SUMMARYSpontaneous osteomas in strain 101 mice, a strain which has a high incidence of benign bone tumours, harbour numerous C-type virus-like particles with pleomorphic characteristics. A cell-free extract from osteomas from two mice induced bone tumours, together with osteopetrosis and lymphomas, in newborn mice of the low incidence NMRI strain after a latent period of 12 to 15 months. When C3H embryo fibroblasts were infected with the osteoma extract, the resulting cell line produced virus (OA MuLVc) with a high titre. OA MuLV c was cloned by serial endpoint dilution and NIH 3T3 cells were productively infected. The resulting virus was named OA MuLVN. OA MuLV c and OA MuLVN also induced bone tumours, osteopetrosis and lymphomas 12 to 15 months after injection into newborn NMRI mice. The isolated virus showed typical characteristics of the murine retrovirus group. Fv-1 host range restriction assays classified the viruses as N-ecotropic and XC-positive. Tryptic p30 peptide analysis and RNase T1 fingerprint analysis of OA MuLVc and OA MuLVy indicated that OA MuLVc contains an Akv-like virus as well as additional components, whereas OA MuLVN is closely related to Akv, but not identical to it. Serological analysis of the envelope proteins using monoclonal antibodies also showed the virus to be similar, but not identical, to Akv virus.

Eight cell lines were established from murine osteosarcomas induced in vivo with the radionuclides 224Ra and 227Th. They have been compared by light and electron microscopy, by karyology, and by their growth properties. The morphology, the growth pattern, and the ability to induce tumors in mice indicate that five of them are tumor cell lines. Chromosome studies demonstrated that the five cell lines have marker chromosomes. The other cell lines only showed some criteria generally used to score for transformation of fibroblasts and they may be derived from stromal cells. All cell lines release virus particles in the culture fluid which have the typical properties of RNA tumor viruses. They possess C-type morphology, a density of 1.16--1.18 g/cm3, a 60--70 S RNA, a RNA dependent DNA polymerase and they induce syncytia in rat XC cells. The possible significance of these virus particles in radiation osteosarcomagenesis is discussed.

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 structures measured about 280-570 min 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.

Biopsied tissue specimens from 40 cases of classic, atypical classic, endemic, and AIDS-associated Kaposi's sarcoma (KS) were investigated by electron microscopy. To search for ultrastructural differences between non-AIDS-associated KS and AIDS-associated KS, the occurrence of the following 2 ultrastructural abnormalities of the rough-surfaced endoplasmic reticulum in KS cells was evaluated semi-quantitatively: tubuloreticular structures (TRS) and intracisternal paracrystalline inclusions (IPI). These peculiar structures were found in 23 of the 40 KS cases. Two types of TRS could be distinguished: loose TRS (LTRS) and compact ones (CTRS). LTRS were observed in endothelial cells of tissue from all the different epidemiological types of KS. CTRS were confined to AIDS-associated KS. IPI were present in endothelial tumor cells of only 3 non-AIDS-associated KS cases. The study shows that in cells of KS tissue only CTRS, but not LTRS, are an ultrastructural marker for AIDS-associated KS.

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Weibel-Palade bodies in Kaposi's sarcoma cells Russell Jones et al recently reported immunohistochemical findings which favour the hypothesis that Kaposi's sarcoma cells are derived from lymphatic endothelium.'

The clinical manifestations of primary or idiopathic hemochromatosis include mainly hepatomegaly, diabetes mellitus, and hypogonadism. Most investigators postulated that the hypogonadism is caused by pituitary dysfunction and that the deposition of iron in the testes is of little importance. We found not only pituitary failure in a 45-year-old man with idiopathic hemochromatosis (low LH and FSH levels, no response to GnRH) but could also detect by light microscopy deposition of iron in capillary endothelial cells and in the perivascular space of the testicular tissue. Electron microscopic study of tissue from the testes showed intracytoplasmic hemosiderin deposits in capillary endothelial cells. Abundant lipofuscin granules were present in Sertoli cells and Leydig cells. The serum testosterone levels were low and there was no response in the HCG test. The intratesticular testosterone levels were also lowered. In our opinion, the androgenic deficiency in idiopathic hemochromatosis is not only caused by pituitary failure but also by testicular dysfunction due to deposits of hemosiderin and lipofuscin in the testes. ldiopathische Harnochromatose bei einem 45jahrigen unfruchtbaren MannZusammenfassung: Die klinischen Manifestationen der primaren oder idiopathischen Hamochromatose sind hauptsachlich Hepatomegalie, Diabetes mellitus und Hypogonadismus. Die meisten Untersucher nehmen an, dai3 der Hypogonadismus durch eine Storung der Hypophysenfunktion bedingt ist , und daB Eisenablagerungen in den Hoden von untergeordneter Bedeutung sind. Wir fiiden bei einem 45 Jahre alten Mann mit idiopathischer Hamochromatose nicht nur eine Hypophysenfehlfunktion (niedrige LH-und FSH-Werte, kein Ansprechen auf GnRH), sondern konnen auch lichtmikroskopisch Eisenablagerungen in Kapillarendothelzellen und im Perivaskularraum des Hodengewebes nachweisen. Die elektronenmikroskopische Untersuchung von Hodengewebsproben zeigt intrazytoplasmatische Hamosiderinablagerungen in Kapillarendothelzellen. In Sertoli-und in Leydigzellen sind massenhaft Lipofuszingranula vorhanden. Die Serum-Testosteronwerte sind erniedrigt und zeigen keinen Anstieg im HCG-Test. Auch die intratestikularen Testosteronwerte sind erniedrigt. Nach unserer Meinung ist das Androgendefiiit bei der idiopathischen Hamochromatose nicht nur auf eine Hypophysenfehlfunktion, sondem auch auf eine Funktionsstorung der Hoden durch dort abgelagertes Hamosiderin und Lipofuszin zuriickzufiihren.

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.