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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzymes involved in conversion of pregnenolone to testosterone in Leydig cell tumors showed a wide distribution among smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER), and cytosol, while these enzymatic activities in normal testes were associated primarily with smooth endoplasmic reticulum. Progesterone, used as a substrate in the presence of an NADPH-generating system, was metabolized to androstenedione and finally to testosterone by microsomes from some strains of tumor which did not form testosterone from exogenous labeled androstenedione. Treatment of microsomal membranes from normal testes with 0.1 M Ca++ and Mg++ caused a marked decrease in 17 beta-dehydrogenase activity, measured as conversion of exogenous [3H]androstenedione to [3H]-testosterone, without serious effects on activities of 3 beta-ol-dehydrogenase or 17 alpha-hydroxylase. Studies of initial velocity kinetics showed that treatment with magnesium ion resulted in a marked reduction in affinity of androstenedione for 17 beta-dehydrogenase while the maximum velocity was the same as in untreated microsomes. Also, experiments using [14C]progesterone and [3H]androstenedione simultaneously as substrates demonstrated that treatment with Mg++ ion made it more difficult for exogenous [3H]androstenedione to reach the active site of 17 beta-ol-dehydrogenase than [14C]androstenedione formed in the microsomal membrane from [14C]progesterone. Microsomal proteins were more easily solubilized and 3 beta-ol-dehydrogenase was more severely influenced by Mg++ ion in tumor membranes than in normal microsomes.
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PMID:The possible roles of membrane organization in the activity of androgen biosynthetic enzymes associated with normal or tumorous mouse Leydig cell microsomes. 3 99

To establish the cell type responsible for the production of estrogens in an ovarian tumor, seven thecomas, three granulosa cell tumors and one fibroma were studied with electron microscopy. The secretion of estrogens by the tumor was determined by measuring the plasma levels of estrogens in the ovarian and cubital veins of some patients and examining the histology of the endometria. Polygonal cells with abundant smooth endoplasmic reticulum (SER) at the ultrastructural level were found in the tumors of patients with clinical signs of hyperestrogenism. It is likely that these cells are the site of steroidogenesis, which is known to be reflected by SER in the cells of the human corpus luteum.
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PMID:An ultrastructural and clinical study of theca and granulosa cell tumors. 4 72

Light and electron microscopical examination of a pituitary adenoma showed that the tumor was composed of prolactin cells that produced amyloid-like material. The findings have been interpreted in favor of the role of rough endoplasmic reticulum in amyloid fibril formation within the adenoma cells. Histochemical and fine structural data indicate that the material produced by this tumor resembles apudamyloid rather than immunoamyloid.
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PMID:Pituitary adenoma producing amyloid-like substance. 5 61

The reversibility of changes in ultrastructure, K+, and ATP content was studied in experimental injury of Ehrlich ascites tumor cells. Different grades of injury resulted from incubations in N2 atmosphere and omitting substrate after which air and glucose were reinstated. The changes observed in cells after 1 hour of anoxia such as dilations of endoplasmic reticulum, complex invaginations of plasma membrane, and slight condensation of mitochondria, as well as a drop of K+ and ATP content to a level approximating 40 per cent of the paired controls, were entirely reversible. After 2 hours of anoxia approximately 50 per cent of the cells recovered, but after 3 and 4 hour of anoxia most of the cells were irreversibly damaged showing markedly swollen mitochondria with flocculent densities.
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PMID:Studies of cellular recovery from injury. I. Recovery from anoxia in Ehrlich ascites tumor cells. 5 20

An immunocytochemical and ultrastructural study using the Fab fragment of an anti-human Ig antibody labelled with peroxidase was carried out on affected lymph nodes from five Hodgkin's disease patients. The tumor cells (Reed-Sternberg cells and Hodgkin cells) showed an exclusively hyaloplasmic granular staining. By comparing these grains with ribisome staining. By comparing these grains with ribosome staining of the endoplasmic reticulum of plasma cells it could be suggested that they are free risobomes. This ribosomal Ig synthesis is a major argument for the B lymphocyte nature of Reed-Sternberg and Hodgkin cells. The total absence of vacuole staining allows us to conclude that these cells are not histiocytic or macrophage derivatives.
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PMID:Ultrastructural and immunocytochemical localization of immunoglobulin synthesis in tumor cells in Hodgkin's disease. 8 23

In addition to a light-microscopical and histochemical investigation of primary and metastic lesions in 27 cases of Ewing's sarcoma, biopsy materials from the primary bone lesions of 7 patients with this neoplasm were examined histochemically, enzyme-cytochemically and electron microscopically to elucidate the histogenesis and nature of the neoplasm. Ultrastructural observation has revealed that besides intracytoplasmic and extracellular deposition of glycogen the tumor cells possess several cytological features characterized by intracytoplasmic microfilaments of varying thickness up to 80 A, occasional appearance of dense patches, fat droplets, desmosomal connections and reminiscent attachment bodies. The tumor cells are mostly round, oval or polygonal in shape, but spindle or elongated cells are intermingled and occasionally contain well-developed rough endoplasmic reticulum, resembling pericytes or fibroblasts. In the intercellular spaces amongst the tumor cells, varying amounts of variable-shaped amorphous materials are found, which are compatible with acid mucopolysaccharides and glycoproteins histochemically verified. These findings may suggest that Ewing's sarcoma is a highly malignant neoplasm originating from a transitional cell developed from pericytes to vascular smooth muscle cells in the bone marrow.
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PMID:Cytological characterization and histogenesis of Ewing's sarcoma. 13 79

A case of abdominal wall epithelioid sarcoma, studied by light and electron microscopy over a 3-year period, is presented. Ultrastructurally, there appear to be two types of tumor cells, light and dark, which differ by virtue of a heavier concentration of microfibrils and dilated rough endoplasmic reticulum in the dark cells. Both tumor cell types contain prominent Golgi systems, abundant free ribosomes, and numerous pinocytotic vesicles. The ultrastructural characteristics of the tumor cells resembel those of epithelioid cells of experimental human granulomas, as well as those of normal human synovium. A multifaceted relationship between histiocytes and synovial cells is demonstrated and it is concluded that the tumor is probably derived from mesenchymal reserve cells capable of differentiating a long histiocytic or synovial lines. Preliminary chemotherapeutic data are reviewed.
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PMID:Epithelioid sarcoma: case report with ultrastructural review, histogenetic discussion, and chemotherapeutic data. 13 71

A pituitary adenoma with suprasellar extension that had caused hyperthyroidism due to secretion of excess thyrotropin (TSH), as well as mild hyperprolactinemia, was studied with differential staining, immunocytochemistry and electron microscopy. Most cells of the tumor strained lightly with aldehyde thionin, which demonstrates the granules of normal thyrotrops, and immunocytochemically with antiserum to the hormone-specific beta chain of TSH. A minority of the cells was immunoreactive for prolactin. Electron microscopy revealed light cells interspersed with highly pleomorphic dark cells. Both were sometimes multinucleated, and contained variable numbers of small secretion granules, multiple Golgi complexes, and abundant endoplasmic reticulum.
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PMID:Pituitary adenoma producing thyrotropin and prolactin. An immunocytochemical and electron microscopic study. 14 21

Annulate lamellae were observed in untreated in vivo ascites tumor cells with a diminished cytoplasmic microtubule complex. The ascites tumor cells in vitro responded to prolonged colchicine treatment with the formation of annulate lamellae. Simultaneous treatment with dibutyryl cycle adenosine monophosphate and colchicine seemed to enhance the formation of annulate lamellae. Single pore complexes were found in the granular endoplasmic reticulum in untreated tumor cell in vitro, and a close association of microtubules with the nuclear envelope was observed. Our results suggest the existence of an interrelationship between the cytoplasmic microtubule complex and certain other cell structures, i.e. the nuclear envelope, annulate lamellae, and single pore complexes.
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PMID:Interrelationship between annulate lamellae and the cytoplasmic microtubule complex in tumor cells in vivo and in vitro. 14 57

The cytology of 6 osteosarcomas was examined by electron microscopy. In keeping with the varied pattern of osteosarcomas seen by light microscopy several types of tumor cells could be differentiated: osteoblast-like, fibroblast-like, chondroblast-like, osteoclast-like and histiocyte-like cells. Moreover, atypical malignant mesenchymal cells and vascular spaces were present. The individual cytoplasmic organelles are not considered to be specific to particular types of cell as seen from the discussion of the significance of rough endoplasmic reticulum, microfilaments and lysosomes. Only examination of the composite pattern of subcellular organelles allows the differentiation of certain cell types. All tumor cells visible in osteosarcomas are considered as modifications of a transformed common progenitor cell. Because of the variegated cytological picture a multipotent mesenchymal cell rather than an osteoblastic cell is assumed to be the ancestor cell.
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PMID:Ultrastructural cytology of human osteosarcoma cells. 15 46


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