Number Of AgNORs Research Articles

Age and AgNor- A Morphometric study

To investigate and correlate total AgNOR area/Total nucleus area (TAA/TNA ) values in buccal epithelial cells of healthy individuals in different age groups. Material and Methodology:- In present study 50 healthy individuals are included with age ranging 10 to 60 years. These are divided into 5 groups.Group1-10-20year, Group2-20- 30year, Group3-30-40year, Group4-40-50year, Group5-50-60year. Oral epithelial cells collected with the help of cyto brush from buccal mucosa. Smears were prepared on clean glass slides and fixed with 95% alcohol. Fixed slides Smears were stained with AgNOR stain. Results: Statistically significant correlations were found between mean TAA/TNA values and age p < 0.001 for linear and p < 0.0001 for polynominal regression, and between AgNOR number and age, p < 0.001 for linear. Conclusion: There is a significant correlation between age and AgNOR amount (ribosome biosynthesis rate) in buccal epithelial cells of healthy individuals. AgNORs in buccal epithelial cells may be used for detection of age.

Does capsaicin have therapeutic benefits in human colon adenocarcinoma? Selection of the most reliable dose via AgNOR

Background/aim To determine the effect of different doses of capsaicin on AgNOR protein synthesis in human colon adenocarcinoma derivate from colon cancer (Caco-2 cell).Materials and methods In this experimental study, after the cultured of Caco-2 cell line, the cells are divided into 4 groups as control and different capsaicin exposed doses (25uµ, 50uµ, and 75uµ). Mean AgNOR number and total AgNOR area/nuclear area (TAA/NA) were calculated.Results A significant differences were detected between control and capsaicin (50uµ) (P = 0.001), between control and capsaicin (75uµ) (P = 0.000), between capsaicin (25uµ) and capsaicin (50uµ) (P = 0.001) and between capsaicin (25uµ) and capsaicin (75uµ) (P = 0.000) for TAA/NA. Also, there were significant differences between control and capsaicin (50uµ) (P = 0.001), between control and capsaicin (75uµ) (P = 0.000), between capsaicin (25uµ) and capsaicin (50uµ) (P = 0.000) and between capsaicin (25uµ) and capsaicin (75uµ) (P = 0.000) for mean AgNOR number.Conclusion: A certain amount of capsaicin has a protective effect against colon adenocarcinoma and the dose concentrations are important for the most reliable treatment.

AgNOR as an effective diagnostic tool for determining the proliferative nature of different types of odontogenic cysts.

Objective:To determine the proliferative nature of different types of odontogenic cysts using silver-stained nucleolar organizer region (AgNOR) staining.Materials and Methods:Forty histopathological sections of each of odontogenic keratocyst, dentigerous, and radicular growth were taken into study. Two sections were produced using the paraffin block of separate cases, one was stained with hematoxylin and eosin and another segment was stained with silver nitrate method.Results:AgNOR staining shows black dots and other parts of nuclei show yellow-brown dots.Conclusion:AgNOR, which stain for NOR-related proteins, corresponds to cell multiplication. Their amount regarding the number of AgNORs per cyst can be a good marker of the proliferative action of the cell in aggressive cystic lesion having malignant potential.

Cytogenetic characterization of Hypostomus soniae Hollanda-Carvalho & Weber, 2004 from the Teles Pires River, southern Amazon basin: evidence of an early stage of an XX/XY sex chromosome system.

In the present study, we analyzed individuals of Hypostomus soniae (Loricariidae) collected from the Teles Pires River, southern Amazon basin, Brazil. Hypostomus soniae has a diploid chromosome number of 2n = 64 and a karyotype composed of 12 metacentric (m), 22 submetacentric (sm), 14 subtelocentric (st), and 16 acrocentric (a) chromosomes, with a structural difference between the chromosomes of the two sexes: the presence of a block of heterochromatin in sm pair No. 26, which appears to represent a putative initial stage of the differentiation of an XX/XY sex chromosome system. This chromosome, which had a heterochromatin block, and was designated proto-Y (pY), varied in the length of the long arm (q) in comparison with its homolog, resulting from the addition of constitutive heterochromatin. It is further distinguished by the presence of major ribosomal cistrons in a subterminal position of the long arm (q). The Nucleolus Organizer Region (NOR) had different phenotypes among the H. soniae individuals in terms of the number of Ag-NORs and 18S rDNA sites. The origin, distribution and maintenance of the chromosomal polymorphism found in H. soniae reinforced the hypothesis of the existence of a proto-Y chromosome, demonstrating the rise of an XX/XY sex chromosome system.

Dynamics of morphofunctional activity of blood lymphocytes of Stavropol breed sheep in postnatal ontogenesis and during pregnancy

The aim of the paper was to study the activity of nucleolar organizer zones of blood lymphocytes of Stavropol breed sheep in postnatal ontogenesis and during pregnancy. Blood smears for cytomorphology studies were painted with silver nitrate and subsequent additional coloring with azure and eosin. By measuring the parameters of the nucleus and parameters of the activity of nucleolar organizers (AgNORs), the changes in the morphofunctional state of the protein-synthesizing apparatus of blood lymphocytes in sheep of Stavropol breed in postnatal ontogenesis were evaluated. It was found that newborn lambs’ area of the nuclei of lymphocytes was 76.50 ± 2.30 µm2. By the age of three months, the area of lymphocyte nuclei in sheep significantly increased by 6.08% and amounted to 81.46 ± 2.45 µm2, and did not change significantly until the age of twelve months. The number of units of argentophilic nucleolar organizers in the nuclei of lymphocytes (AgNORs) is from 1 to 4. The average area of AgNORs in the nuclei of lymphocytes is in the range from 73.60 ± 2.45 up to 80.10 ± 2.41 µm2. In sheep of Stavropol breed on the 90th day of pregnancy, the area of the nucleus of lymphocytes was 68.70 ± 2.15 µm2. By 135 days of pregnancy, a significant decrease in the area of the nuclei of the lymphocytes by 14.66% was found. After childbirth, there was a slight decrease in the area of lymphocytes in sheep compared to the previous period of research. During pregnancy, sheep were found to have from 1 to 3 AgNORs with a total area from 0.70 ± 0.11 to 2.93 ± 0.43 µm2. On the basis of the conducted studies, it can be concluded that in postnatal ontogenesis and during pregnancy of sheep, the functional state of lymphocytes changes, this is manifested in changing the parameters of the area of their nuclei, the number and total area of AgNORs.

Cytogenetic instability of chromosomal nucleolar organizer regions (NORs) in cloned mouse L929 fibroblasts.

Ribosomal DNA (rDNA) gene codes for 18S, 5.8S, and 28S rRNA form tandem repetitive clusters, which occupy distinct chromosomal loci called nucleolar organizer regions (NORs). The number and position of NORs on chromosomes are genetic characteristics of the species although within a cell, the NOR sizes can significantly vary due to loss or multiplication of rDNA copies. In the current study, we used mouse L929 fibroblasts, the aneuploid cells which differ in the FISH- and Ag-NOR numbers, to examine whether the parental NOR variability is inherited in clones. By statistical analysis, we showed that the cloned fibroblasts were able to restore the NOR numerical characteristics of the parental cells after long-term culturing. These results support the idea that mammalian cells may have mechanisms which control the number and activity of NORs at the population level. In L929 fibroblasts, we also regularly observed laterally asymmetry of FISH-NORs that evidenced in an unequal distribution of the mother rDNA copies between the daughter cells in mitosis.

Nucleolar organizer region banding in crossbred and non-descript pigs of India.

Aim:The objective of this experiment was to study the nucleolar organizer region (NOR)-banding pattern in Large White Yorkshire (LWY) crossbred and non-descript pigs and finding differences in the number of NORs between animals and between genetic groups.Materials and Methods:The experiment was carried out on 15 females, and 15 males of LWY crossbred and non-descript pigs to study NOR-banding pattern by employing ammoniacal silver staining technique.Results:A total of 63 and 65 number of good metaphases were prepared in LWY crossbred, and non-descript pigs and a total of 168 and 143 number of NORs were detected on the 8th and 10th chromosomes in both genetic groups, respectively. The mean number of NORs per metaphase was 2.67 and 2.20 in LWY crossbred and non-descript pigs, respectively. LWY crossbred pig had high mean number of silver-stained NORs (Ag-NORs) per metaphase compared to non-descript pig. In general, it was observed that the highest frequency of metaphases (%) examined had two number of NORs, while the lowest frequency (%) had four number of NORs. The number of NORs observed per metaphase on secondary constrictions of the 8th and 10th chromosome pair in both genetic groups ranged from 2 to 4. The Chi-square test of significance revealed that the observed frequencies do not differ significantly from the expected frequencies.Conclusion:The results confirmed differences across breeds in occurrence and number of NORs on chromosomes in pigs. The mean numbers of NORs present per metaphase vary between the animals indicating the existence of polymorphism for the number of NORs. A higher number of Ag-NORs were observed on chromosome pair 10 in both the genetic groups. It was concluded that NORs were more morphologically distinct and greater on chromosome pair 10 than on pair 8, which suggests a dominant role of chromosome 10 in the global production of ribosomal RNA.

Characterization of eight species of Aloe (Asphodelaceae) from the nucleolar organizing region

Abstract Nucleolar organizing region of eight species of Aloe was analyzed in somatic metaphases and interphase nuclei. All species showed a uniform 2n=14, with eight large chromosomes and six small chromosomes. Satellites were observed on the long arm of one or two pairs of large chromosomes and/or on the short arm of one of the small pairs. The silver-stained nucleolus organizing regions were located on the subtelomeric region of the long arm of one or two pairs of large chromosomes, except for Aloe dichotoma and Aloe maculata, which the AgNORs were located at a short arm of one of their small chromosomes. In most studied species, the active AgNOR number was four. However, this number changing from one to eight. For all species, the interphase number of nucleoli can be one or two, while, in Aloe excelsa, this number can be changing from one to eight. Polymorphism of active AgNORs and the number of interphase nucleoli were revealed, except for Aloe petricola, which active AgNORs were located only in the subtelomeric regions at the long arm of one of the L2 chromosomes, as well as in the L4 pair, which is agrément with the maximum number (three) of interphase nucleoli.

Effects of Diabetes and Hypertension on Oral Mucosa and TGFβ1 Salivary Levels.

in this cross-sectional study, whole stimulated saliva and oral mucosa exfoliative cytology specimens were collected from 39 patients that were healthy (control, n=10) or presented history of arterial hypertension (HAS, n=9), diabetes mellitus (DM, n=10) or both (DM+HAS, n=10). Salivary flow rate (SFR), TGFβ1 level in saliva, AgNORs and the epithelial maturation were evaluated. Non-parametric Kruskal-Wallis test, followed by Dunn's multiple comparison post-test and the Spearman test correlation analysis were used. SFR showed a significant decreased in DM and DM+HAS (0.47±0.11 and 0.64±0.43 mL/min) when compared to control (1.4±0.38 mL/min). DM+HAS presented the highest value of TGFβ1 concentration (24.72±5.89 pg/mL). It was observed a positive correlation between TGFβ1 and glycaemia (R=0.6371; p<0.001) and a negative correlation between TGFβ1 and saliva (R=-0.6162; p<0.001) and glycaemia and SFR (R=-0.5654; P=0.001). AgNORs number and status of maturation of mucosa cells were similar for all conditions. DM and DM+HAS presented the lowest SFR, which correlated with increased TGFβ1 levels. Despite the higher TGFβ1 secretion it was not observed changes in the morphology or proliferation of epithelial cells when diabetes or hypertension was present.

Determination of Proliferative Activity of Neoplastic Cells by Ki67 and AgNOR Staining in Ovine Pulmonary Adenocarcinoma Affected Lungs

Ovine Pulmonary Adenocarcinoma (OPA) is a natural lung cancer of the sheep caused by Jaagsiekte Sheep Retrovirus (JSRV). In the present study, 17 OPA affected lung samples were subjected to histopathological, histochemical and immunohistochemical studies. Grossly, lungs revealed diffuse areas of consolidation or tumor nodules and histologically lung sections showed proliferation of alveolar epithelial cells that were arranged in papillary or acinar pattern. The lung sections were further subjected to immunohistochemical staining for cytokeratin and Ki-67. The proliferative activity of tumor cells was determined by Ki67 and AgNor staining and the mean value of Ki-67 index was 9.53 + 1.88. The mean number of AgNORs for all the cases ranged from 6.5 to 11.9 with a mean + standard deviation values of 9.2 + 1.2. The mean values of Ki-67 index and AgNOR staining were increased in the sections of lung tumor than the normal lung sections indicating the increased proliferative activity of lung tumor epithelial cells.

Cell proliferation markers at the invasive tumor front of oral squamous cell carcinoma: comparative analysis in relation to clinicopathological parameters of patients.

Objectives To evaluate the number of AgNORs per nucleus and the expression of Ki-67 at the tumor invasion front (TIF) in relation to clinical parameters (TNM), TIF classification and the prognosis of oral squamous cell carcinomas in an Uruguayan population.Material and Methods This study was conducted through a retrospective survey from 2000 to 2010 at the National Institute of Cancer Montevideo, Uruguay and included 40 patients. The samples were obtained from the resection of the tumor and the TIF was defined according with Bryne, et al.5 (1992). Expression of Ki-67 was assessed by the percentage of positive tumor cells and the AgNOR was recorded as the mean AgNOR (mAgNOR) and the percentage of AgNOR per nucleus (pAgNOR). All analyzes were performed by a blinded and calibrated observer.Results No statistically significant association was observed between immunostaining of Ki-67 and AgNOR with the different types of TIF, regional metastasis and patients prognosis, however it was observed an increase in Ki-67 expression associated with worse patient’s clinical staging, although not statistically significant.Conclusions Our results suggest that proliferation markers as AgNOR and Ki-67 are not prognostic markers at the tumor invasive front of carcinoma of oral squamous cell.

May argyrophilic nucleolar organizing region-associated protein synthesis be used for selecting the most reliable dose of drugs such as rhamnetin in cancer treatments?

Rhamnetin is a flavonoid that has antioxidant, anti-inflammatory and anti-cancer effects. Nucleolar-organizing regions are the ribosomal genes region. We aimed to identify whether rhamnetin has an effect on cell proliferation and whether AgNOR proteins may be used for the detection of therapeutic benefits of the drugs and new metabolites, which have the potential of being used for cancer treatments. Twenty-four mice with Ehrlich's ascites carcinoma (EAC) were randomly assigned to three main groups as positive control, and groups 2 and 3 treated intraperitoneally with rhamnetin (100 µg/kg and 200 µg/kg, respectively). All the animals were sacrificed on day16, 24 h after the last dose; the tumors, which developed at the site of injection were removed. Then, mean AgNOR number and total AgNOR area/nuclear area (TAA/NA) were detected for each mouse. Significant differences were detected among all groups for mean AgNOR number (p = 0.000) and TAA/NA ratio (p = 0.000). While the difference between positive control and Rhamnetin (100 µg/kg) group was not significant (p = 0.387), there are significant differences between positive control and Rhamnetin (200 µg/kg) group (p = 0.000) and between Rhamnetin (100 µg/kg) and Rhamnetin (200 µg/kg) groups (p = 0.000) for TAA/NA ratio. Rhamnetin has an important role in preventing cancer formation. Our study showed that mean AgNOR numbers and TAA/NA values may be used also as biomarkers for evaluating the success rate of the performed therapeutic strategy and accurate dose selection for the management of the disease (Tab. 3, Fig. 3, Ref. 45).

The detection of curcumins' antitumoral effects via argyrophilic nucleolar organizing region-associated protein synthesis in mice with ehrlich's ascitic carcinoma.

Curcumin is a polyphenol compound that has antioxidant, anticancer, anti-inflammatory, anti-hyperlipidemic and antimicrobial effects. Nucleolar-organizing regions are the sites of the gene on chromosomes. The present study was aimed to show the antitumoral effect of curcumin via AgNOR protein synthesis in Ehrlich's ascitic carcinoma (EAC) bearing mice. Twenty three mice with EAC were randomly divided into 3 groups as positive control (n = 7), group 2 (n = 8) and 3 (n = 8) treated intraperitoneally with curcumin (25 mg/kg) and (50 mg/kg), respectively. The animals were sacrificed on Day 16, the solid tumors were removed out. Then, total AgNOR area/nuclear area (TAA/NA) and the mean AgNOR number were estimated for each mice. Statistically significant differences were determined among the whole groups for TAA/NA ratio (p = 0.000), conversely mean AgNOR number (p = 0.361). When comparingthe two groups; while no difference was determined between the control and curcumin (25 mg/kg) groups (p = 0.061), the significant differences were detected between the control and curcumin (50 mg/kg) groups (p = 0.000) and between curcumin (25 mg/kg) and curcumin (50 mg/kg) groups (p = 0.000) for TAA/NA ratio. However, there was no significant difference for the mean AgNOR number in double comparison of the groups. The current study showed that curcumin had a crucial function against cancer development. Also, both AgNOR values might be used as biomarkers for detection of the most reliable therapeutic dose selection of cancer treatment (Tab. 3, Fig. 2, Ref. 27).

How Useful is the AgNOR Staining Method for the Diagnosis of Salivary Gland Tumors?

Objectives: The purpose of this study was to determine the numbers and mean areas of the AgNOR dots in the 3 most common salivary gland tumors. Materials and Methods: One hundred and seventy paraffin blocks histologically diagnosed as pleomorphic adenoma, adenoid cystic carcinoma, and mucoepidermoid carcinoma were selected from the archives of the pathology department of Loghman hospital, Tehran, Iran and then cut and stained using the standard AgNOR method. The number and area of AgNOR dots were evaluated. Chi-square and Pearson correlation (2-tailed) tests were used for statistical analysis. The significance level was P < 0.05. Results: The chi-square test showed significant differences between tumor types and the numbers of AgNORs (P = 0.000) and between tumor types and areas of AgNORs (P = 0.000). Conclusions: The AgNOR technique can be used to diagnose salivary gland tumors.

The role of determining the nucleolar organizers in assessing the evolution of neoplasms

Background Nucleolar organizer regions are parts of chromosomes that code ribosomal RNA and correlate to cellular proliferation. They have been identified by means of an argyrophilic technique that reveals NORs as black dots in the nuclei. The method has been recently applied in some malignancies, as lymphoma or melanoma. Only few investigations on hormonal-dependent tumours have been published. Our aim was to investigate on the total number of AgNORs and cell type of endometrial tumors. Material and Methods We studied 21 cases of formalin fixed paraffin embedded endometrial tumors including hyperplasia. The number of AgNORs was counted in both epithelial and stromal components. A total of 13 cases were benign and 8 malignant lesions. Results The total number of AgNORs was found to correlate with mitotic counts both in benign lesions and malignancies. The mean number of AgNORs increased from 2.79 in simple endometrial hyperplasia to 10.0 in adenocarcinoma. Conclusions Our data indicate that the AgNORs visualization can assist to differentiate between different malignancy grades of endometrial proliferations, especially between complex endometrial hyperplasia and atypical hyperplasia as well as endometrial adenocarcinomas.

Adverse effects of aflatoxin B1 on skeletal muscle development in broiler chickens

1. Detrimental effects of in ovo administrated of aflatoxin B1 (AFB1) on the embryonic development of skeletal muscle were determined using histological methods.2. A total of 420 eggs of a Ross broiler parent stock were incubated and divided into 4 groups: (1) control, (2) 5 ng AFB1/egg group, (3) 15 ng AFB1/egg group, (4) 40 ng AFB1/egg group. Test solutions were injected via the air-sac, just prior to setting the eggs in the incubator.3. Five eggs from each group were opened on different days of incubation (11d, 13d, 17d and 21d). Developmental stages of embryos were determined according to the Hamburger–Hamilton scale and embryos were weighed. Skeletal muscle tissue samples were dissected and fixed, sectioned and stained with Crossman’s trichrome and AgNOR.4. The mean relative embryo, leg muscle and breast muscle weights of AFB1-treated groups were lower than the control group and decreased with increasing AFB1. The nucleus area and AgNOR area of the AFB1-treated groups were also lower than the control group whereas there were no significant differences in AgNOR numbers and AgNOR area/nucleus area among the treatment groups.5. It was concluded that in ovo administrated of AFB1 adversely affected the embryonic development of skeletal muscle and that affected animals might therefore be more susceptible to skeletal and muscle disorders during the growing period.

Reduction of the argyrophilic nucleolar organizing region associated protein synthesis with age in buccal epithelial cells of healthy individuals.

Nucleolus organizer regions (NORs) consist of the rRNA coding gene family (rDNA) in the cell nucleus. The argyrophilic proteins are selectively stained with silver nitrate and bind these regions. It was reported that NOR (rDNA) activity decreases in human lymphocytes, fibroblasts and bone marrow with age. However, to our knowledge there have not been any studies related to the NORs in oral epithelial cells of healthy individuals. Our aim is to detect any correlation between age and Total AgNOR area/Total nucleus area (TAA/TNA) values in buccal epithelial cells of healthy individuals. Oral epithelial cells from 50 healthy individuals (age range of 2-80 years old) were spread onto a clean glass slide, air dried and fixed. Then the AgNOR staining protocol was performed on these cells. TAA/TNA ratio and AgNOR dots were calculated using software. From each person 50 oral epithelial cells were evaluated. Statistically significant correlations were found between mean TAA/TNA values and age (Rsq = 0.534, p < 0.001 for linear and Rsq = 0.728, p < 0.0001 for polynominal regression), and between AgNOR number and age (Rsq = 0.621, p < 0.001 for linear and Rsq = 0.693, p < 0.0001 for polynominal regression). There is a significant correlation between age and AgNOR amount (ribosome biosynthesis rate) in buccal epithelial cells of healthy individuals. AgNORs in buccal epithelial cells may be used for detection of age.

Exfoliative cytology as a tool for monitoring pre-malignant and malignant lesions based on combined stains and morphometry techniques.

Prevention and early diagnosis have the greatest potential for public health and are the most effective method in the long-term to control oral cancer. The aim was to apply PAP staining together with AgNOR staining and morphometric analysis in oral exfoliative cytology, to determine the sensitivity and specificity of these methods in the detection of malignant changes for the purposes of both initial population monitoring and follow-up. AgNOR, Papanicolau, and morphometric tests were conducted in samples of patients with oral cancer, oral potentially malignant disorders and controls (opposite side of lesions). Specificity and sensitivity values for each stain method and the curve under ROC area were estimated. The diagnostic variables which allowed greatest accuracy in identifying malignancy relative to the healthy control were cluster (76.92%), satellite (75.64%), and total (90%). The diagnosis was seen to be associated with PAP and total AgNOR, total AgNOR and PAP, total AgNOR and satellites and clusters, and total AgNOR nuclear area/cytoplasmic area ratio. The total number of AgNOR is a reliable marker for detecting neoplastic cells; this method increases sensitivity and specificity by decreasing the likelihood of false negatives or positives, as the accuracy obtained was 90%. It is also a low-cost, non-invasive, simple methodology that can be recommended to help the early detection of oral cancer and monitoring of patients with a first diagnosis of cancer.

Differential rRNA genes expression in bread wheat and its inheritance

The expression of the ribosomal RNA (rRNA) genes from rye, located within the nucleolus organizer regions (NORs), is repressed by cytosine methylation in wheat x rye hybrids and in triticale, as consequence of nucleolar dominance. Our previous study revealed that bread wheat cultivars with a maximum number of four Ag-NORs presented high level of rDNA cytosine methylation when compared to others with a maximum of six Ag-NORs. In order to evaluate the inheritance of the Ag-NORs number and NOR methylation patterns, we produced F1 hybrids between bread wheat cultivars with four Ag-NORs and bread wheat cultivars with six Ag-NORs (in the direct and reciprocal senses). The F2 progenies of these F1 hybrids were also evaluated for the NOR number and methylation patterns. Parent bread wheat cultivars with a maximum of four Ag-NORs after treated with 5-azacytidine evidenced a maximum of six Ag-NORs per metaphase cell and a maximum of six nucleoli per interphase nucleus, confirming that the expression of the rRNA genes in bread wheat is related to cytosine methylation. Most of the F1 hybrids showed a maximum number of four or six Ag-NORs, similarly to that of the female parent suggesting a non-mendelian inheritance, while other hybrids presented four or six Ag-NORs in both senses of the cross. The F1 NOR methylation patterns showed some fragments common to their parents but also novel fragments suggesting genomic and/or chromosome rearrangements after hybridization. Despite the different NOR patterns among the parents, an invariable NOR pattern was found among the F1 plants suggesting a tendency to stability, which was also transmitted to the F2. The F2 progenies showed plants with a maximum of four, five and/or six Ag-NORs. The ratio of plants with four, five and/or six Ag-NORs per F2 progeny was variable and did not follow any specific mendelian proportion. These results allowed us to suggest that the inheritance of the number of Ag-NORs by the F1 and F2 plants did not follow any mendelian inheritance and were not correlated to NOR methylation patterns in contrast to what was verified for their parents.

Cellular proliferation markers in peripheral and central fibromas: a comparative study

Objective:To perform a comparative study of the cellular proliferation in the peripheral and central fibromas. Material and Methods:Immunohistochemistry for PCNA and the AgNOR technique were performed in 9 cases of peripheral odontogenic fibroma (POF), in 4 cases of odontogenic fibroma (OdF), in 8 cases of peripheral ossifying fibroma (PEOF) and 7 cases of ossifying fibroma (OsF). The Kruskal-Wallis and Mann-Whitney tests were used for the statistical analyses. Results:Mesenchymal component of the central lesions presented a higher mean number of AgNOR per nucleus and PCNA index than did the peripheral lesions (P≤0.05). The mean number of AgNOR per nucleus in the epithelial component proved to be higher in the OdF than in the POF (P≤0.05). The mesenchymal and epithelial components presented similar mean numbers of AgNOR per nucleus and PCNA index in the OdF, as well as a similar mean number of AgNOR per nucleus in the POF.Conclusions:The mesenchymal component may well play a role in the differences between the biological behaviour of the central lesions as compared to the peripheral lesions. Moreover, considering that the epithelial and mesenchymal components in odontogenic fibromas presented a similar proliferation index, more research is warranted to understand the true role of the epithelial components, which are believed to be inactive in nature, as well as in the development and biological behaviour of these lesions.