An ultrastructural study of binucleate plasma cells

Fifty surgical specimens from 10 different diseases were examined for the presence of binucleate plasma cells. Thirty-three specimens showed binucleated plasma cells. Morphologically, they resembled mononuclear cells and contained abundant basophilic cytoplasm which ultra-structurally showed extensive rough endoplasmic reticulum. Their 2 nuclei exhibited the "cart-wheel" arrangement of heterochromatin characteristic of plasma cells. When serially examined the 2 nuclei remained separate. In addition, pairs of closely apposed plasma cells were observed. Some of these cells showed distinct opposing membranes separated by a gap of approximately 15nm. While others, exhibited localised areas of indistinct membranes. There were also pairs of closely apposed plasma cells showing cytoplasmic bridges. These results suggest that the mode of formation of binucleate plasma cells is probably cell fusion. They also show that these binucleate cells are not confined to a single disease as they were found in 10 different diseases.     

An ultrastructural study of binucleate plasma cells

Fifty surgical specimens from 10 different diseases were examined for the presence of binucleate plasma cells. Thirty-three specimens showed binucleated plasma cells. Morphologically, they resembled mononuclear cells and contained abundant basophilic cytoplasm which ultra-structurally showed extensive rough endoplasmic reticulum. Their 2 nuclei exhibited the "cart-wheel" arrangement of heterochromatin characteristic of plasma cells. When serially examined the 2 nuclei remained separate. In addition, pairs of closely apposed plasma cells were observed. Some of these cells showed distinct apposing membranes separated by a gap of approximately 15 nm. While others, exhibited localised areas of indistinct membranes. There were also pairs of closely apposed plasma cells showing cytoplasmic bridges. These results suggest that the mode of formation of binucleate plasma cells is probably cell fusion. They also show that these binucleate cells are not confined to a single disease as they were found in 10 different diseases.     

Temperature dependence of toothbrush bristle morphology An ultrastructural study

Abstract. In this study, it was demonstrated that the original forms of toothbrush bristle ends undergo morphological changes during the preparatory procedures required prior to their examination by scanning electron microscopy (SEM). In particular, the distance of the specimens from the cathode of a traditional sputter-coater and the time of gold-palladium coating influence the temperature inside the vacuum compartment. Morover, the temperature influences the original morphology of toothbrush bristles, 2 segments of each toothbrush head with nylon or ultralon bristles were cut off the brush: one was mounted vertically and one horizontally on stubs for SEM analysis. Different temperatures were measured inside the sputter-coater at the level of the bristle ends, during coating with gold-palladium alloy. The temperature at the level of the bristles that were placed horizontally was about 38°C, and 59°C when they were placed vertically. SEM analysis of the specimens showed that the same toothbrush has end-rounded bristles at about 59°C and non-acceptable irregular bristles at about 38°C. Retraction of bristles (which appeared shortened and with increased diameters) and superficial cracks were particularly present in the vertically placed ultralon bristles.     

An ultrastructural study of tooth resorption in the kitten

Eleven kittens of various ages were used to obtain teeth in situ at differing stages of exfoliation. The teeth were processed by routine techniques for examination by light and transmission electron microscopy. The dental hard tissues were eroded by odontoclasts supported by numerous blood vessels, fibroblasts, and macrophages. No evidence of intracellular collagen was found within any of these cells, indicating that helper cells are not required to remove the collagenous component of dentin and cementum. The loss of periodontal ligament during shedding involved the removal of cells and extracellular material. Two forms of fibroblastic cell death were identified: One, apoptotic cell death, involved condensation, and its occurrence suggests that exfoliation of deciduous teeth is a programmed physiological event; the other occurred in cells containing many profiles of collagen and involved the selective disruption of the mitochondria and eventual dissolution of cytosol. This form of cell death has not been previously described and is significantly different from necrotic cell death, which was not observed during exfoliation. Some fibroblasts maintained a normal morphology. These various cellular responses suggest that phenotypically different populations of fibroblasts may exist in the periodontal ligament. Collagen removal was an extracellular occurrence which did not seem to involve increased phagocytotic activity by fibroblasts.     

An ultrastructural study of the fibrillary component of dental tissues

The recent interest for highly sophisticated techniques of dental tissue preparation aiming to display very particular structures, moved the AA. to improve the literature suggestions. In particular they made TEM and SEM observations of transitional zones between healthy and normal pulp and dentin after decalcification and trypsin at different concentrations treatment. The images obtained draw in the attention the study facilities of a technique that really removes all the non collagenic material. The data obtained in the pericellular zones also allowed some interventions in the recent literature discussion about inter-odontoblastic fibres.     

An ultrastructural study of the pocket epithelium in rats.

The purpose of the present study was to elucidate the biological characteristics of pocket epithelium in experimental periodontitis. Elastic rubber was inserted between the first and second molars of the left maxilla in rats. The rubber was removed after one week, and the animals were sacrificed one week after the removal, i.e., two weeks after the insertion. Sections of the teeth and surrounding tissues were examined by electron microscopy. Periodontal pockets were evident between the tooth surface and epithelial cell layer in the coronal portion. A large number of bacteria surrounded by neutrophils were observed on the cementum surface in the pocket; however, no bacterial invasion could be seen in the epithelium. The epithelial cells were spilt in the central portion by invasion of neutrophils, so that one or two layers of surviving epithelial cells were present on the cementum surface. Numerous fenestrations of capillaries were found in the connective tissue immediately below the epithelium. These results suggest that the pocket epithelium is formed by an intercellular split of the epithelium, not between cementum surface and epithelium.     

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.     

Effect of 3 dentifrices containing triclosan and various additives. An experimental gingivitis study

BACKGROUND: The antiplaque and antigingivitis effect of 3 dentifrices was evaluated using the 21-day partial-mouth experimental model of gingivitis. METHOD: 25 volunteers took part in this cross-over, double-blind study, carried out in 4 phases of 21 days each. For each phase of the study, a toothshield of the IV quadrant was constructed for each volunteer. 2 antiplaque dentifrices from the market, one containing triclosan + pvm/ma and the other triclosan + Zn, were compared with an experimental formulation and its placebo. The experimental dentifrice contained triclosan + pvm/ma + Zn + PPi and the placebo (control) did not contain these substances. The subjects were stratified according to their whole-mouth baseline plaque (PI), gingivitis (GI) and bleeding (BI) index scores, and then randomly assigned to 1 of 4 dentifrices. During each phase, while the volunteers brushed their teeth with one of the dentifrices, the IV quadrant was protected by the toothshield filled with the dentifrice used. After each phase, dental plaque, gingivitis and bleeding indices were determined. RESULTS: The results showed that only the formulation containing triclosan + pvm/ma + Zn + PPi was able to reduce PI (28.8%), GI (35.9%) and BI (30.4%) in comparison with controls (p<0.05). CONCLUSIONS: The data suggest that a dentifrice containing the combination of triclosan + pvm/ma + Zn + PPi should be formulated for dental plaque control.     

An ultrastructural and immunohistochemical study on mandibular lesion of Letterer-Siwe disease

A mandibular lesion from an infant with Letterer-Siwe disease was studied by electron microscopy and immunohistochemistry. Ultrastructurally, two types of cells were identified; clear and dark cells. Clear cells had indented nuclei and Langerhans cell granules, while dark cells were characterized by the occasional presence of a large number of lysosomes. Lysozyme was usually not detectable in proliferating cells with indented nuclei, but it was strongly positive in cells without indented nuclei. The latter also usually contained IgG, although the occurrence of cytoplasmic IgM, A, D and E seemed to be negative in both types of cells. Thus clear cells showed a close resemblance to Langerhans cells and dark cells had features of ordinary histiocytes. Although the intimate relationship between these two types of cells remains obscure, our findings suggest that Letterer-Siwe disease may be a reactive or tumorous condition of a cellular subpopulation of Langerhans cells with a proliferation of differentiated histiocytes.     

A longitudinal study of gingivitis and puberty

A longitudinal study of 127 children between the ages of 11 and 17 years revealed a high initial prevalence of gingivitis that tended to decline slightly with age. The distribution of the ages of the children when experiencing their observed maximum amount of gingivitis was consistent with the hypothesis that there is a relationship between puberty and gingivitis. There was also evidence that at the time of the peak gingivitis experience the gingival tissues were exhibiting a heightened response to irritation.