Ultrastructure et constitution des corps nucl�aires dans les plasmocytes

Nucleic acid compartmentalization within the cell nucleus by in situ transferase-immunogold techniques

In the present review, we report on recent results obtained by in situ transferase-immunogold techniques as to the ultrastructural distribution of DNA and RNA within the cell nucleus. Special emphasis is placed on the various nucleolar components and the various enigmatic structures of the extranucleolar region: interchromatin granules, coiled bodies, and simple nuclear bodies. These data are discussed in the light of our current understanding of the functional organization of the cell nucleus.

Human cytomegalovirus nuclear and cytoplasmic dense bodies

One of the characteristic features of cytomegalovirus (CMV) replication is the formation of cytoplasmic dense bodies. Recent findings revealed similar structures also in the nuclei of CMV-infected cells. By transmission electron microscopy, immuno electronmicroscopy, and cytochemistry, we have studied the morphogenetic steps and macromolecular composition of both structures. Our results show that both structures contain DNA, RNA and viral antigenic proteins. Nuclear dense bodies are probably an expression of a stimulated cellular metabolism, while cytoplasmic dense bodies may represent the site where surplus cellular and viral molecules are stored before being eliminated.

Intranuclear rodlets and associated true intranuclear bodies in normal cultured human dermal papilla cells

The dermal papilla is believed to exert controlling influences on hair growth. This report documents, for the first time, the occurrence of intranuclear rodlets in normal cultured human dermal papilla cells. Intranuclear rodlets have been observed predominantly in normal neurons, neural neoplasms, and paraneuromas. Whereas intranuclear rodlets and complex intranuclear bodies have not been identified in dermal papilla cells in vivo, they were observed, by light microscopy and transmission electron microscopy, in primary and subsequent passaged cultures in all 10 individuals examined. Intranuclear rodlets and bodies were not found, however, in parallel cultures of scalp dermal fibroblasts from the same individuals. Rodlet ultrastructure in cultured dermal papilla cells exhibited many features in common with previous reports on rodlets in neuronal and paraneuronal cells. Features that differentiated the rodlets in this study, however, included: doublet/triplet rodlets in the same nucleus; rodlets or crystalline filament bundles within complex nuclear inclusions; close relationship with the nuclear membrane, and their frequent intimate association with intranuclear bodies; and nucleoli and fine chromatin-distinct fibrillar material. Although the function of these true intranuclear inclusions in dermal papilla cells is unknown, it is noteworthy that they were present in these highly metabolically active fibroblasts while absent in comparatively less active dermal fibroblasts, and may indeed be a marker for this fibroblast cell type.

Nucleolus-associated J chains in myeloma cells

Bone marrow aspirates from 10 patients with multiple myeloma (6 IgG myeloma, 3 IgA myeloma, 1 Bence Jones myeloma) were examined for nucleolus-associated localization of J chains. On light microscopy using the PAP method, almost all or a significant number of myeloma cells exhibited intranuclear spots stained with anti-J chains in 3 (IgG myeloma) out of the 8 cases positive for cytoplasmic J chains. In contrast, the nucleus of myeloma cells examined was constantly negative for anti-heavy and -light chains. Immunoelectron microscopically, J chain was identified as dicrete round electron-dense precipitates, corresponding to the whole nucleolus, and as sparsely distributed, small electron-dense deposits in the nucleus. In addition, some connections were found between nuclear and nucleolar electron-dense precipitates. Several possible explanations have been proposed to account for this localization of J chains.

Follicular dendritic cells in lymph nodes after x-irradiation

Follicular dendritic cells (FDC), non lymphoid cells present in lymph follicles, are characterized by numerous cytoplasmic processes retaining antigen-antibody complexes. Their origin, nature and function are unknown. Mice inguinal lymph nodes after 4.5 or 7.5 Gy X-irradiation were depleted of lymphoid cells. Ultrastructural observations during the first few days post-irradiation show that FDC are unaltered and possess dendritic processes enveloping dense material. Furthermore, they show intense metabolic activity. A lamina densa, never observed so well-developed in other lymph node cells, was detected around the nuclear envelope. The localization of junctions between FDC was analysed. FDC preserve their typical cytoplasmic processes even if lymphoid cells are rare. The latter thus seem not to be responsible for the maintenance of FDC integrity or their development. The possible role of this for antibody production is discussed. Irradiated lymph nodes of lymphoid cells are highly convenient for studying FDC. Isolation of FDC from irradiated lymph organs would seem to be possible.

The ultrastructure of bone marrow plasma cells obtained from patients with multiple myeloma during the clinical course of the disease

The ultrastructure of plasma cells from 65 consecutive bone marrow specimens from 13 patients with multiple myeloma is described. Biopsies were taken from 12 of the patients prior to and after initiation of treatment. The study was undertaken with the aim of correlating ultrastructural characteristics of the myeloma cells with biochemical and clinical parameters, including the survival time after treatment of the patients with cytostatics. Intranuclear inclusions were only seen in the cells of four patients, all of whom had rather long survival times. Two of these are still alive and, furthermore, their plasma cells are characterized by a low mean number of mitochondria in each sectioned cell studied, i.e. 7 and 14, respectively. Nuclear bodies were found in about 7 per cent of the plasma cells in biopsies taken before treatment was initiated. During treatment this percentage increased significantly to about 16 (2P = 0.004). A nuclear/cytoplasmic asynchrony was a characteristic feature of the ultrastructure of the myeloma cells. During treatment a significant increase from 34 to 54 per cent (2P = 0.03) was observed in the number of plasma cells with slight asynchrony. No correlation could be established between any ultrastructural features and the values obtained with clinical tests considered of major prognostic significance at the time of diagnosis, e.g. the concentrations of serum creatinine, haemoglobin, serum albumin and serum calcium.

The origin of nuclear bodies: a study of the undifferentiated epithelial cells of the equine small intestine

During an electron and light microscopic study of the equine intestinal epithelium, it was observed that some secretory granules of the undifferentiated crypt epithelium were incorporated into the nucleus during mitosis. A study was made of the chemical nature of the granules, using standard histochemical techniques: PAS-Alcian blue, Deamination-PAS, and Ninhydrin-Schiff reactions. The granules contained a neutral protein-polysaccharide complex with many terminal amino groups, possibly an antibody (IgA). The intranuclear granules underwent coalescence and degeneration during differentiation. The end-product was identical with the nuclear bodies seen in other somatic cells and described in the literature. These nuclear bodies were seen in absorptive cells, goblet cells, and Paneth cells; but were not observed in any entero-endocrine cells. This study shows that the nucleus is capable of isolating and degrading unwanted material, foreign and internally generated, and, further, it gives an explanation for the origin of nuclear bodies, structures that have long been an enigma in cell biology.

On the occurrence of sphaeridia in basalioma cells and the basal cells of the overlying epidermis

302 nuclear sections of basalioma cells, 145 nuclear sections of the basal cells of the epidermis above the tumor, and 177 nuclear sections of the basal cells of normal epidermis were investigated and statistically evaluated with the aim of determining the presence of sphaeridia occur significantly more frequently in the basal cells of the epidermis above the tumor and in normal epidermis than in the tumor itself. These findings are discussed in connection with the degree of cellular protein synthesis.