Crystalline arrays of coated parallel tubules (CPT) were observed by electron microscopy within dilated cisternae of the rough endoplasmic reticulum of pleomorphic mononuclear cells in a human osteosarcoma. The wall of the peculiar intracisternal tubules consisted of an electron-dense thin membrane-like envelope which appeared to be composed of granular subunits. The electron-lucent tubular core together with the limiting envelope was approximately 15 nm in diameter. A coat of fuzzy material, approximately 10 nm thick, tightly surrounded the membrane-like wall of the tubules. Cross sections of accumulations of CPT showed the tubules to be arranged in a hexagonal crystalline array. The nature and significance of the intracisternal CPT are unknown

Intranuclear vermicellar bodies in human osteosarcoma and ossifying fibroma cells.

Electron microscopic investigation of 16 cases of human bone tumor revealed the presence of intranuclear vermicellar bodies (IVB) in cells of two osteosarcomas and one ossifying fibroma. The spherical nuclear inclusions consisted of electron-dense, interwoven, threadlike structures measuring approximately 20-30 nm in diameter. The nature and significance of the IVB remain obscure at present

Pleomorphic C-type virus particles in bone tissue of strain 101 mice and (C3H × 101)F₁ hybrids.

The proximal tibial metaphysis of apparently healthy strain 101 mice, 3-4 weeks old, and (C3H×101)F1 hybrids, 3-48 weeks old, was studied by electron microscopy. Budding, immature, and mature C-type virus particles were found within trabecular bone tissue of 3 of 8 strain 101 and 4 of 12 (C3H×101)F1 mice. The particles were most common in lacunae of aging osteocytes and were only occasionally associated with osteoblasts. Although the morphology of budding and immature particles appeared to be identical with that of typical C-type viruses, most of the mature forms of particles showed atypical structure and size. The electron-dense core was very large and not clearly defined, measuring approximately 70-130 nm in diameter. This diffuse core sometimes completely filled the space within the envelope of the particles. The diameters of the pleomorphic mature C-type particles ranged from approximately 90 to 150 nm. The possible association between the production of pleomorphic C-type virus particles by bone cells and spontaneous osteomagenesis in 101 and (C3H × 101)F1 mice is discussed

Retroviral particles in radionuclide-induced murine osteosarcomas: mouse strain-related differences.

Twenty-six osteosarcomas from strain NMRI mice and twenty-six osteosarcomas from (C3H x 101)F1 hybrid mice were investigated by electron microscopy for the presence of retroviral particles. The bone tumors had been induced by the incorporation of the short-lived bone-seeking radionuclides 224Ra, 223Ra, or 227Th. All of the 26 osteosarcomas from NMRI mice contained retrovirus-like intracisternal type A particles in varying quantities. No type C retrovirus particles could be detected. In contrast, most of the 26 osteosarcomas from (C3H x 101)F1 mice contained budding, immature, and mature type C virus particles predominantly in large quantities. Intracisternal type A particles were also present in all tumors from these mice, but were found only occasionally after extensive search. The mouse strain-related differences in the presence of intracisternal type A particles and type C virus particles in the bone tumors do not provide evidence of an etiological relation of these particles to radionuclide-induced osteosarcomagenesis. Some of the mature type C virus particles observed in osteosarcoma tissue from the hybrid mice were atypical in structure and size. Such pleomorphic particles are probably associated with the spontaneous osteomagenesis which occurs in untreated old (C3H x 101)F1 mice

Virusähnliche Partikel in Ra-224-induzierten Osteosarkomen der Maus.

Electron microscopic investigation of osteosarcomas from 3 mice, induced by the incorporation of 224Ra, and an osteosarcoma metastasis from the liver of one of the animals revealed peculiar intracellular particles in all of the tumors. The particles were spherical, measured about 80 nm in diameter and consisted of 2 electron dense, ring shaped, membrane like shells which concentrically surrounded an electron lucent core. Nearly all of the particles with this doughnut like ultrastructural appearance occurred in cisternae of the rough surfaced endoplasmic reticulum (RER) of tumor cells. They were seldom observed in intracytoplasmic smooth surfaced vacuoles or located freely in the cytoplasmic matrix. Crescent shaped particles were occasionally found, presumably in the stage of formation by budding into cisternae of the RER from its membrane component. The ultrastructure, size and formation of particles, as well as their location in relation to intracellular structures, are similar to those described for type A viral particles. The significance of the virus like particles, especially in relation to the pathogenesis of the malignant bone tumors, is not known

Intracristale lineare Einschlüsse in Mitochondrien menschlicher Rhabdomyomzellen.

Electron microscopic study of a rhabdomyoma of the soft palate of a 50-year-old woman revealed linear structures within the intracristal spaces of mitochondria. In the center of most cristae, an electron-dense line was found located in parallel arrangement to the limiting cristal membrane. The linear inclusion was separated from the cristal membrane by a narrow space of lower electron-density. Thus, when sectioned longitudinally, the abnormal cristae exhibited a pentalaminar appearance. Additionally, they were characterized by a greater diameter than that of normal cristae and a 'rigid' configuration. Higher magnification showed that the intracristal line consisted of a row of periodically arranged, electron-dense dots. Sometimes, these seemed to be connected with the wall of the intracristal space by fine, electron-dense cross-striations. In some mitochondria of rhabdomyoma cells, crystals with a linear substructure were observed in both intra- and extracristal spaces. The crystalline bodies located within cristae had probably been formed by accumulation of linear inclusions. The extracristal bodies seemed to have arisen from fusion of pentalaminar cristae. It is supposed that the intracristal linear inclusions in mitochondria of rhabdomyoma cells represent crystallized proteins of mitochrondrial enzymes

Frühe Ultrastrukturveränderungen an den Skeletmuskelcapillaren der Ratte nach lokaler Röntgenbestrahlung.

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An unusual form of endoplasmic reticulum in mononuclear cells of a giant cell tumor of bone.

A peculiar configuration of endoplasmic reticulum (ER) was observed by electron microscopy in some mononuclear cells from a malignant giant cell tumor of bone that had been removed from a cervical vertebral body in a 54-year-old female. The unusual ER consisted of looped, smooth tubules, which originated from poorly developed rough ER present in the tumor cells. The tubular structures were approximately 23 ran in diameter and contained paracrystalline material. The curvilinear tubular ER closely resembles the vermiform tubular structures that have been observed mainly in histiocytes from different clinical forms of histiocytosis X