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Query: UMLS:C0276640 (TEM)
 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ultrastructural appearances of 7 primitive neuroepithelial tumours (PNETs) originating in soft tissues and bone are described. Three of the tumours represented primary soft tissue lesions, while locally recurrent tumour or pulmonary metastases were studied from the 4 skeletal tumours, all of which had been diagnosed previously as Ewing's sarcomas. Rosettes were present in one of the soft tissue lesions and although not seen in the primary skeletal neoplasms, they were identified by light microscopy (LM) in 2 of 3 pulmonary metastases, one of which had the morphology of a neuroepithelioma, with innumerable Homer Wright rosettes. Conventional TEM revealed cytoplasmic processes in all cases and rosettes in varying stages of development were also evident, but the appearances did not achieve the level of cellular organization seen in neuroblastoma: microtubules were few, while dense-core granules varied in number but were generally sparse and pleomorphic, resembling lysosomes. However, typical neurosecretory granules were found in one lung metastasis; the neoplastic cells comprising the same tumour also had epithelial markers in the form of well constructed desmosomes, while freeze-fracture analysis demonstrated elaborate tight junctions. In thin sections, junctions in the other tumours appeared rudimentary, but freeze-fracture of a further case revealed small collections of membrane particles suggesting extremely poorly developed desmosomes. Immunocytochemical study of 4 tumours (2 originating in soft tissue and 2 in bone) demonstrated weak to moderate immunostaining for neurone-specific enolase and with several monoclonal antibodies reactive with neuroblastomas, but there was no evidence of immunolabelling for tyrosine hydroxylase.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Primitive neuroepithelial tumours of soft tissues and of bone: further ultrastructural and immunocytochemical clarification of 'Ewing's sarcoma', including freeze-fracture analysis. 264 32

The aim of this study was to analyze the clinico-pathological and immunohistochemical features of 62 cases of odontogenic myxoma (OM) diagnosed in three Oral Pathology Diagnostic Services in Latin America, as well as to describe the ultrastructural features of three of these cases. OM showed a wide age range (9-71 years), with a mean of 27.97 yr (SD: 11.01) and a male to female ratio of 1:2.2. Mandible was affected in 37 cases (59.6%) and maxilla in 25 (40.4%), with 61.3% located in the posterior region. Thirty-nine cases (62.9%) were multilocular and 23 (37.1%) unilocular. Size ranged from 1 to 13 cm, (mean: 5.2 cm). Thirty-seven multilocular (54.8%) and 6 unilocular lesions (26%) were larger than 4 cm (p<0.05). Epithelial islands were identified in 5 cases (8%) on H&E stained sections, but AE1/AE3 and CK14 disclosed these structures in 15 cases each (24.2%); CK5 was positive in 8 (12.9%); CK7 in 2 (3.2%) and CK19 in only 3 cases (4.8%). All cases were negative for CKs 8 and 18, S-100 protein, NSE and CD68, and showed a low index of expression of Bcl2 and ki-67 proteins (<1%). Mast cell antibodies showed these cells in 45 cases (72.6%). Myofibroblastic differentiation evidenced by myofilaments and fibronexi was found in one case out of the three studied by TEM and 29 cases (46.7%) were positive by immunohistochemistry for alpha actin. In conclusion, only a minority of OM had epithelial islands, and only 3 cases expressed CK 19, indicating an odontogenic epithelium origin. Immunohistochemical and ultrastructural findings suggest that OM is a mesenchymal neoplasm in which several factors may contribute to its pathogenesis, including myofibroblastic differentiation and the participation of mast cell products. However, further investigations are needed to better understand the participation of these elements in this particular neoplasm.
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PMID:Odontogenic myxoma: clinico-pathological, immunohistochemical and ultrastructural findings of a multicentric series. 1799 87

Recently, pulmonary DC deserved the attention of researchers and clinicians as it was implicated in many diseases afflicting human lungs. However, there are no available data about the morphological or functional features of pulmonary dendritic cells in fetal or early neonatal life. The present study aimed to demonstrate the morphological development of DCs using light-, electron-microscopy, and immunohistochemistry. DCs showed strong immunoreactivity for both CD8 and CD56. Moreover, DCs strongly expressed CD34, VEGF, NSE, and connexin-43 within the developing pulmonary tissue. By SEM, DCs were polyhedral in shape with short cell processes in fetal life. By the advancement of the age, DCs became more numerous and exhibited rounded to oval cell bodies with many fine dendrites. TEM revealed that at early fetal life, DCs were characterized by their heterochromatic indented nuclei, few cell processes and few organelles. With the advancement of age, DCs showed dendrite-like processes and displayed signs of high endocytic activities with releasing of secretory materials. At late fetal life, DCs showed an obvious increase in the nuclear/cytoplasmic ratio and they exhibited a unique connection with type II pneumocytes and pulmonary endothelium by gap junction. In the early neonate, the DCs cells were seen in association with T-lymphocytes, neutrophils, telocytes (TCs), and air-blood barrier. They possessed many fine dendrites, the characteristic Birbeck granules and many vesicles. DCs may contribute to apoptosis, endocytosis, and angiogenesis. The difference in the maturation status may reflect different roles for DCs in the lung. The immature DCs may have an antigen-uptake role through endocytosis, while mature DCs may involve in antigen presentation to T-cells.
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PMID:Morphological characteristic and functional dependencies of dendritic cell in developing rabbit lung during fetal and neonatal life. 3123 38