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L H Rademakers

Publications and source records attributed to L H Rademakers.

At least 55 records · Page 3Linked to original sources
PubMed1988

Interfering with implantation by postcoital estrogen administration. II. Endometrium epithelial cell ultrastructure.

Secretory human endometrium was studied by electron microscopy after high-dose ethinylestradiol administration, a method used for interception (morning-after pill). Medicated (experimental) cycles were compared to non-medicated (control) cycles in the same volunteers. The nucleolar channel system typically present in the nucleus of the epithelial cell in secretory phase of the human endometrium disappears completely as a result of this treatment, resulting in a nucleolar basket structure. Glycogen deposits were prominent at the basal membrane and in the apex of the cell during the experimental cycle. Giant mitochondria were observed to occur to similar extent during control and treatment cycles. This study confirms the morphological delay found in light microscopic studies, published earlier with diethylstilbestrol and with ethinylestradiol.

Administration, Oral↗
PubMed1988

Characterization of human soft tissue sarcomas in nude mice. Evidence for histogenic properties of malignant fibrous histiocytomas.

Twenty-two human sarcomas were grafted subcutaneously into nude mice. Twelve tumors grew successfully. Nine of these 12 tumors had an aneuploid DNA content, whereas only 1 of 10 nonsuccessful tumors was aneuploid. The 12 sarcomas included two leiomyosarcomas, two malignant schwannomas, one synovial sarcoma, and seven malignant fibrous histiocytomas (MFHs). With light and electron microscopic and immunolabeling studies the original and xenografted tumors (the latter for at least two generations) were histopathologically compared. The xenografted leiomyosarcomas showed ultrastructurally a more pronounced leiomyodifferentiation, and one of the malignant schwannomas a more pronounced schwannian differentiation. The second malignant schwannoma and the synovial sarcoma, however, remained unchanged. Five storiform pleomorphic MFHs expressed features that were not observed in the original tumors. Tumor cells of three of these xenografted sarcomas showed leiomyogenic differentiation (filamentous densities, pinocytotic vescicles, and desmin immunoreactivity), whereas cells of the two others demonstrated schwannian differentiation (long cytoplasmic processes, basal lamina). A xenografted myxoid MFH and a pleomorphic MFH gave rise to pleomorphic sarcomas composed of undifferentiated cells. It appeared that under transplantation conditions tumor cells of storiform pleomorphic MFH can differentiate into various directions.

Animals↗
PubMed1987

Cellular composition of follicles of follicle centre cell lymphomas in relation to germinal centres of reactive lymph nodes. A morphometrical electromicroscopical study.

The cell spectrum of neoplastic and benign reactive germinal centres was determined ultrastructurally. The degree in which the cell composition found in reactive germinal centres is maintained in analogous structures of follicular lymphomas was investigated by pattern recognition methods and discriminant analysis based on the frequencies of the various lymphoid and non-lymphoid cell types. The follicular lymphomas included lymphomas with predominantly centrocytes (FCCL, Cb-cc) and lymphomas with predominantly centroblasts (FCCL, Cb). Pattern analysis of FCCL Cb, FCCL Cb-cc and reactive germinal centres indicates that FCCL Cb follicles resemble reactive germinal centres in more aspects than follicles of FCCL Cb-cc. Clear statistical differences were encountered between the frequencies of the lymphoid cell types and of the follicular dendritic and histiocytic reticulum cells in follicles of FCCL Cb-cc and FCCL Cb and reactive germinal centres. Application of a discriminant analysis using a combination of the frequency of centrocytes and follicular dendritic cells demonstrated that both types of neoplastic follicles and reactive germinal centres were correctly classified on the basis of their cell spectrum. For the three groups the most potent discriminator was the centrocyte, whereas the small and large centroblast were of less value. For discrimination between Cb-cc follicles and reactive germinal centres again the centrocyte was the most potent discriminator. Discrimination between FCCL Cb follicles and reactive germinal centres of FCCL Cb-cc follicles can be easily achieved using the frequencies of small centroblasts or centrocytes on their own. These findings indicate that (1) follicles of both FCCL Cb and FCCl Cb-cc differ greatly in the cellular composition and not only with respect to their content of centroblasts but also in their content of follicular dendritic cells and (2) they may be considered as neoplasms representing different developmental phases of germinal centres.

Castleman Disease↗
PubMed1986

Tumor growth stimulatory macrophages induced by a subclinical bacterial infection in vivo.

Nonelicited peritoneal macrophages obtained from normal mice from our animal house unexpectedly expressed a strong tumor growth stimulatory effect in vitro. Macrophages expressing this stimulatory effect had an aberrant morphology compared to the morphology of normal macrophages as observed by electron microscopy. The results of immunization of these affected mice with tumour cells led to the usual lymphocyte sensitization. No external symptoms were observed, and the mice looked healthy. Treatment of the affected macrophage donors with antibiotics resulted in the abolishment of the tumor growth stimulatory effect by the macrophages. Thus, this tumor cell growth stimulation by macrophages was probably due to a subclinical infection of the mice.

Animals↗
PubMed1986

Testing ciliary activity in patients with chronic and recurrent infections of the upper airways: experiences in 68 cases.

The clinical use of various tests of ciliary activity is uncertain and the purpose of this study is to assess the practical significance of the most current methods. Therefore, biopsy specimens of the nasal mucosa were investigated by means of phase contrast microscopy in 68 patients with chronic and recurrent infections of the upper airways. In 19 cases an absent or extremely weak ciliary activity could be demonstrated. Ultrastructurally, a characteristic pattern of defective dynein arms as observed in primary ciliary dyskinesia, was evident in only 3 out of these 19 patients. Measurements of the mucociliary transport velocity by means of intranasal Tc 99m labeled particles appeared to be unreliable in cases of severe nasal obstruction. In this study, phase contrast microscopy of biopsy material from the nasal respiratory epithelium appeared to have the most advantages: It is a practical and rather simple screening test in the assessment of ciliary activity.

Adolescent↗
PubMed1985

An ultrastructural study of cytodifferentiation in the developing human root-tip.

Transmission electron microscopy showed that in growing human teeth, the root sheath consisted of inner and outer epithelial cells. The inner epithelial cells formed a basal lamina associated filamentous layer which increased in density in coronal direction. Extensions of developing odontoblasts were in contact with the basal lamina. Direct contact with the epithelial plasmalemma was not observed. The odontoblasts obtained their fully-developed cylindrical appearance after making contact with the basal lamina of the inner epithelial cells. But, they possessed already abundant RER before these contacts were present, indicating that the differentiation of dental papillary cells into collagen-producing cells did not require heterotypic epithelio-mesenchymal contacts. After deposition of dentine, the odontoblast processes were withdrawn from the epithelium and the outer layer of root dentine. Differentiation of cementoblasts was observed in the dental follicle in which mesenchymal cells develop into RER-containing cells, migrating through apical root-sheath fenestrations to their final position between the continuous root sheath and outer dentinal layer. The findings suggest that all differentiation steps of odontogenic epithelium and odontogenic papillary and follicular mesenchyme proceed without actual contact between epithelium and mesenchyme.

Bicuspid↗
PubMed1984

Primary B-cell malignant lymphoma of the maxilla with a sarcomatous pattern and multilobated nuclei.

Three cases of primary malignant lymphoma of the maxilla are reported. The primary intraosseous origin of these tumors was demonstrated by x-ray examination and surgical exploration. The initial interpretation as odontogenic infection led to a delay in starting therapy of 9 months in one case. Biopsies of two cases were initially interpreted as sarcoma because of a dense reactive fibrosis between the tumor cells. Subsequently, hemimaxillectomy was performed in one case. Histologically and ultrastructurally the tumor cells showed marked nuclear abnormalities with cleavage, folding, and lobulation. Immunohistochemical studies of two cases showed a monoclonal immunoglobulin expression, IgG-K; T-lymphocyte-associated antigens were not detected on the tumor cells. The findings indicate the existence of a primary B-cell malignant lymphoma of bone with multilobated nuclei. The lymphoid nature may be masked by a dense proliferation of connective tissue. The relation of these tumors to the classifications for malignant lymphoma of lymph node is discussed.

Adult↗
PubMed1984

Heterogeneity of epithelial cells in the human thymus. An ultrastructural study.

To evaluate interrelationships among epithelial cells, and between morphology and function in the microenvironment, we studied the ultrastructural morphology of epithelial cells in sections of human thymus from donors aged 2 months to 31 years. Six types of epithelial cells were observed: "subcapsular-perivascular" (type 1); "pale" (type 2); "intermediate" (type 3); "dark" (type 4); "undifferentiated" (type 5); and "large-medullary" (type 6). Cells of types 2, 3 and 4 were found throughout the organ. The type-2 to -4 epithelial cells may represent various stages in a differentiation process. In this, type-2 cells are very active and type-4 cells are possibly degenerating elements. Type-4 cells can also contribute to Hassall's corpuscles. Type-5 cells were located mainly in the cortico-medullary region and showed the morphological characteristics of undifferentiated elements. Type-6 cells were located exclusively in the medulla and displayed characteristics of cellular activity. Small Hassall's corpuscles consisted of type-6 epithelial cells; in larger corpuscles many nuclei of type-6 cells were found. Cells of types 2 and 6 contained tubular structures (diameter approximately 20 nm). Concerning the function of thymus epithelial cells, the features associated with protein synthesis observed in cellular types 2 and 6 make them likely candidates for humoral factor-producing and/or secreting elements. In addition, type-2 and -3 cells in the cortex appear to contribute to a special pattern of epithelium-lymphocyte interaction ("thymic nurse cells"), as demonstrated by the intracytoplasmic location of lymphocytes in the epithelial cells. The various steps in intrathymic T-cell maturation occur at locations in a microenvironment composed of morphologically distinct epithelial cells.

Adolescent↗
PubMed1984

Malignant lymphoma of follicle centre cells with marked nuclear lobation.

Four cases of malignant B-cell lymphoma characterized by a conspicuous component of tumour cells with markedly lobatated nuclei are described. Two exhibited a follicular and two a diffuse growth pattern. The tumour cell population formed a continuous spectrum comprising both cells resembling normal follicle centre cells and multilobated lymphoma cells. Cytomorphological analysis of the multilobated cell group indicated a differentiation series from centroblast-like cells with moderately lobated nuclei to large and medium-sized cells with marked nuclear lobation which revealed features of centrocytes. In three cases (1, 3, and 4) the majority of these multilobated cells showed plasmacytoid differentiation in their cytoplasm in conjunction with the synthesis of monotypical cytoplasmic immunoglobulin. No plasmacytoid features were present in a fourth case (2). In only one case (4) monotypical surface immunoglobulin was detectable on the tumour cells. A close relationship between the multilobated tumour cells and follicle centre cells was further substantiated by the finding of a similar cell variant in the follicle centres of a control group of non-neoplastic lymph nodes. It included cells with plasmacytoid differentiation which synthesized polytypical immunoglobulin. We consider this type of B-cell lymphoma with a conspicuous component of cells with lobated nuclei as a variant of malignant lymphoma, centroblastic/centrocytic.

Aged↗
PubMed1984

Distribution of dendritic reticulum cells in follicular lymphoma and reactive hyperplasia. Light microscopic identification and general morphology.

Reactive and neoplastic follicles in lymph nodes showing changes of (1) follicular hyperplasia and (2) follicular lymphoma were examined for the presence of dendritic reticulum cells (DRC). These cells could be identified under the light microscope after comparing electron microscopical sections with subsequent 1 micro sections of reactive germinal centres. Quantitative light microscopical evaluation showed that DRC, both mononuclear and binuclear forms, were less numerous in neoplastic follicular structures than in reactive follicles. Before determining the frequency of binucleated DRC in follicular tissue their morphology was studied first in cell suspensions. DRC isolated by enzymatic treatment of tonsils and reactive lymph nodes were morphologically identical and contained one, or at most two, nuclei arranged in a typical doublet formation. Stereological calculations - made on three dimensional models of nuclear complexes prepared from serial tissue sections - indicated that 51 to 68% of DRC in reactive germinal centres were binucleated, whereas in neoplastic follicles this figure is 18 to 23%. The multinucleated giant cell forms of DRC described by others result from complex formation with other DRC or lymphoid cells. The smaller number of DRC and the lower frequency of binucleated DRC in follicular lymphomas suggest that differentiation of DRC from stromal cells is less complete in these neoplasms. The ability to identify DRC reliably by light microscopy offers a new means to define the difference in frequency of DRC. This may be of practical value in distinguishing reactive germinal centres from neoplastic follicles.

Cell Count↗
PubMed1983

Histiocytic and dendritic reticulum cells in follicular structures of follicular lymphoma and reactive hyperplasia. A quantitative electron microscopical analysis.

Histiocytic reticulum cells (HRC) and dendritic reticulum cells (DRC) are integral parts of germinal centres. These cell types are also present in follicles of follicular lymphomas, the neoplastic analogues of physiological germinal centres. In this study the distribution and ultrastructural appearances of HRC and DRC present in normal germinal centres and in neoplastic follicles were established by means of morphometric methods. The number of HRC was significantly lower in malignant follicles than in their reactive counterparts. Quantitative analysis of the cytoplasm and phagolysosomes suggest that HRC are smaller and that their activity is lower in malignant follicles. DRC were present in smaller numbers in these structures, as measured by nuclear counts and their relative volume within the follicles. The ultrastructural features indicate that DRC in follicular lymphoma are functionally less active than in reactive lymph nodes. The possibility that differences between the reticulum cells from reactive and neoplastic follicles may be related to the absence of an immune reaction in malignant follicular lymphoma is discussed. The frequency and appearance of HRC and DRC are suitable as additional parameters to differentiate reactive secondary germinal centres from their malignant analogues.

Cytoplasm↗
PubMed1983

Identification and in situ localization of the "thymic nurse cell" in man.

The observation of the "thymic nurse cell" (TNC), a reticuloepithelial cell with intracytoplasmic lymphocytes, in suspension of murine thymic tissue prompted us to investigate the existence of this cell in cell suspension, as well as in tissue sections of the human thymus. TNC-like cells were enriched in suspension by enzymatic disintegration of thymic tissue and 1 X G sedimentation over 50% fetal calf serum gradients. TNC-like cells were negative for lysosomal enzymes: in this respect, as well as in light microscopic morphology, the cells were different from tissue macrophages with intracytoplasmic lymphocytes. In electron microscopy, TNC-like cells showed reticuloepithelial characteristics. In 1-micron tissue sections, clusters of lymphocytes with a possible reticuloepithelial nucleus were observed close to blood capillaries in the cortical area. Ultrastructural analysis confirmed the epithelial nature of this cell, as well as its location adjacent to blood capillaries. We concluded that there is in situ existence of TNC in man. This observation enables studies on the role of TNC in intrathymic T cell maturation.

Cell Differentiation↗
PubMed1979

Pancreatic endocrine cells of Barbus conchonius (Teleostei, Cyprinidae), and their relation to the enteroendocrine cells.

The pancreatic endocrine cells of Barbus conchonius are concentrated in a large (principal) islet, located near the gall bladder, and in a number of smaller islets. Five types of endocrine cells can be distinguished in there pancreatic islets: B cells, A1 (or D cells), 2 types of A2 cells (A2r cells with round granules; and A2fl cells with flocculent granules) and a scarce 5th cell type. The hormones produced by B and A2fl cells are probably insulin and glucagon respectively. The A2r cell contains granules with the same diameter as the granules of the enteroendocrine type III cell of the gut. Both cell types may resemble the enteroglucagon-producing EG cell of mammals. The function of the A1 cells, which are frequently found without secretory granules, and of the 5th cell type, will be discussed. The pancreastic islets of B. conchonius are strongly innervated, which suggests thatpresence of a direct nervous control system. Some intermediate or mixed cells containing exocrine and endocrine A2r granules are found continguous with the principal islet. The origin of pancreatic endocrine cells is also the subject of discussion.

Animals↗