Mean Number Of Nucleoli Research Articles

Effects of Non-Opiate Analogue of Leu-Enkephalin on the Ion Currents, Number of Nucleoli, and p53 Expression in Isolated Cardiomyocytes of Albino Rats.

Acute exposure of isolated ventricular cardiomyocytes to non-opiate analogue of leu-enkephalin (NALE peptide: Phe-D-Ala-Gly-Phe-Leu-Arg) in a concentration of 100 μg/liter and 6-h incubation in NALE solution did not significantly change ATP-dependent K+ current, L-type Ca2+ current, p53 protein expression, and number of nucleoli in the cardiomyocyte nuclei. Incubation of cardiomyocytes with NALE (100 μg/liter) in combination with NOP receptor blocker J-113397 (1 mg/liter) was followed by an increase in Ca2+ L-type current and the number of p53+ cells. The exposure of cardiomyocytes to NALE in a concentration 1000 μg/liter induced similar changes in the studied parameters (increase in Ca2+ L-type current and number of p53+ cardiomyocytes); an increase in the mean number of nucleoli was also observed. Our findings suggest that NALE peptide has direct effect on cardiomyocytes and NOP receptors are involved in this effect.

Evaluation of Nuclear Parameters in Relation to Regional Lymph Node Involvement in Oral Squamous Cell Carcinoma: A Cytomorphometric Study

Background: Up-regulation of ribosome biogenesis encodes the factors related to carcinogenesis. It has been shown that the nucleus diameter and number of nucleoli increase from normal mucosa to oral squamous cell carcinoma (OSCC). The relationship between nuclear parameters and lymph node involvement in OSCC has not been established, yet. The aim of this study was to evaluate the nuclear parameters comprising nucleoli count and nucleus: nucleoli ratio in relation to regional lymph node involvement in OSCC. Methods: Thirty-four formalin-fixed, paraffin embedded sections from different histopathologic grades of OSCC were stained with methyl green-pyronin. Mean number of nucleoli and nucleus: nucleoli ratio were calculated in 100 tumor cells from 10 random selected fields and compared based on lymph node involvement. Results: Nucleoli count in cases with metastasis to regional lymph nodes was not significantly different from that in cases without regional lymph nodes involvement (P=0.29). The difference of nucleus: nucleoli ratio in cases with and without lymph nodes involvement were not significant (P=0.52). No significant correlation was found between the nucleoli count and lymph node involvement (r=0.08, P=0.78). The correlation between nucleus: nucleoli ratio and lymph node involvement was significant (r=0.58, P=0.02). Conclusion: The nucleus: nucleoli ratio of tumoral cells in OSCC was correlated to lymph node involvement. Based on the results, nucleus: nucleoli ratio can potentially be a useful tool to determine the lymph node involvement in OSCC.

Behavior of Human Dental Pulp Cells Exposed to Transforming Growth Factor-Beta1 and Acidic Fibroblast Growth Factor in Culture

The development of methods for regenerative endodontic procedures requires an understanding of the factors regulating the development of odontoblasts from adult cell populations such as pulpal cell lines. In this study, we exposed cultures of human pulp cells (7th passage) to growth factors including transforming growth factor-beta1 (TGF-beta1, at 1 or 5 ng/mL), acidic fibroblast growth factor (aFGF, 5 ng/mL), or a combination of the 2 growth factors and evaluated cellular morphology and markers of cell phenotype including alkaline phosphatase activity, osteocalcin, bone sialoprotein (BSP), and dentin sialophosprotein (DSPP). The mean number of nucleoli in the 1 ng/mL TGF-beta1 group was significantly higher than with 5 ng/mL aFGF. Alkaline phosphatase activity was significantly greater with 1 ng/mL TGF-beta1 versus 5 ng/mL TGF-beta1 + 5 ng/mL aFGF (P < .05). Osteocalcin mRNA was expressed in all samples. The cells exposed to 1 ng/mL TGF-beta1 were stimulated; however, exposure to growth factors for 8 days was not sufficient for expression of BSP and DSPP mRNA. Cells treated with 1 ng/mL TGF-beta1 exhibited higher activity, whereas 5 ng/mL aFGF-treated cells were inhibited. Although osteocalcin was observed in all cultures, suggestive of the potential for odontoblast formation, under the present conditions, the exposure to TGF-beta1 and aFGF was not sufficient to induce expression of the dentin matrix components BSP and DSPP.

Morphofunctional changes in neurons of hippocampal fields and neocortical layers in rats treated with Polydan.

Light microscopy revealed four types of neurons differing by staining intensity and size in each of the pyramidal neuron populations in the dorsal hippocampal fields and layer V of the neocortical somatosensory area and in granular cells of the dentate fascia and stellate cells of layer II of the same cerebrocortical area in rats. Treatment with Polydan according to different protocols led to redistribution of these types of cells, which attests to stimulation of synthetic processes in these brain areas, rather than to similar sequence of the involvement of different brain areas in this process. Polydan promoted the increase in the mean number of nucleoli in the nuclei of neurons of all types, the degree of this increase being different for each type. It seems that morphological signs (staining intensity and number and size of nucleoli in the nuclei) reflect certain functional states of the neurons in the homogeneous populations. Presumably, various factors can stimulate transition of neurons from one morphofunctional status into another.

Neuronal body size correlates with the number of nucleoli and Cajal bodies, and with the organization of the splicing machinery in rat trigeminal ganglion neurons.

Trigeminal ganglion neurons comprise three main cell body-size types. This cell size heterogeneity provides an excellent neuronal model to study the cell size-dependent organization and dynamics of the nucleoli, Cajal (coiled) bodies (CBs), and nuclear speckles of pre-mRNA splicing factors, nuclear structures that play a key role in the normal neuronal physiology. We have analyzed the number of nucleoli and CBs and the structural and molecular organization of CBs and nuclear speckles in the three neuronal types by using immunofluorescence with antibodies that recognize nucleoli (fibrillarin), CBs (coilin), and nuclear speckles (snRNPs), confocal microscopy, and electron microscopy. Whereas the mean number of nucleoli per neuron decreases as a function of cell size, the number of CBs per cell significantly increases in large neurons in comparison with the small ones. In addition, large neurons have a higher proportion of CBs associated with the nucleolus. In all neuronal types, CBs concentrate coilin, fibrillarin, snRNPs, and the survival motor neuron protein (SMN). Immunostaining for snRNPs shows small speckle domains and extensive areas of diffuse nucleoplasmic signal in large neurons, in contrast with the large nuclear speckles found in small neurons. Furthermore, flow cytometric analysis shows that all neurons are in the range of diploid cells. These findings indicate that the fusion behavior of nucleoli, the formation of CBs and their relationships with the nucleolus, as well as the compartmentalization of the pre-mRNA splicing machinery, is related to cell body size in the trigeminal ganglion neurons. Because transcriptional activity is a basic determinant mechanism of cell size in diploid cells, we suggest that our findings reflect a distinct transcription-dependent organization of the nucleolus and splicing machinery in the three cell types of trigeminal ganglion neurons.

Ploidy Level Determination in Genetically Manipulated Northern Pike Based on the Number of Active Nucleoli per Cell

Abstract Silver-staining of cell preparations followed by counting of the mean number of active nucleoli per cell enabled determination of the ploidy level in genetically manipulated northern pike Esox lucius. Haploid pike resulted from activation of eggs with sperm irradiated with ultraviolet light, and triploid specimens were obtained by applying high-temperature shock. Cells of haploid individuals had one (almost 100% of cells examined) or, sporadically, two nucleoli. Depending on the specimen, mean number of nucleoli per nucleus ranged from 1.0 to 1.06. In diploid fish, the mean number of active nucleoli per cell ranged from 1.58 to 1.81. In triploids, the mean ranged from 2.08 to 2.46. Positive identification of ploidy level in northern pike required examination of up to 40 cells per individual, as determined by the regression analysis. The method required a very small amount of any kind of tissue, enabling determination of ploidy level in juvenile fish without sacrificing them.

Nucleolar coefficient and cytochemistry of human blood monocytes

Nucleoli in peripheral blood monocytes represented mostly by micronucleoli were investigated by means of cytochemical procedures for the demonstration of RNA, proteins of silver stained nucleolus organizer region, nucleophosmin, nucleolin and fibrillarin. The values of the nucleolar coefficient (mean number of nucleoli per cell) were influenced by the procedure used for the visualization of nucleoli. The differences in the values of the nucleolar coefficient of monocytes in one and the same person using above mentioned procedures suggested that micronucleoli in blood monocytes represent heterogeneous nuclear structures and only some of them possess both RNA and characteristic nucleolar proteins. Therefore, the procedures used for the visualization of nucleoli must be always taken into consideration when the values of the nucleolar coefficient are evaluated.

Ploidy Level Determination in Genetically Manipulated Bream, Abramis brama, Based on the Number of Active Nucleoli Per Cell

ABSTRACT Ploidy level on genetically manipulated bream, Abramis brama, was determined using the mean number of silver staining nucleoli per cell. Haploid bream resulted from activation of eggs with UV-irradiated sperm, and triploid specimens were obtained by applying cold-temperature shock. Cell preparations were made for 20 fish of each ploidy level: IN, 2N, and 3N. The frequency of one, two, and three nucleoli per cell were calculated based on observation of 200 cells per studied individual. Cells of haploid individuals had one or, sporadically, two nucleoli, and depending on the specimen, mean number of nucleoli per nucleus ranged from 1.0 to 1.02; cells of diploid fish had one, two, or, sporadically, three nucleoli with the mean ranging from 1.70 to 1.76; in triploids there were one, two, or three nucleoli per cell, with the mean ranging from 2.15 to 2.41. Positive identification of ploidy level in bream requires examination of no more than 40 cells per individual, as has been determined by regression analysis. The method requires very small amounts of any kind of tissue, enabling determination of ploidy level in juvenile fish without sacrificing the fish.

Number of Nucleoli and Nucleolar Organizer Regions per Nucleus and Nucleolus — Prognostic Value in Canine Mammary Tumors

Twenty-eight canine mammary tumors were evaluated for histopathologic classification as recommended by the World Health Organization and silver-binding nucleolar organizer region (AgNOR) and nucleolus counts. Samples of surgically excised tumors and tumors taken at necropsy were fixed in neutral formalin, embedded in paraffin, and cut into 1-3-microns-thick sections. Two sections were taken from each tumor: one was stained with hematoxylin and the other was treated with the silver staining technique for the demonstration of AgNORs. After histopathologic classification, the number of nucleoli and the number of AgNORs/nucleus and AgNORs/nucleolus were determined. Statistical analysis (Student's t-test) showed a significant difference in the mean number of nucleoli (P < 0.005), mean number of AgNORs/nucleolus (P < 0.001), and mean number of AgNORs/nucleus (P < 0.005) between benign and malignant canine mammary tumors. There was no significant differences between metastatic and nonmetastatic malignant tumors.

Effects of cycloheximide on the structural organization of the nucleolus and the coiled body in normal and stimulated supraoptic neurons of the rat

This study was designed to determine the effects of cycloheximide, a protein synthesis inhibitor that interferes with rRNA synthesis and processing, on the nucleoli and coiled bodies of supraoptic nucleus neurons from normally-hydrated and osmotically-stimulated rats. The number of nucleoli and the nucleolar size were estimated on smear preparations of previously silver-impregnated supraoptic nucleus. No significant differences were registered in the mean number of nucleoli per cell in cycloheximide-treated rats. The number of nucleoli per neuron remained constant, at about 1.3, in all animal groups, suggesting that the nucleoli number is strictly regulated in differentiated neurons. By contrast, a significant reduction in the average nucleolar volume of supraoptic nucleus neurons was detected in cycloheximide-treated groups of rats in comparison with their equivalent non-treated groups. By electron microscopy, most nucleoli and coiled bodies of supraoptic nucleus neurons exhibited cycloheximide-induced alterations in their fine structure and configuration. Nucleolar changes included the occurrence of a few large fibrillar centres, the formation of microspherules and small intranucleolar vacuoles or dilated interstices, and the partial segregation of nucleolar components coupled with the transformation of reticulated nucleoli--a nucleolar configuration characteristic of supraoptic nucleus neurons of non-cycloheximide-treated rats--into compact ones. The redistribution of nucleolar components might reflect the interference with rDNA transcription, and also supports the hypothesis that the normal assembly of these components into the nucleolus depends upon ongoing nucleolar transcription. Concerning coiled bodies, most of them revealed ultrastructural alterations, particularly segregation of the amorphous matrix, compactation of coiled threads and formation of coiled body-derived dense bodies of fibrillar nature. Moreover, cycloheximide also induced the formation of smaller dense bodies--here referred to as dense microbodies--which presumably represent a distinct nuclear entity different from coiled bodies. Ultrastructural silver staining of nuclear bodies showed a selective silver reaction on the dense fibrillar component of normal and altered coiled bodies, as well as on the dense microbodies. The possible relationship between the nucleolus and both coiled bodies and dense microbodies is discussed.

Benign, borderline, and well-differentiated malignant intestinal mucinous tumors of the ovary: a clinicopathologic, histochemical, immunohistochemical, and nuclear quantitative study of 57 cases.

Mucinous ovarian tumors are still a subject of controversy because they can show either intestinal or endocervical differentiation. Morphologic distinction between borderline and malignant tumors is sometimes difficult, and their clinical behavior has not been definitively ascertained. We selected 10 mucinous cystadenomas (MCAs), 32 intestinal mucinous borderline tumors (IMBTs), and 15 well-differentiated mucinous carcinomas (MCCs), all with goblet cells, at least focally. In all cases, we studied the clinicopathologic features, mucin content, intermediate filament expression, and some nuclear quantitative features, namely, the volume-corrected mitotic index (M/Vi), percentage of nucleolated nuclei, mean number of nucleoli per nucleus, percentage of nucleoli touching the nuclear membrane, and mean nuclear area. The quantitative nuclear study included cytometric DNA analysis and the results were expressed as relative mean ploidy value (RMPV) and as diploid-tetraploid or aneuploid histograms. The results of the quantitative study were evaluated statistically. All patients had stage IA tumors, had received surgical therapy only, and were alive and well after a follow-up of more than 5 years. Light microscopic examination revealed that destructive stromal invasion was not present in any MCCs and that IMBTs and MCCs were easily recognizable using the Hart and Norris criteria, later expanded by Hart. Mucin histochemistry and intermediate filament immunohistochemistry failed to detect substantial differences between the diagnostic categories. DNA analysis demonstrated an increase in aneuploid tumors going from IMBTs to MCCs, but these differences were not statistically significant. On the other hand, nuclear quantitative morphology showed significant differences among the three groups of tumors for all features considered. Forward stepwise discriminant analysis highlighted that MCAs, IMBTs, and MCCs were contiguous but different categories. These data support the separation of IMBTs and MCCs into morphologically different categories as underlined by the results of quantitative nuclear morphologic analysis. The favorable outcome of all patients confirms the excellent prognosis of stage I IMBTs and suggests that well-differentiated MCCs without destructive stromal invasion at stage IA could be assimilated, in terms of prognosis and therapy, into stage I IMBTs.

Organization of nucleoli and nuclear bodies in osmotically stimulated supraoptic neurons of the rat

This study has analyzed variations in the number of nucleoli and nuclear bodies, as well as in their ultrastructural and cytochemical organization, after the osmotically induced activation of supraoptic nucleus (SON) neurons of the rat. The number of nucleoli and nuclear bodies and also the nucleolar size were determined on smear preparations of previously block-impregnated SON. The mean number of nucleoli per cell was 1.35 +/- 0.6 (mean +/- SDM) in control rats. No significant variations in this value were registered either in dehydrated or rehydrated rats. The mean nucleolar volume and the total nucleolar volume per cell showed a significant increase in dehydrated rats with respect to the controls, whereas these two parameters tended to return to control values in rats rehydrated after dehydration. The mean number of nuclear bodies per cell increased significantly from 0.56 +/- 0.50 (mean +/- SDM) in control rats to 1.54 +/- 1.1 after 6 days of dehydration. By electron microscopy, SON neurons displayed a reticulated nucleolar configuration. After the osmotically induced neuronal activation, there was an increase in the proportion of the total nucleolar area occupied by the granular component, and also a reduction in the mean fibrillar-center area. The most characteristic nucleolar features in rehydrated rats were the tendency for the granular component to be segregated and the occurrence of intranucleolar vacuoles. Ultrastructural cytochemistry with a specific silver method revealed a selective silver reaction on the coiled threads of the nuclear bodies--identified as "coiled bodies"--and on the nucleolar fibrillar components in all animal groups studied. Since nucleoli play a major role in ribosome biogenesis, a relationship between these nucleolar changes and the level of cellular activity of SON neurons is proposed. Furthermore, the response of nuclear "coiled bodies" to neuronal activation suggests their participation in the processing and transport of rRNA precursors.

Nucleolar organization in granule cell neurons of the rat cerebellum.

The present light and electron microscopic study deals with the morphology and cytochemical properties of the nucleolus in mature granule cells of the rat cerebellum. Nucleolar organization has been examined by several different methodological approaches: (a) determination of the number of nucleoli per cell from smear preparations, (b) morphometric estimation of nucleolar size, and (c) ultrastructural and cytochemical characterization of nucleolar components. The mean number of nucleoli per cell was found to be 1.46 +/- 0.02 (mean +/- SEM). The morphometric measurement of the nucleolar area showed an average value of 0.359 +/- 0.07 microns 2 (mean +/- SDM). At the electron microscope level, most granule cell nucleoli displayed a fine texture which does not differ substantially from the 'ring-shaped' configuration usually found in cells with low levels of protein synthesis activity; i.e., a large round fibrillar centre surrounded by the dense fibrillar component, and small masses of granular component segregated from the preceding constituents. The meaning of this nucleolar configuration is discussed in the light of recent ultrastructural and biochemical data on nucleolar function. A relationship between this pattern of nucleolar organization and metabolic characteristics of the granule cells is suggested.

Nucleoli numbers and neuronal growth in supraoptic nucleus neurons during postnatal development in the rat

We present a quantitative study of the variations in the number of nucleoli in supraoptic nucleus neurons during the postnatal period, as well as a morphometric and stereological analysis of the nuclear and cytoplasmic volume changes of these maturing neurons. The mean number of nucleoli per cell was 1.59 ± 0.28 (mean ± S.D.) at P1; it then began to decrease until P14 (1.32 ± 0.67) at which age the adult pattern in the number of nucleoli was attained. The mean nuclear volume increased steadily from 214.56 ± 6.48, μm 3 (mean ± S.E.) at P1 to 326.1 ± 10.93 μm 3 at P14 where it remained constant. The average cytoplasmic volume underwent a remarkable increase during postnatal period from 256.38 ± 12.66 μm 3 at P1 to 3791.18 ± 204.88 μm 3 at P90. It is noteworthy that the stabilization of the number of nucleoli coincides with the termination of the nuclear growth phase of supraoptic neurons. We suggest that these nuclear and nucleolar changes reflect the attainment of the fully-differentiated state of the protein synthesis machinery in these neurosecretory neurons.

Some quantitative data regarding the nucleoli in cell nuclei from rat liver of different ploidy classes.

In an investigation comprising different morphometric and numerical data with regard to the nucleoli in smears of isolated parenchymal nuclei of rat liver cells, the following facts were established. 1. Within the three different ploidy classes existing in adult animals, no correlation has been observed between the nucleolar projection area and the number of nucleoli per nucleus. A considerable overlap exists between the numbers of nucleoli in the diploid, tetraploid and octoploid class, so that it is not possible to classify the nuclei of the three classes on the number of nucleoli. 2. The total nucleolar projection area per nucleus in a given ploidy class varies within rather narrow limits, independently of highly variable numbers of individual nucleoli. The means of these nucleolar areas in diploid, tetraploid and octoploid nuclei, showed virtually no deviation from an 1∶2∶4 ratio. 3. The mean numbers of nucleoli in the livers of young adult animals (8 weeks of age) are 2.37, 5.02 and 10.08 for the 2n, 4n and 8n classes, respectively. In embryos and newborn animals, the modal number of nucleoli is 4 in the diploid nucleus, while the first appearing tetraploid and octoploid nuclei, later in development, show at first 8 and 16 nucleoli respectively, the mode of which number falls quickly afterwards. The reduction in nucleolar number, undoubtedly due to fusion, proceeds continuously up to old age: in rats of 21 months, the means are reduced to 1.45 (2n class), 2.66 (4n class) and 5.85 (8n class).

Variation in Nucleolar Number among Varieties of Cultivated Rice

1. The number of nucleoli newly formed in somatic telophasic nuclei was observed in a number of rice varieties from various Asian countries.2. In some varieties, the number of nucleoli varied from two to four from cell to cell, while in other varieties two nucleoli were found in all cells. The former and the latter varieties may correspond to the so-called “quadrinucleolar” and “bi-nucleolar” types.3. About two thirds of the “Continental” varieties and a half of the “Tropical-Insular” varieties were of quadri-nucleolar type. In the former, the mean number of nucleoli ranged from 2.2 to 3.6.4. All Japanese lowland Varieties were of bi-nucleolar type, while both bi- and quadri-nucleolar types were found in different proportions in other regions.5. It was mentioned that rice might have two pairs of nucleolar chromosomes, and the nucleolus-forming power of the second pair being relative to the first, as shown by the mean number of nucleoli, might vary continuously among varieties.

Observations on nuclear size and form in living rat and mouse eggs

Figures are presented for the mean nuclear volume, the mean total nucleolar volume, and the mean number of nucleoli, in the pronuclei of polyspermic rat eggs, in the nuclei of artificially activated 1-cell and 2-cell rat eggs, in the pronuclei and 2-cell nuclei of fertilized mouse eggs, and in the nuclei of artificially activated 1-cell and 2-cell mouse eggs. From a consideration of these data, and of information previously published, the following conclusions have been reached for the eggs of rats and mice: 1. 1. To fulfil the requirements of pronuclear growth, material is drawn from cytoplasmic stores in the egg and is available in just sufficient quantity for the development of pronuclei of normal size and number. Limited availability of material thus constitutes a normal restriction to the growth of the pronuclei. 2. 2. The pronuclei compete for the formative material and the male pronucleus appears to have the greater affinity for it, since it maintains about twice the size of the female pronucleus throughout development. 3. 3. There is, at least in the female pronucleus, also an inherent limit to size; this is not normally operative but becomes so when a female pronucleus develops in the absence of competition from a male. The restriction affects nuclear volume more than total nucleolar volume. 4. 4. Nuclear volume and total nucleolar volume in 2-cell eggs is apparently unrelated to ploidy, since haploid, diploid and triploid eggs have nuclei that differ little from each other. Similarly, the number of nucleoli is evidently no guide to chromosome number. 5. 5. Although mouse and rat eggs have the same vitelline volume (about 200,000 cu.μ), the pronuclei and nuclei are smaller in the mouse egg. It seems likely, however, that the nucleo-cytoplasmic ratio is in reality the same for both species and that the apparent difference in ratio should be imputed to the presence of more yolk in the mouse egg.