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I Dardick

Publications and source records attributed to I Dardick.

At least 145 records · Page 8Linked to original sources
PubMed1976

Cellular composition of erythropoietic cell populations and aggregate cell cultures derived from early chick blastodiscs.

Light and electron microscopy of suspensions of cells prepared by dispersing chick blastodiscs at primitive-streak and head-fold stages showed the presence of numerous yolk granules, yolk-rich endodermal cells and occasional presumed ecto- and mesodermal cells. Several cell fractions prepared from this suspension by sedimentation through discontinuous Ficoll gradients were of similar composition. No enrichment of any particular cell type which might account for either differential sedimentation or erythropoietic potential of the fractions could be recognized. Two fractions, EP 1, and EP 2, were cultured as cell aggregates on vitelline membranes. EP 1 produced highly organized blood islands containing developing erythrocyte cells, organized endothelium, fibroblasts, thrombocytes and occasional granulocytes. Blood islands derived from EP 2, on the other hand, contained essentially only aggregates of erythroblasts embedded in endoderm. It is tentatively suggested that EP1 contains young multipotential hematopoietic precursors while EP 2 has only older blood-cell precursors committed to erythrocyte development. No cellular basis for the resolution of EP 1 into two complementary subfractions could be recognized.

Animals↗
PubMedDate not supplied

Ultrastructural contributions to the study of morphological differentiation in malignant mixed (pleomorphic) tumors of salivary gland.

Ultrastructural studies of pleomorphic adenoma have shown a coordinated differentiation of luminal epithelial and modified myoepithelial cells with the latter cells related to processes resulting in the myxochondroid stroma. Five examples of various histologic types of malignant mixed tumor of parotid origin were examined by electron microscopy to see if underlying patterns of tumor cell differentiation and organization matched those of pleomorphic adenoma. Whether they were intracapsular tumors (with or without identifiable pleomorphic adenoma), carcinomas ex pleomorphic adenoma, or a true malignant mixed tumor, all lesions had cell types and organizations either identical to those in pleomorphic adenoma or, as in less-differentiated examples, displayed features suggesting origin from luminal cells, myoepithelial cells, or both. Even the chondroid cells in the true malignant mixed tumor expressed ultrastructural features indicating their epithelial derivation. On the basis of these findings, some alterations to the classification and terminology of the subtypes of malignant mixed tumor are suggested.

Adenoma, Pleomorphic↗
PubMedDate not supplied

Myoepithelial cells in salivary gland tumors--revisited.

It is an interesting parallel that the myoepithelial cell with its hybrid epithelial and mesenchymal structural and functional phenotype has a dual role in such salivary gland tumors as pleomorphic adenoma. This cell is responsible for considerable proportions of the epithelial component of this tumor, including squamous metaplasia, and is also the agent principally involved in the synthesis, organization, and cytologic modifications of the chondromyxoid regions. Neoplastically modified myoepithelial cells are also generally accepted to be a significant component of salivary gland tumors such as epithelial-myoepithelial carcinoma, certain adenocarcinomas, and, of course, myoepitheliomas. The range of myoepithelial cell alterations can be appreciated via ultrastructural assessment of the above four classes of salivary gland tumors. An electron microscopic survey of monomorphic adenomas, adenoid cystic carcinomas, and mucoepidermoid carcinomas reveals some having a tumor cell component with structural modifications and localization similar to the modified myoepithelial cells in pleomorphic adenomas and the adenocarcinomas noted above. Such ultrastructural findings have important implications for clarifying diagnostic problems, for understanding histogenetic relationships, and for improving the classification of salivary gland tumors.

Adenocarcinoma↗
PubMedDate not supplied

Basal cell adenoma with myoepithelial cell-derived "stroma": a new major salivary gland tumor entity.

The light microscopic, immunohistochemical, and ultrastructural features of a unique variant of tubular-trabecular basal cell adenoma are described. The unusual feature of the six examples reported is the richly cellular "stroma" composed of spindle cells coursing between the anastomosing cords of epithelial tumor cells. Immunohistochemistry of all six cases and electron microscopy of two examples illustrated the biphasic differentiation of the epithelial portion of this form of basal cell adenoma, with a central core of duct luminal cells bordered on either side by one or more layers of modified myoepithelial cells. By light microscopy, the features and arrangement of cells in "stromal" regions of this tumor convey a fibroblastic derivation. However, this population of cells stains strongly for S-100 protein, ultrastructurally displays excessive external lamina production, intercellular junctions, and a growth pattern unlike fibroblasts, and is involved in the formation of extracellular mucinous materials. Such aspects indicate a second population of neoplastic myoepithelial cells in this tumor. Thus, this form of tubular-trabecular basal cell adenoma displays tricellular differentiation and, perhaps, may be considered either a hybrid basal cell adenoma and myoepithelioma or a cellular pleomorphic adenoma.

Adenoma↗
PubMedDate not supplied

Characterization of epimyoepithelial islands in benign lymphoepithelial lesions of major salivary gland: an immunohistochemical and ultrastructural study.

Knowledge of the processes leading to the development of epimyoepithelial islands bears on histogenetic and morphogentic processes in salivary gland tumors. Immunohistochemical and ultrastructural investigations of the cellular composition of epimyoepithelial islands were carried out on three examples of benign lymphoepithelial lesions with varying histologic features. The monoclonal anti-keratin antibody 312C8-1, which specifically decorates myoepithelial cells of the normal salivary gland, also stains the myoepithelial cells surrounding residual acini and intercalated ducts in benign lymphoepithelial lesions and the cell population of epimyoepithelial islands, with the exception of persisting luminal epithelial cells. Ultrastructurally, the myoepithelial cells of involuting acini and ducts and the modified myoepithelial cells of epimyoepithelial islands, identified in both locations by the monoclonal antibody 312C8-1, show an increasing complement of tonofilament bundles. In addition, persisting lumens (often distended with lymphocytes) and definite luminal epithelial cells can be seen in electron micrographs of some epimyoepithelial islands. The designation for this characteristic epithelial feature of benign lymphoepithelial lesions is therefore appropriate.

Humans↗
PubMedDate not supplied

Signet-ring cell variant of large cell lymphoma.

A diffuse, large cell lymphoma of palatine tonsil was found to contain a considerable number of enlarged tumor cells with prominent, hyaline, Russell body-type cytoplasmic inclusions displacing the nucleus peripherally and, thus, the morphologic features of signet-ring cell lymphoma. Immunoperoxidase staining revealed that the contents of the signet-ring cells were strongly positive for mu heavy chains and kappa light chains. Ultrastructurally, Russell body-type inclusions consisted of multiple, angulated, electron-dense crystalloids enclosed within expanded segments of rough endoplasmic reticulum.

Humans↗
PubMedDate not supplied

Ultrastructural morphometric study of follicular center lymphocytes: I. Nuclear characteristics and the Lukes-Collins' concept.

A combined ultrastructural and morphometric image analysis study was carried out on the nuclear profiles of follicular center and mantle zone lymphocytes of six cases of reactive hyperplasia in human lymph node biopsies. For accuracy of morphological observations and sampling at low magnifications, sections were mounted on formvar-covered slot grids. Measurements of nuclear profile features of small (untransformed) lymphocytes in mantle zones served as the standard for a supposed unimodal population in each case. Analysis of nuclear profile area values indicated that during lymphocyte transformation in follicular centers nuclei had a gradual and progressive increase in size and that the sampled nuclear profiles in both the mantle zone and follicular center were unimodal. Lymphocyte nuclear shape (contour index) was a more complex, and likely biologically independent, feature than nuclear area in both the mantle zone and follicular center. Nuclear profile contour indexes of mantle zone lymphocytes were more irregular than suspected and in some cases had mean values greater than those of follicular center lymphocytes. Furthermore, the frequency distribution of nuclear contour index was not normally distributed in either the follicular center or mantle zone due to the presence of a small proportion of highly irregularly shaped nuclear profiles in both sites. The results indicated that some premises of existing concepts of follicular center cells and the process of lymphocyte transformation in follicular centers were incorrect and should not be directly extrapolated to the nuclear profile characteristics in non-Hodgkin's lymphoma.

Cell Nucleus↗
PubMedDate not supplied

Ultrastructural morphometric study of follicular center lymphocytes: II. Analyses of cleaved-cell populations do not support the Lukes-Collins' concept.

Ultrastructural morphometric analysis was carried out on six cases of lymph node biopsies with reactive hyperplasia to establish the frequency and depth of invaginations in nuclear profiles situated in the mantle zones and follicular centers. The frequency distribution of the depth of invaginations was similar in nuclear profiles whether in the small lymphocytes of mantle zones or the small, partially transformed (centrocytes) and fully transformed (centroblasts) lymphocytes of follicular centers. Invaginated and cleaved lymphocytes were not confined to the partially transformed (centrocytic) lymphocytes of follicular centers, and nuclear profiles with invaginations bore no resemblance to those depicted in the Lukes-Collins model. A considerable proportion of mantle zone lymphocyte nuclear profiles had invaginations (ranging from 7.5% to 53.6%) and there was no difference between the frequency of deep indentations or clefts in mantle zone lymphocytes (8.1 +/- 5.4%) and the small unstimulated (9.3 +/- 5.3%) and partially transformed (8.4 +/- 1.4%) lymphocytes in follicular centers. Computer modeling of stylized nuclei with conical indentations indicated that all lymphocytic nuclei likely have multiple invaginations or groove-like creases.

Cell Nucleus↗
PubMedDate not supplied

Ultrastructural spectrum of hemangiopericytoma: a comparative study of fetal, adult, and neoplastic pericytes.

Since ultrastructural examination is often employed to assess controversial soft tissue tumors, it is important to be aware of the range of differentiation assumed by the tumor cells in hemangiopericytomas. For this purpose, 35 examples (10 localized to the central nervous system and 25 located peripherally) were examined ultrastructurally, and, of these, 20 cases were also studied immunohistochemically for the presence of intermediate filaments and muscle-specific actin. Based on cytologic characteristics evident by electron microscopy, tumor cell differentiation was classed as pericytic (32%), myoid (8%), nondescript (48%), fibroblastic (4%), and histiocytic (8%). Vimentin was the only intermediate filament expressed in the normal pericytes of human fetal and adult tissues and in the neoplastic pericytes of all of the hemangiopericytomas. Muscle-specific actin was present in normal pericytes, but only focally in two of the hemangiopericytomas. In various combinations basal lamina-like materials, cytoplasmic processes, cytoplasmic filaments, discrete basal lamina, and poorly formed intercellular junctions were the most frequently noted features of the tumor cells in hemangiopericytomas, whether central or peripheral, and they assist, along with the organizational relationship of tumor cells and capillaries, in distinguishing this lesion from other soft tissue sarcomas.

Actins↗
PubMedDate not supplied

Myoepithelioma--new concepts of histology and classification: a light and electron microscopic study.

Based on histological, immunohistochemical, and ultrastructural studies, it is now apparent that the modified myoepithelial cell component of pleomorphic adenomas has a considerable range of cytological features. We reasoned that myoepitheliomas could be tumors with a similar spectrum of neoplastic myoepithelium but lacking the ductal element displayed in pleomorphic adenomas. A review of available salivary gland tumors identified 40 examples based on this definition. Architecturally, these myoepitheliomas displayed either nonmyxoid (solid), myxoid (pleomorphic adenoma-like), reticular (canalicularlike), or mixed growth patterns, while cytologically the lesions were composed of spindle-type (32.5%), hyaline-type (7.5%), epithelial-type (45.0%), clear-type (2.5%), or mixed-type (12.5%) tumor cells. Electron microscopy was carried out on eight examples and detailed immunohistochemistry on two methanol-fixed cases. As a result of the current review of myoepitheliomas and the description of similar lesions in the literature, it is our contention that salivary gland myoepitheliomas are not as rare as has been purported.

Humans↗
PubMedDate not supplied

"Anemone" cell (villiform) tumor of the brain.

At age 31, the patient developed hydrocephalus secondary to a brain lesion that had been present for 12 years. A ventriculoperitoneal shunt was performed, but a stereotactic biopsy did not establish a definitive diagnosis at that time. At age 34 the patient experienced spontaneous intratumoral and ventricular hemorrhage, which prompted radical surgical resection of the lesion. Histologic and immunocytochemical findings established a diagnosis of ependymoma; review of the ultrastructure of the tumor from the biopsy performed when the patient was 31 years old revealed the characteristics of an "anemone" cell neoplasm.

Adult↗
PubMedDate not supplied

A quantitative comparison of light and electron microscopic diagnoses in specimens obtained by fine-needle aspiration biopsy.

Because fine-needle aspiration biopsy (FNAB) is being increasingly used as a primary diagnostic tool, it is essential to obtain the maximum information from the aspirate. Electron microscopy is an adjunctive procedure that is readily applied to FNAB specimens. The value of electron microscopy to the cytopathologist was assessed by comparing the initial, tentative, or interim diagnosis based on light microscopic features with the diagnosis resulting from the ultrastructural characteristics of needle rinse material. Over a 3-year period, 279 FNAB specimens obtained under radiologic control were examined ultrastructurally; of these, 57 (20.4%) were considered inadequate specimens for diagnostic purposes. The remaining 222 FNAB specimens were segregated into four groups: 17 cases (7.7%) in which electron microscopy played a major role because the final diagnosis was unsuspected from light microscopy; 43 cases (19.4%) in which electron microscopy selected a specific diagnosis from a set of differential diagnoses or provided additional information that was clinically relevant; 45 cases (20.3%) in which additional diagnostic information was obtained by electron microscopy but was not clinically relevant; and 117 cases (52.6%) in which electron microscopy was not helpful because the light and electron microscopic diagnoses were the same. In this comparative study, electron microscopy provided a major contribution to the final cytologic diagnosis in 27.1% of the cases (groups 1 and 2). Descriptive examples illustrate how the architectural and cytologic features revealed by electron microscopy assist in establishing the final diagnosis. Examination of needle rinse specimens, particularly aspirates from lung and liver, indicates that most FNABs provide mini-surgical biopsy specimens that are well suited to ultrastructural examination.

Adult↗
PubMedDate not supplied

Filamentous inclusions of unusual composition and architecture in a metastatic tumor showing myoepithelial differentiation.

A hyaline/eosinophilic cytoplasmic inclusion is described in a metastatic tumor occurring in the omentum and bowel of a 32-year-old white woman. The tumor was essentially of round cell type; was positive for cytokeratin, actin, and S-100 protein by immunohistochemistry; and showed desmosomes (maculae adherentes), tonofibrils, modestly developed myofilaments with focal densities, and a basal lamina by electron microscopy. It was therefore interpreted as showing myoepithelial differentiation. Nearly all cells possessed a large, rounded cytoplasmic inclusion that was architecturally unusual, consisting of intermediate filaments intermingled with lattices of fine filaments. The inclusions exhibited an additionally unusual immunohistochemical staining for both cytokeratin and actin. A comparison with cases described in the literature is made.

Adult↗
PubMedDate not supplied

Osteogenic sarcoma with epithelial differentiation.

This case report details an osteogenic sarcoma arising in a vertebra in which cytokeratin intermediate filaments were detected immunohistochemically with three different antibodies. This feature was present not only in the primary neoplasm but also in two local recurrences and a metastasis to the iliac bone. What is unique about this primary bone tumor, however, is the structural evidence for epithelial differentiation. Ultrastructurally, well-formed desmosomes and tonofilaments were present in all four surgically resected specimens. This tumor expands the list of soft tissue and bone tumors in which anomalous expression of intermediate filaments can occur but, more important, illustrates that changes in genetic expression of neoplasia of mesenchymal origin can result in paradoxic epithelial differentiation.

Adult↗
PubMedDate not supplied

Immunogold localization of actin and cytokeratin filaments in myoepithelium of human parotid salivary gland.

Myoepithelial cells of salivary gland are uniquely specialized cells; their function is unclear, but the considerable complement of muscle-specific actin suggests contractility is one function. By routine transmission electron microscopy myofilament visualization is variable. Some myoepithelial cells appear to have limited and only focal aggregates of myofilaments, while others seem to have readily appreciated myofilaments within a longitudinally oriented cytoplasmic zone at the basal portion of the cell. However, immunogold electron microscopy using the anti-muscle-specific actin antibody, HHF35, while indicating a basal distribution for the muscle-isoform of actin in a platelike fashion in certain myoepithelial cells, also reveals that others associated with both intercalated ducts and acini have a more generalized distribution of myofilaments throughout the cytoplasm. Actin was also noted within tonofilaments and double immunogold labeling using both the HHF35 and AE1/AE3 (anticytokeratins) antibodies confirmed the variable interrelationship of these two filaments. Within any one myoepithelial cell, actin and cytokeratins might colocalize in some areas of the cytoplasm containing filaments, but not in adjacent zones. These results suggest that intermediate filaments and myofilaments are complexly organized in myoepithelial cells, and that quantitative and qualitative differences exist in the expression and distribution of intermediate filaments and myofilaments. These cells are likely structurally, if not functionally, heterogeneous.

Actins↗