J.R. Rüttner

Ultrastructural Study of the Normal Rabbit Synovium

The major lining cells of normal rabbit synovium are morphologically classified into two types. One type resembling macrophages or histiocytes (M type) is characterized by dense peripheral nuclear chromatin, many cytoplasmic vacuoles, coated vesicles, poorly developed, rough-surfaced endoplasmic reticulum (RER) and numerous filopodia. Some of the superficially located M cells containing accumulated cytoplasmic filaments are small and less active than the lower M cells. The second type resembling fibroblasts (F type) possesses dispersed nuclear chromatin, distended RER, prominent Golgi apparatus and abundant smooth-surfaced pino-cytotic vesicles. Lysosomal inclusions are commonly seen in both types of cells. In view of the morphological and functional similarities of M cells and regular macrophages or histiocytes, respectively, it seems likely that they are derived from common precursors and these precursor cells differ from those of F cells.

Histochemical localization of acid glycosaminoglycans in human articular cartilage.

Fresh human articular cartilage from patients, 23 to 79 years of age, has been examined histochemically for its distribution of acid glycosaminoglycans. The alcian blue stain with different salt concentration enabled us to localize chondroi-tin sulfate and keratan sulfate in the matrix and in the halos. Young cartilage had a fairly even distribution of chondroitin sulfate, and only the matrix of the deepest zone stained less intensely. With increasing age the intensity of the chondroitin sulfate stain decreased and the tendency for a lack of matrix stain in the deeper layer was more pronounced in old than in young cartilage. In young cartilage, keratan sulfate is exclusively found in the matrix; the halos and their immediate surroundings are unstained. With increasing age and distance from the surface this pattern is less marked and keratan sulfate may be found even inside the halos. In the examined material four of the cartilages, here referred to as slightly arthrotic cartilage, showed an acid glycosaminoglycan distribution which differed from normal as well as from arthrotic cartilage. In these cases the chondroitin sulfate concentration was high in the halos while the matrix itself was unstained. The keratan sulfate distribution was even more deviating in showing an unstained matrix and a ring formation around the secondary halos in the upper half, and intensely stained halos in the lower half of the section.

Early Fibrogenicity of Asbestos Fibers in Visceral Peritoneum

Different asbestos types and milled asbestos cement were inoculated intraperitoneally into mice. Mesenteric tissue (appendices epiploicae) was examined by transmission electron microscopy at different intervals between 2 h and 3 weeks after exposure to asbestos. As early as 2 h after asbestos administration, the investigated tissues exhibited focal mesothelial cell loss barring the basement membrane, which at some points was even disrupted. Severe cell damage, obviously caused by the mineral fibers, was discernible in the remaining mesothelial cells. At a later stage, the whole peritoneal sheet underwent inflammatory and diffuse fibrotic processes. The early surface irritation is due to the mechanical influence of the penetrating asbestos fibers. The results confirm our previously published findings with the scanning electron microscope that asbestos has distinct fibrogenic properties.

Morphological Aspects of Interactions between Asbestos Fibers and Human Mesothelial Cell Cytoskeleton

The interaction of chrysotile and amphibole asbestos fibers with the cytoskeleton of cultured human mesothelial cells from nontumoral pleural effusions was studied using scanning electron and immunofluorescence microscopy. Asbestos-exposed mesothelial cells show a massive annular condensation of cytokeratin filaments, forming a concentric ring enveloping the nucleus and the phagocytosed asbestos fibers. By detergent extraction of the cells it could be shown that the asbestos fibers are in close contact with the nuclear membrane and associated with the cytoskeletal framework of the cells. An association of cytokeratin filaments with the asbestos could be observed during phagocytosis of the fibers. The disturbance of the cell cytoskeleton and the close morphologic contact between asbestos fibers and the nuclear membrane may have some relevance in explaining the well-recognized carcinogenic effects of asbestos mineral fibers.

Diffuse ‘Asbestosis-Like’ Interstitial Fibrosis of the Lung

A case of diffuse interstitial fibrosis of the lung resembling asbestosis is presented. Chemical, mineralogical and electron microscopical investigations revealed platy silicates but no asbestos. Mica

Silica Toxicity for Macrophages in vitro: a New Cytotoxicity Test

Soluble factors released from silica-damaged macrophages inhibit proliferation of various haematopoietic cells in long term cultures. The same holds true for damage induced by heat, non-physiological pH, freezing and thawing. This phenomenon is dose-dependent and correlates with the degree of macrophage viability. Thus, a base for measuring the amount of damage to the macrophage is established.

Giant platelets and fibrin-like inclusions in platelets of BALB/c mice after intraperitoneal inoculation of HIPA tumour agent

2 days after ip inoculation of cell-free extracts of HIPA tumour, giant platelets and platelets with band-like inclusions were found in blood of BALB/c mice. Band-like inclusions with platelets have morphologic structure of fibrin. Their presence in the thrombocytes is probably an accidental finding. Giant platelets in the circulating blood are probably due to a disturbed megacaryocytopoiesis. 2 Tage nach intraperitonealer Inoculation von zellfreiem Extrakt aus HIPA-TUMOR wurden Riesenthrombocyten und bandförmige Einschlüsse in den Thrombocyten aus peripherem Blut der BALB/c Maus gefunden. Solche Einschlüsse zeigen die morphologische Struktur von Fibrin. Die bandförmigen Einschlüsse erscheinen als ein zufälliger Befund, dagegen stellen wahrscheinlich die Riesenthrombocyten das Resultat einer gestörMegakaryocytopoese dar.

Interaction of Platelets with Ascitic Plasmacytoma in vitro

During interaction in vitro of syngenic platelets from healthy mice with HIPA ascitic plasmacytoma, clot formation was slower than during interaction of syngenic platelets from HIPA tumor-bearing mice with HIPA plasmacytoma. The platelet aggregates were composed, in both cases, of ‘balloon platelets’ and tumor cells. The granulated part of the ‘balloon platelets’ made up the centre, whereas granule-free spheroids were seen at the periphery of the aggregates. To contact with platelets, the tumor cells reacted with formation of microvilli, condensation of mitochondria and phagocytosis of the granule-free spheroids. No formation of pseudopodia by platelets in contact with the tumor cells was observed.

Loss of Protective Activity of BALB/c Spleen Homogenate against Cell-Free Transmission of HIPA-Plasmacytoma by Pretreatment with Mineral Oil of Spleen-Donor Mice

A significant loss of protective activity of BALB/c spleen homogenate against cell-free transmission of HIPA plasmacytoma was noted by pretreatment with mineral oil of spleen donor mice. No decrease of protection was found in ICR mice, when they received intraperitoneally spleen homogenate from oil-pre-treated BALB/c mice. A strain specific immunosuppression, combined with virus activation, could be the mechanism of this effect.

Knochenläsionen und Metastasierungsmuster in einem experimentellen Plasmozytom der BALB/C-Maus (HIPA-Tumor)

The distribution of the metastases of an experimentally produced plasmocytoma (HIPA-tumor) was determined after intravenous, subcutaneous or intraperitoneal inoculation of a defined number of ascites tumor cells into isologous mice. After a latent period of about 17 days following intravenous inoculation osteolytic and osteoplastic metastases were common. These lesions were verified roentgenographically, histologically, and by maceration of gross specimens of bone. Bone metastases were rare after subcutaneous inoculation of neoplastic cells. Pulmonary metastases were equally common after intravenous or subcutaneous inoculation. Intraperitoneal inoculation did not produce extraperitoneal metastases. Incidence and morphological appearance of bone metastases agreed with those of other known experimental plasmocytomas. In contrast to the latter, HIPA-tumor did not give rise to splenic or hepatic metastases. The special position of the HIPA-tumor among murine plasmocytomas was discussed.