Human Palatal Mucosa Research Articles

Histological and histomorphometric study of human palatal mucosa: Implications for connective tissue graft harvesting.

To analyse the histological structure and histomorphometric characteristics of human hard palatal mucosa in order to determine the donor site of choice for connective tissue grafts from a histological point of view. Palatal mucosa samples from six cadaver heads were harvested at four sites: incisal, premolar, molar and tuberosity. Histological and immunohistochemical techniques were performed, as was histomorphometric analysis. In the current study, we found that the density and size of cells were higher in the superficial papillary layer, whereas the thickness of the collagen bundles increased in the reticular layer. Excluding the epithelium, the mean percentage of lamina propria (LP) and submucosa (SM) was 37% and 63%, respectively (p < .001). LP thickness showed similar values in the incisal, premolar and molar regions, and a significantly greater thickness in tuberosity (p < .001). The thickness of SM increased from incisal to premolar and molar, disappearing in the tuberosity (p < .001). As dense connective tissue of LP is the tissue of choice for connective tissue grafts, the best donor site from a histological point of view is tuberosity because it is composed only of a thick LP without the presence of a loose submucosal layer.

Whole transcriptome analysis of smoker palatal mucosa identifies multiple downregulated innate immunity genes.

Smoking has significant negative impact on periodontal health and treatment outcomes. The molecular effects of smoking on oral immune homeostasis have not been fully elucidated. The present study aimed to provide a comprehensive assessment of smoking-associated gene expression changes in healthy palatal mucosa and to identify potentially implicated immunologic pathways. Palatal biopsies, in the form of connective tissue grafts, were obtained from periodontally healthy smokers and non-smokers. Smoking status was biochemically verified (exhaled air CO and serum cotinine). Tissue samples were processed for next generation sequencing, quantitative real-time polymerase chain reaction (qPCR), and immunohistochemistry. Gene set enrichment/pathway analysis and correlation analysis between gene expression and serum cotinine levels were also performed. Analysis of palatal tissues from 12 non-smokers and 10 smokers identified 830 significantly (P <0.05) differentially expressed genes (DEGs), 249 with fold change (FC) >2. Most increased in expression (≥5-FC) were CYP1A1, CYP1B1, and USP17L9P; most decreased (≥6-FC) were IL36A, DEFB4A, DEFB4B, SPRR2F, CCL20, KLK6, and ADH4. 203 DEGs (FC >2) were significantly correlated with serum cotinine levels. Significant enrichment pathways for cotinine-associated genes include antimicrobial humoral response, regulation of humoral response and various metabolic processes. qPCR and immunohistochemistry confirmed gene and protein expression of selected DEGs. Smoking has a significant effect on the transcriptome of normal human palatal mucosa and seems to target genes important for innate immune defenses, which may prove to be one of the key mechanisms by which tobacco smoking leads to increased periodontitis susceptibility.

Differential Mucosal Gene Expression Patterns in Candida-Associated, Chronic Oral Denture Stomatitis.

Denture stomatitis is a common condition manifested by inflammation of the oral mucous membrane beneath a denture. The objective of this study was to compare the transcriptome of human palatal mucosa with chronic oral stomatitis-associated Candida albicans infection to that of healthy oral mucosa. Oral palatal biopsies were obtained from 17 healthy and 15 C. albicans-infected stomatitis subjects for whole transcriptome analyses. The presence of C. albicans was confirmed by cytology and cultivable methods. The clinical severity of the stomatitis was evaluated by the Newton Classification (Class II or III). For transcriptome analyses a false discovery rate (FDR) of <0.05 was used, and the effects of age, race, and gender were evaluated by principle component analysis (PCA). Specific differentially expressed genes identified by mRNA array data were confirmed by measurements of salivary protein expression using multiplex analyses. Microarray analysis of mRNA expression indicated that in C. albicans stomatitis there were 3034 genes-in-play that were differentially expressed and met the FDR < 0.05 criteria. Two hundred thirty five (235) genes were up-regulated >2-fold, and 71 genes were down-regulated >2-fold. Five of the 6 most significant gene ontology pathways involve inflammation and activation of the immune response with CD28 and CTLA signaling of T cells. There was strong up-regulation of TLR2, CD14, MYD88, IKKA, and NFKB as the dominant toll-like receptor-signaling pathway. The expression of several extracellularly expressed inflammatory protein genes was up-regulated in candidiasis, and 2 were confirmed as up-regulated within the saliva using protein multiplexing analyses. Neutrophil recruitment and activation, epithelial suppression, and T-cell activation appear as major pathways in chronic oral candidiasis. Tissue up-regulation of TLR2 pathways, as well as potential C. albicans binding proteins, was observed, whereas keratin and adhesion molecule synthesis were down-regulated. Several candidate biomarkers to potentially identify the presence of oral candidiasis were differentially expressed in tissues and saliva.

Immune Cells in Different Clinical Presentations of Denture Stomatitis

Denture stomatitis (DS) is a frequent lesion that affects the mucosa covered by a denture, especially in elderly patients. The etiology is multifactorial, but is strongly associated with Candida albicans. We quantified different cells in DS lesions clinically classified as simple or diffuse inflamed mucosa (DS1) or hyperplastic surface (DS2) under a maxillary complete denture (papillary hyperplasia). The molecules CD3, CD4, CD8, CD20, CD68, and mast cell tryptase were labeled by immunohistochemistry in 32 DS cases and 6 healthy human palatal mucosa samples (control) obtained from the files of the Anatomical Pathology Laboratory of FOB/USP.

Human Palatal and Tuberosity Mucosa as Donor Sites for Ridge Augmentation

Since different clinical outcomes of periodontal bilaminar surgeries using the palate or the maxillary tuberosity as connective tissue (CT) donor sites have been observed, tissues grafted with CT from the palate or the tuberosity 1 year after surgical procedures for ridge augmentation were compared with nongrafted tissues by using morphologic and molecular methods. Collagen content and matrix metalloproteinases 1 and 2 expression were similar in tissues and cultured fibroblasts from the palate and tuberosity, although with interindividual differences. In contrast, differences in collagen cross-linking and maturation in the tuberosity fibroblasts were observed, suggesting a possible role in determining hyperplastic responses in some patients.

A Study on the Blood Flow Dynamics in Human Palatal Mucosa under Mechanical Pressure Measured by Temperature Controlled Thermoelectrical Method.

Mucosal blood flow in human palate was measured by a temperature controlled thermoelectric method based on the thermal conductivity of mucosal tissue by means of a blood flow monitor and a noninvasive surface probe.The effect of mechanical pressure on the palatal mucosal tissue was studied. Mechanical pressure (2.5, 5.0, 7.5, 10.0, 12.5 or 15.0gf/mm2) to the mucosal surface was exerted circumferentially around the surface probe by using an acrylic resin cover whose width of mucosal contact area was 1 or 4mm. After releasing the mechanical pressure, blood flow showed a tentative increase above that measured before loading the pressure. The rate of development of this phenomenon increased significantly depending on the amount of the mechanical pressure in each width of the mucosal contact area of the acrylic resin cover. The width difference of the mucosal contact area of the acrylic resin cover was shown to result in a different incline of the regression line for the relationship between the rate of development of the phenomenon and the amount of the pressure. It was suggested that the development rate of the phenomenon might be useful as a p arameter for the analysis of the physiological or mechanical properties of denture supporting tissues.

Effect of mechanical pressure on the blood flow in human palatal mucosa measured by temperature controlled thermoelectrical method.

Mucosal blood flow in the human palate was measured by a temperature controlled thermoelectrical method based on the thermal conductivity of mucosal tissue using a blood flow monitor and a non-invasive surface probe. The effect of mechanical pressure on the palatal mucosal tissue was studied. Mechanical pressure (2.5, 5.0, 7.5, 10.0 or 15.0 g mm-2) to the mucosal surface was exerted circumferentially around the surface probe. In five out of seven subjects, the blood flow showed a tendency to be almost constant under the mechanical pressures which are 10.0 g mm-2 or higher. The effect of the duration of the pressure (10.0 g mm-2) exertion on the blood flow was also investigated and it was revealed that the blood flow tended to be constant after 60s in every subject. In the present study, it was also demonstrated that the temperature controlled thermoelectrical method is appropriate for studying the blood flow dynamics in oral mucosa.

Non-innervated Merkel cells and Merkel-neurite complexes in human oral mucosa revealed using antiserum to protein gene product 9.5

Merkel cells are non-keratinized cells present in many different epithelia, but whose origin and functional role are still controversial. They were here investigated by means of antisera to the neural and neuroendocrine markers protein gene product 9.5 (PGP 9.5), and neurone-specific enolase. The expression of both markers in Merkel cells of human gingival and palatal mucosa was confirmed. Merkel cell-neurite complexes and isolated non-innervated Merkel cells had a similar morphology when stained by either antiserum. Merkel-neurite complexes were clustered in relatively large numbers in the lingual gingiva, thus constituting structures closely similar to the ‘touch domes’ in the skin. Clusters of non-innervated cells showing the same immunohistochemical features as Merkel cells were also demonstrated. In other areas of the oral mucosa, the innervated and non-innervated elements were only occasionally seen but there were many encapsulated Meissner-like receptors. When comparing the two different antisera, anti-PGP 9.5 appeared to provide a more consistent labelling of small fibres inside the epithelium and of bulb-like terminals on Merkel cells.

Immunoelectron microscopy shows an atypical pattern and a quantitative shift of collagens type I, III and VI in oral Kaposi's sarcoma of AIDS

The localization of collagen types I, III and VI in normal human alveolar and palatal mucosa and in oral Kaposi's sarcoma (KS) was studied by light microscopy and cryo-immunoelectron microscopy. Normal oral mucosa revealed two different types of organization. The upper connective tissue stroma contained a loose reticular network mainly composed of collagen types III and VI, while collagen type I immunostaining predominated in the deeper stroma. Ultrastructurally, in the KS tumour stroma, a loose pattern of individual thin collagen fibrils was noted. These often fanned out at their ends showing a filamentous substructure. The fibrils consisted predominantly of collagen type I similar to individual fibrils of normal oral mucosa. However, there was a marked loss of thick fibre bundles of collagen types I and III in KS compared with normal oral mucosa, whereas collagen type VI was markedly increased and found preferentially in clusters and strands around cross-striated fibrils that often spanned the distance between single collagen fibres. The abundance of collagen type VI in a pattern similar to early stages of wound healing suggests that the KS stroma resembles an early organizational stage of the interstitial and vascular extracellular matrix subject to a high rate of collagen turnover. This character of the KS stroma appears to result from a continuous auto-and paracrine stimulation of cell growth and collagen synthesis and provides an excellent model to study the structural arrangement of collagen type VI in relation to the fibrillar collagen types I and III.

Origin of Cells in Human Oral Mucosa Heterotransplants in Nude Mice

Species identification of cells was performed in a model to study epithelial-mesenchymal interactions using combinations of human and murine tissue. The study comprised 34 successfully recovered transplants of human palatal mucosa with 15 human epithelial outgrowths formed on uncertainly species-identified connective tissue. Formalin-fixed and paraffin-embedded 5-micron sections were stained with bisbenzimide (0.8 microgram/ml) and examined in an epifluorescence microscope. The nuclear-staining pattern revealed limited peripheral invasion of the transplanted connective tissue by murine fibroblasts. In areas of epithelial outgrowth a small number of fibroblasts could not be identified but most subepithelial fibroblasts were murine. The study supports previous findings which indicate that the altered differentiation of the human epithelial outgrowths was caused by the murine connective tissue underlying the human epithelium.

Histological localization of myxoid tissue in normal human palatal mucosa and its glycosaminoglycans

Histological localization of myxoid tissue in normal human palatal mucosa and its glycosaminoglycans

Evaluation of replica techniques for the surface ultrastructure of rodent and human palatal mucosa

Two replicating techniques currently used for scanning electron microscopy were investigated qualitatively and quantitatively. The most accurate and reliable replicating material was an epoxy resin; this was superior to copper plating as the model material, despite some dimensional inaccuracies. The selected method was then used to obtain accurate elastomeric replicas of rodent and human palatal mucosa. Salivary-duct openings, epithelial cell boundaries, desquamating cells and cell-surface micropits were identified. In some areas, coccal organisms could be seen colonizing the epithelial surface.

Histological localization of myxoid tissue in normal human palatal mucosa and its glycosaminoglycans

Eighteen specimens of palatal mucosa were taken from 17 human subjects. Paraffin-wax sections were stained by routine methods and with various techniques to demonstrate glycosaminoglycans (GAG). In some sections, GAG were removed by selective degradative procedures before staining. Beneath all rugae, there were myxoid areas varying in size and marginal definition. Collagen fibres were few; elastic and reticulin fibres were numerous in a minority of sections. Alcianophilia at pH 2.5, preventable by streptomyces hyaluronidase digestion, suggested the presence of hyaluronic acid beneath the rugae. Alcian-blue staining at pH 1.0 and with the critical electrolyte concentration method using 0.5 M MgCl 2 did not distinguish the myxoid tissue from the surrounding connective tissue and could be prevented by digestion with testicular hyaluronidase or chondroitinase ABC. Chondroitin sulphate and, or dermatan sulphate thus may be present but were not localized to the myxoid tissue This unusual zone of loose connective tissue may act as a physical buffer resisting the local effects of high loads by allowing reversible extrusion of the water.

Healing following full thickness excision of human palatal mucosa

Healing was observed for 6 months following excision of full thickness normal adult human palatal mucosa (approx 12 mm × 10 mm) to measure the degree of wound contraction and determine if rugae would regenerate. Measurements of plaster models showed stretching and displacement of soft tissue not involved in the original wound toward the centre of the wound from 6 weeks postoperatively. The distance between the incisive papilla and the most posterior ruga on the side of operation reduced by 2.2 mm and the first ruga on the opposite side was stretched in length by 0.9 mm. A fragment of superficial bone (approx 10 mm × 7 mm) sequestrated at 5 weeks, epithelialisation was complete by 8 weeks but the rugae did not reform at all.

Normal keratinized mucosa transplants in nude mice.

Two types of normal keratinized mucosa were transplanted to subcutaneous sites of nude mice of two different strains. 24 intact specimens of clinically normal human palatal mucosa were transplanted to nude mice of the strain nu/nu NC. The transplants were recovered after 42 d with a recovery rate of 96%. Moreover, 22 intact specimens of normal rat forestomach mucosa were transplanted to nude mice of the strain nu/nu BALB/c/BOM. These transplants were recovered after 21 d with a recovery rate of 63%. The histologic features of the transplants were essentially the same as those of the original tissues. However, epithelial outgrowths from the transplants differed with respect to the pattern of keratinization. The outgrowths of human palatal mucosa transplants were essentially unkeratinized, while the outgrowths of the rat forestomach transplants showed continued keratinization.

An investigation of the clinical and histologic effects of selected dentifrices on human palatal mucosa: Andrew L. Allen, Charles E. Hawley, Duane E. Cutright, and Jay S. SeibertJ. Periodontol.46: 102–112, February, 1975

An investigation of the clinical and histologic effects of selected dentifrices on human palatal mucosa: Andrew L. Allen, Charles E. Hawley, Duane E. Cutright, and Jay S. SeibertJ. Periodontol.46: 102–112, February, 1975

An investigation of the clinical and histologic effects of selected dentifrices on human palatal mucosa.

A study was undertaken in 24 human volunteer subjects to determine the possible effects of selected commercially available dentifrices on clinically normal masticatory mucosa. An acrylic stent was fabricated which was designed to hold four test dentifrices in close apposition to the palatal tissues for 1 hour. Evaluation approximately 8 hours later revealed pathologic responses which were evident clinically and histologically. 1. Clinically, palatal tissues exposed to Crest were not distinguishable from control areas, while Colgate (mfp), MacCleans, and Ultra Brite produced erythematous changes which were statistically significant when compared with adjacent control sites. 2. Histologically, epithelial changes were seen within the test sites which ranged from a parakeratin-like surface layer to necrosis and intraepithelial abcess formation. Control sites consisted of normal orthokeratinized palatal mucosa in all cases. 3. The more severe microscopic reactions were noted with MacCleans and Ultra Brite, while the milder reactions were associated with Colgate (MFP). Crest infrequently produced a parakeratin-like response. The response was not statistically significant when compared with controls. 4. The clinical and histologic reactions were generalized throughout the test population, suggesting that the responses were not due to individual hypersensitivity but due to irritation from one or more of the dentifrice components. Although the clinical significance of these findings could not be readily assessed, the potential for irritation of human palatal mucosa by selected dentifrices has been demonstrated. These findings support the suggestion by the World Workshop in Periodontics (1966)20 that efforts should be directed to the development of dentifrice materials less harsh to the oral tissues.

Histological differences in the epithelium of denture-bearing and non-denture-bearing human palatal mucosa

A histological investigation was carried out on palatal biopsies from 40 patients, males, females, denture wearers and non-denture wearers, 10 of each category of individuals being investigated. The material was analysed with different quantitative histological methods and the following observations made. The epithelium-connective tissue interface of the mucosa from denture wearers showed a flattening and a less densely granular stratum granulosum as compared with the non-denture wearers, irrespective of sex. After 4 yr of denture wearing, the denture-bearing palatal epithelium did not show changes in mean thickness in comparison with the controls, but the mitotic index in denture-bearing epithelium appeared to be 3 times higher. The site of the mitoses observed was not only in the basal layer but also very frequently in the stratum spinosum.

Immune adherence with keratinized human oral mucosa and human serum.

abstract – All normal human sera examined have been shown to contain complement‐fixing antibody to an antigen present in stratum corneum of human skin. By immune adherence with human sera and sections of frozen biopsy specimens, the antigen was found to be present in sections of keratotic and parakeratotic areas of human gingiva, tongue, alveolar, buccal, and palatal mucosa. Serum from biopsy donors mediated the adherence reaction. Absorption with a phenol‐water extract (water phase) of stratum corneum of skin removed the antibodies. The antigen was not detected in non‐keratinized areas of human oral mucosa, including gingival crevice and cuff epithelium. Erythrocytes also adhered to keratinized epithelium in gingival biopsy specimens fixed in ethanol and cleared in xylene at 4° C prior to sectioning and incubation with human serum.

Studies on the permeability of human oral mucosa. II. The permeability of dry palatal mucosa to water, sodium and potassium.

The permeability of normal human palatal mucosa after suspended oral secretion was studied in 14 young adults by analysing the increase of weight and the sodium and potassium content in standardized filter paper discs applied to regions with and without visible glands. Samples taken from mucosa without visible glands exhibited a relatively uniform and individually constant increase in weight, the variation in which proved to be a linear function of the relative humidity of the surrounding air during sampling. Samples taken with direct contact between the mucosa and the filter paper regularly contained small amounts of sodium and potassium, and small amounts of desquamated epithelium. Corresponding samples taken with a cytological filter contained no demonstrable traces of the two electrolytes and showed a strong reduction in the number of epithelial cells. The simultaneous samples from the glandular mucosa region showed greater variability in weight increase and content of the two electrolytes, especially of sodium. The results showed a continuous outward diffusion of water and an apparent impermeability to sodium and potassium of the dry palatal epithelium.