Quantitative assessment of various fixatives on nuclear and cytoplasmic areas in oral cytology

Both nuclear and cytoplasmic areas are parameters known to be of significance in the diagnosis of malignancy. However, few studies have assessed the effect of fixation on exfoliative cytology and none has looked at such influences upon oral smears. Hence the method of fixation may influence directly diagnostic cytology. The effect of three methods of fixation upon the nuclear and cytoplasmic areas of cells removed from the buccal mucosa was quantitatively assessed. The three methods employed, prior to Papanicolaou staining, were: direct immersion in diethylether and ethanol (1:1 v/v), spray fixation (Vale Smear Fix) and air drying. Three smears from each of 21 patients were used, each slide being allocated randomly a method of fixation. After 24 h all smears were processed for Papanicolaou's stain. The nuclear and cytoplasmic areas were calculated using semi-automated image analysis. No significant differences were found in the two areas whichever method of fixation was used.

Electron microscopic detection of human papillomavirus particles in oral proliferative lesions

Human papilloma virus (HPV) has been demonstrated in a series of benign proliferative lesions of skin and mucosae. To prove the distribution of HPV in the oral proliferative lesions at the ultrastructural level, we performed electron microscopic analysis of 10 specimens taken from 5 patients through large excisional biopsy. All of them were diagnosed pathologically as fibropapilloma. In each patient, specimens were taken from both clinically evident proliferative lesions and clinically normal surrounding mucosa. Obtained specimens were fixed in a glutaraldehyde solution and processed for routine ultrathin sectioning. Before electron microscopic observation, the tissue sections on copper grids were subjected to amylase digestion of glycogen granules. Spherical viral particles of 40-55 nm in diameter were detected the non-keratinized epithelial cells in all specimens examined. Of particular interest were the large amounts of viral particles found in the cytoplasmic matrix and nuclei (especially on their chromatin masses) of the cells in intermediate and surface layers, which did not form a crystal array. All the membranous cell organelles of epithelial cells were, however, devoid of viral particles. Some viral particles were distributed in the extracellular spaces of an intermediate layer. Viral particles were hardly observed in the cells of a basal/suprabasal and prickle cell layers. There were no significant differences in the HPV distribution between the cells derived from the proliferative lesion and those derived from the surrounding normal mucosa.

Heterogeneity of chromosomal breakage levels in epithelial tissue of ataxia-telangiectasia homozygotes and heterozygotes

The objective of this study was to obtain an estimate of the frequency distribution of spontaneous chromosomal breakage occurring in vivo in oral epithelia of 20 ataxia-telangiectasia patients (A-T homozygotes) and 26 parents (A-T obligate heterozygotes). Samples of exfoliated cells were obtained from each individual by swabbing the oral cavity and preparing air-dried slides. The percentage of exfoliated cells with micronuclei (MEC frequency) was used as an in vivo indicator for the amount of chromosomal breakage occurring in the tissue. As a population group, MEC frequencies of the A-T patients differed significantly from controls (mean for A-T patients, 1.51; for controls, 0.29; P less than 0.01). However, the values observed in individual patients ranged from MEC frequencies 10- to 12-fold above control values, to frequencies overlapping the upper values observed in the controls. Similarly, MEC frequencies observed among the A-T heterozygotes differed significantly from controls (mean for A-T heterozygotes, 1.02, mean for controls, 0.29; P less than 0.01). However, only 16 of the 26 individuals sampled had MEC frequencies greater than 0.5%, the 90th percentile for controls (compared with 16 of the 20 A-T patients examined). Of the A-T patients 11 had been previously assigned to complementation groups on the basis of sensitivity to x-irradiation. Seven of the patients belonged to group A and had MEC frequencies ranging from 0.3% to 1.9% with the remaining patients belonging to group C with MEC frequencies of 0.2% to 0.9%. The data presented in this paper suggest that although levels of spontaneous breakage in epithelial tissues of A-T patients and A-T obligate heterozygotes are often significantly elevated, this is not the case in all individuals.

Ultrastructural findings in oral hyperpigmentation of HIV-infected patients

Oral hyperpigmentation has been observed in six HIV-infected patients, in two of whom systemic medication (ketokonazole, clofazimine) was supposed to be etiologically involved. Histologically, pigment was found in epithelial basal cells and particularly in subepithelial connective tissue. Ultrastructurally, the presence of premature melanosomes in subepithelial keratinocytes was of interest. Stimulation of melanocytes during HIV infection may occur in association with immunopathologic changes in the oral mucosa.

Effect of radiotherapy on oral mucosa assessed by quantitative exfoliative cytology

The effect of radiotherapy on normal buccal mucosa was investigated using the quantitative techniques of cytomorphology (measurement of nuclear and cytoplasmic area) and DNA cytophotometry. These techniques were applied to smears obtained before, during, and after irradiation. Nuclear area and cytoplasmic area increased and DNA values were abnormal in most cases as a result of radiotherapy, returning to within normal limits one month after treatment. This contrasts strongly with the changes seen in smears from previously irradiated uterine cervices, where changes in cytomorphology may persist for several years.

[Observation with SEM on the displacement of mucosal surface in process of denture fabrication]

The process of denture fabrication entails a series of steps that begin with impression-taking. Dimensional accuracy and displacement of surface repeatability affect results in these individual steps. Although changes in individual materials have already been measured in the past, there has been almost no measurement up to now of denture fabrication up to the denture base, using the mucous membrane as the standard and then measuring changes in the displacement of surface repeatability for each step. Noticing this lack, the authors used a Scanning Electron Microscope (SEM), presently the only non-contact measuring instrument that can be used, and measured changes at the different stages including the mucous membrane, the impression materials, the plaster and the resin. A drying process is required for the mucous membrane, and such a process can cause changes in the mucous membrane which is the basis of measurement. For this reason, the authors used Araldite, a product from Ciba-Geigy AG, as a replica material and made replicas for all the test materials, using the replicas for measurement. Results were as follows: 1. Araldite was used as the replica material, thus making it possible with the SEM to observe changes in the displacement of surface repeatability at the individual stages. 2. Major changes in the accuracy of surface were observed during impression-taking and in the period of moving from the impression material to the plaster. 3. During high-power observation with the SEM, the fine bumps on the surface of the plaster and resin disappeared and the surfaces became smooth. This is believed to be the result of the separating agent and heat.

Ancient neurilemmoma (Schwannoma) of the oral cavity

Ancient neurilemmoma is a rare lesion of the oral cavity. The present article describes an additional case and discusses some difficulties in its histological diagnosis. The final diagnosis is based on both light and electron microscopy morphology. Immunohistochemical studies are, at present, only of supportive value.

Ultrastructure of cultured canine oral keratinocytes

Keratinocytes from explants of the oral mucosa of dogs were grown in culture for five passages. The ultrastructure of primary cultures and fully developed subcultures passaged 1, 3, and 5 times was examined. At every stage, the cells had the morphologic characteristics of epithelial cells and formed a multilayered squamous epithelium. The basal cells had the characteristics of metabolically active cells, whereas the suprabasal cells and the cells at the media interface expressed many, but not all, of the organelles and cell surface characteristics associated with keratinocyte differentiation. Keratohyalin granules were located in the suprabasal and superficial cells. Cell size and shape and the relationship between cells in the layers also reflected the morphologic characteristics of the parent tissue. Cells maintained this typical structure through all passages and the cultures changed minimally for up to a week after development.

[Ultrastructure of colloid bodies in oral lichen planus]

Ultrastructure of 20 cases oral lichen planus was observed. Colloid bodies were found in 4 cases. Morphologically, the colloid bodies could be divided into four types: Mass-filament shape: compound type of mass-filament shape and filament shape of low electronic density; filament shape of low electronic density and filament shape of high electronic density. Among them, the compound type was not reported until this study. Owing to discovery of the compound colloid body, the fact that there is an intermediate stage in the course of formation of the colloid body was more correctly known by the authors. And a model figure which expressed the course of formation of colloid bodies was drawn up. The authors have imagined the nature of colloid body is degeneration of epithelial cells. The result of degeneration is death of the cells.

Primary fixation of vervet monkey oral epithelium for ultrastructural investigation--SEM

Vervet monkey attached gingiva and alveolar mucosa was used to investigate the effect of primary fixative composition and osmolarity on the scanning electron microscope appearance and epithelial cell surface feature density. Primary fixation was obtained using 12 different fixatives with osmolarities varying between 320-2010mOsm followed by further standard SEM processing procedures. All primary fixatives investigated produced acceptably fixed oral epithelium for SEM study, showing all the morphologic features characteristic of either keratinized or non-keratinized oral tissue. Point counting revealed that the density of microvilli of attached gingiva epithelial cells when fixed at 2010mOsm was 72 +/- 8% of the cell surface area. This decreased to 40 +/- 5% when fixed at 320mOsm. Similarly the microplication density of the alveolar mucosa epithelial cells decreased from 70 +/- 5% at 2010mOsm to 43 +/- 7% at 320mOsm. Both these differences proved to be highly significant.

A clinical, radiographic, and histological evaluation of permucosal dental implants of dense hydroxylapatite in dogs

A clinical, histological, and radiographic examination was performed on 77 permucosal dental implants, made of dense sintered hydroxylapatite: 34 solid cylinders and 43 hollow cylinders. The hollow cylinders were pre-compressed between two titanium caps. The implants were placed in partly edentulous mandibles of dogs, and were physiologically loaded. Healing was clinically and radiographically evaluated during a six-month to five-year period. At various times, implants with their surrounding tissues were removed and prepared for light and electron microscopy. All implants showed a good initial fit and were maintained in place without undercut or mechanical stabilization. After 18 months, 76% of the solid cylinders had fractured at the implant/bone junction due to fatigue. However, the submerged portions of the solid cylinders were preserved without clinical problems, and became entirely embedded in bone. The pre-stressed implants did not fracture, and 91% were functioning 24 months after placement. The average scores of pocket depths and gingival bleeding showed no significant differences between implants and surrounding natural teeth. Bone deposition occurred on the entire surface of the implant below the crest of the alveolar bone, and intimate bone contact was confirmed by electron microscopy. It was also observed that a layer of bone tissue was deposited on the implant surface in the permucosal area just above the alveolar bone level. Embedding of gingival fibers in this layer resulted in gingival attachment to the implant, comparable with that of natural teeth.

[Connecting pattern of rabbit surface buccal epithelial cells: a scanning electron microscopic study]

Rabbit buccal epithelial cells were studied by scanning electron microscopy. The cell surface was covered with type 4 microridges. The surface was also segmented by cellular borders and attached borders. Small area enclosed by the attached border was often elevated from the surrounding areas. The intervals of the microridges of this small protrusion were narrower than those of the surrounding area and resembled those of type 5 microridges. These findings suggest that exposure of the cell membrane to the external environment induces morphological changes in the microridges. The area surrounded by cellular borders, which was considered to have become small protrusions, was also observed. These observations suggest a staggered lamination of cell stacks and the penetration of a part of cell surface of the lower layer into the cellular space of the upper layer, forming an interdigitation. This cell arrangement is considered to enhance the strength of the binding of the cells.

The frog palate mucosa as a model for studying bacterial adhesion to mucus-coated respiratory epithelium

Most of the methods proposed to quantify bacterial adherence to respiratory mucosa differ mainly from in vivo conditions in the absence of the mucus blanket and in the exposure of the sub-mucosal connective tissue (SMCT) to the micro-organisms. We propose the frog palate as a model to study bacterial adhesion to the respiratory mucosa, with a system which allows the mucus to be preserved and the bacterial adhesion to be quantified in a standardized mucosal area, where mucociliary transport is still active. In order to evaluate the role of respiratory mucus in bacteria-mucosa interaction, we compared the adhesion of radiolabelled pneumococci to 12 mucus-coated and 10 non-mucus-coated frog palate mucosae. The presence or absence of mucus was controlled by scanning electron microscopy (SEM). After a 10 min incubation period, the bacterial adhesion to mucus-coated palate mucosa was five times greater (P less than 0.01) than that to uncoated mucosa. By SEM, bacteria were never seen attached to ciliated cells but could be detected on small areas where mucus was not totally eliminated. Even after a 120 min contact of bacteria to uncoated mucosa, bacterial adhesion remained only half that to mucus-coated epithelium. In order to ascertain whether the exposure of the SMCT represented a means of attraction to bacteria, we incubated the frog palate mucosa face-down with radiolabelled Pseudomonas aeruginosa. As much as 44 per cent of added bacteria adhered to exposed SMCT and, by SEM, numerous micro-organisms were seen attached to connective tissue. In contrast, only a few bacteria were observed adhering to the mucosa, mainly to granules of mucus.

Ultrastructural findings in clinically uninvolved oral mucosa of patients with HIV infection

Twelve biopsies of clinically normal oral mucosa taken from HIV seropositive patients have been investigated by means of light- and electron microscopy. Vascular abnormalities were found in all biopsies, regardless of the clinical stage of the HIV infection. In particular slit-like vascular channels, sparseness of intercellular junctions and swollen, protruded endothelial cells with an increased quantity of Weibel-Palade bodies were noticed. These findings were similar to those described in lesions of early stage Kaposi's sarcoma.

[Hyperplasia of gingivae in the course of incomplete form of Melkersson-Rosenthal syndrome]

A case of incomplete Melkersson-Rosenthal (s. M-R) syndrome manifesting itself by the lower lip and cheeks' mucous membrane oedema and hyperplasia of gingivae has been described. Histopathological examination of the cheeks has demonstrated disseminated, perivascular inflammatory infiltrations of sarcoid type, whereas massive infiltration composed nearly exclusively of plasmatic cell has dominated in segments of gingivae. Electron microscopic examination has demonstrated increased migration of the cells resembling lymphocytes through the epithelium towards the surface and progressive morphological changes leading to the disintegration both lymphocytar cells and plasmatic ones and symptoms of interstitium fibrotic processes.

Experimentally induced bluetongue virus infection in white-tailed deer: ultrastructural findings

White-tailed deer (Odocoileus virginianus) were inoculated with bluetongue virus serotype 17 and sequentially euthanatized during infection. Ultrastructural changes in the microvasculature of tongue, buccal mucosa, heart, and pulmonary artery, platelets, and bone marrow were evaluated. Bluetongue virus was found in endothelial cells of the microvasculature by postinoculation day 4. Viral replication was associated with the development of viral matrices, viral-associated macrotubules, and aggregates of mature viral particles in the cytoplasm of infected cells. Viral infection of pericytes and vascular smooth muscle cells developed subsequent to endothelial cell infection. Viral infection was associated with striking changes in the endothelial lining of the microvasculature by postinoculation day 4. Endothelial cell degeneration and necrosis, which resulted in denudation of the endothelial lining, and endothelial cell hypertrophy frequently were observed. Thrombosis, hemorrhage, and vessel rupture developed subsequent to endothelial damage. Bluetongue virus neither infected nor directly damaged platelets or bone marrow cells. It was concluded that viral-induced endothelial damage is the primary triggering mechanism for disseminated intravascular coagulation in bluetongue virus infection. Vascular damage coupled with the development of disseminated intravascular coagulation is responsible for the hemorrhagic diathesis, which is characteristic of bluetongue virus infection in white-tailed deer.

DDAVP and epinephrine-induced changes in the localization of von Willebrand factor antigen in endothelial cells of human oral mucosa

A peroxidase-labeled antibody technique revealed von Willebrand factor antigen (vWF:Ag) in rough endoplasmic reticulum (rER), the perinuclear region, and the cytoplasmic vesicles of capillary endothelial cells in oral mucosa. After administration of epinephrine or 1-deamino-8-D-arginine vasopressin (DDAVP), the localization of vWF:Ag was shown to have changed to the basement membrane and the surrounding interstitium. This change of vWF:Ag localization induced by epinephrine and DDAVP may play a role in the adhesion of platelets to subendothelium following endothelial injury during surgery and may be an unknown hemostatic effect of these drugs.

Ameloblastoma of mucosal origin

Histopathological, histochemical and ultrastructural findings of an extraosseous ameloblastoma occurring in an 89-year-old woman are reported. Rete pegs of the gingival epithelium covering the lesion showed marked extension into the lesion, and direct continuity between the extended rete pegs and tumor follicles was evident. Ultrastructural examination showed that the rete pegs gradually became transformed into double-stranded epithelial cords as they elongated deeply, and that the ends of these epithelial cords gradually became transformed into tumor follicles. These findings suggest that the potential for differentiation is maintained in the basal cells of the gingival epithelium throughout life, and can be triggered by unknown stimuli. The ultrastructure of the tumor follicles was similar to that of intraosseous follicular ameloblastoma, but was different from that of cutaneous basal cell carcinoma. Histochemical staining for keratin protein revealed that the central cells of tumor follicles and the covering epithelium were positive, whereas the peripheral cells of tumor follicles and the elongated rete pegs were negative.