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Results for “Laser Scanning Cytometry”

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At least 325 records · Page 18Linked to original sources

PubMed2002

[Upregulation of vascular endothelial growth factor by peroxide in human colon cancer].

OBJECTIVE: To clarify the possible effect of reactive oxygen species such as hydrogen peroxide on progression of human colorectal cancer. METHOD: Human colon carcinoma cell lines, L174T and HCT8, were treated with low concentration of hydrogen peroxide (10(-5) mol/L, 10(-7) mol/L and 10(-9) mol/L, possessed no effect on cancer cell growth) for 24 hours before being co-cultured with human endothelial cell line ECV-304. The migration of ECV-304 induced by cancer cells was calculated and the expression of vascular endothelial growth factor (VEGF) in cancer cells was determined using RT-PCR and ELISA. Dactinomycin (1.5 microg/ml) was applied to block the transcription of cancer cell so as to observe the effect site of cell. Finally the activity of NF-KappaB of cancer cells was estimated using laser scanning cytometry. RESULTS: Exogenous hydrogen peroxide of low concentration promoted the migration of endothelial cell induced by colon cancer cell. When the concentration of H(2)O(2) was 10(-5) mol/L, the average number of migration of endothelial cell induced by LS174T was 202.6 +/- 70.2, higher than the value of 154.6 +/- 37.9 when no H(2)O(2) was given (t = 3.4751, P = 0.0083). When the concentration of H(2)O(2) was 10(-5) mol/L, the average number of migration of endothelial cell induced by HCT8 was 145.4 +/- 65.3, higher than the value of 113 +/- 72.7 when no H(2)O(2) was given (t = 4.4183, P = 0.0084). The expression of vascular endothelial growth factor in cancer cells was enhanced to a certain degree, which could be blocked by Dactinomycin. And the half-time of VEGF mRNA was not prolonged by treatment with hydrogen peroxide. The activity of NF-KappaB of both colon carcinoma cell lines was at a higher level after being treated with hydrogen peroxide for 24 hours. CONCLUSION: Hydrogen peroxide increases vascular endothelial growth factor expression in colon cancer cell, and it is possible that such reactive oxygen species as hydrogen peroxide facilitates development of colon cancer.

Colonic Neoplasms↗

PubMed2002

Effect of As2O3 on cell cycle progression and cyclins D1 and B1 expression in two glioblastoma cell lines differing in p53 status.

Recent clinical studies have demonstrated that As2O3 is an effective drug in the treatment of acute promyelocytic leukemia (APL) by inducing apoptosis and inhibiting the proliferation of leukemia cells both in vitro and in vivo. As a novel anticancer agent for the treatment of solid cancer, As2O3 is promising, but no experimental investigations of its efficacy on glioblastoma have been conducted at concentrations that may be achieved clinically. In addition, the cell proliferation and cell cycle regulating mechanism of As2O3 has not yet to be clarified, especially in solid cancers. We investigated the effect of As2O3 on proliferation and cell cycle regulation with change in cyclins in two human glioblastoma cell lines differing in p53 status (U87MG-wt; T98G-mutated). Sensitivity to As2O3 varied depending on the dose with the IC50 of the U87MG and T98G cells being 1.78 and 3.55 microM, respectively. Analysis by laser scanning cytometry (LSC) indicated that As2O3 inhibited the proliferation of the two cell lines via cell cycle arrest both at the G1 and G2 phases. To address the mechanism of the antiproliferative effect of As2O3, we examined its effect on cell cycle-related proteins by means of LSC, confocal microscopy and Western blot analysis. As2O3 induced an increase in p53 level and a decrease in level of cyclin B1 combined with cell arrest at G2/M in both cell lines. Cell arrest in G1, however, was associated with a decline in cyclin D1 expression only in the wt U87MG cells. As2O3 also induced apoptosis of U87MG cells as evidenced by the presence of cells with fractional DNA content ( cell populations). The present evidence that As2O3 at relatively low concentration effectively inhibited proliferation of U87MG and T98G cells in vitro, suggests that the drug may be considered for in vivo testing on animal models and possibly clinical trials on glioma patients.

Arsenic Trioxide↗

PubMed2002

Immunohistological analysis of immune cell infiltration of a human colon tumor xenograft after treatment with Stealth liposome-encapsulated tumor necrosis factor-alpha and radiation.

The toxicity associated with tumor necrosis factor-alpha (TNF-alpha) has limited its usefulness as an anticancer agent. However, encapsulation of TNF-alpha in Stealth (SL) liposomes can minimize risk for toxicity and thus increase its potential as an adjuvant treatment. Our recent studies have shown that SL-TNF-alpha plus radiation is more effective at inhibiting LS174T colon tumor growth than either radiation alone or free TNF-alpha plus radiation. This increase in efficacy was coincident with a modulation of immune parameters in blood and spleen. The aim of this study was to determine if infiltration of natural killer (NK) cells, macrophages, and neutrophils into LS174T tumors was altered by SL-TNF-alpha treatment and whether any observed changes could potentially contribute to the enhanced antitumor efficacy seen with SL-TNF-alpha plus radiation treatment. Sections of excised tumors were examined histologically and quantitative analysis was performed using laser scanning cytometry. The data showed that the group receiving multiple treatments with SL-TNF-alpha plus radiation had the smallest tumors, but yet the level of necrosis was similar to that found in groups with much larger tumors. Furthermore, the necrotic areas in the SL-TNF-alpha plus radiation group had signs of recent and/or continuing cell death and the highest levels of NK cell and macrophage infiltrates. In time course experiments, a single injection of SL-TNF-alpha (but not free TNF-alpha) induced fluctuations in leukocyte infiltration into tumors that correlated inversely with our previous findings in blood and spleen. Overall, the data indicate that the mechanisms underlying the increased efficacy of SL-TNF-alpha compared to free TNF-alpha include a rapid and relatively sustained recruitment of NK cells, macrophages, and neutrophils.

Animals↗

PubMed2003

[Influence of combined cyclosporine A and tacrolimus with 5-fluorouracil on hepatocellular carcinoma rats].

OBJECTIVE: To investigate the effect of combined CsA and FK506 with 5-FU on hepatocellular carcinoma rats. METHODS: A syngeneic rat model of hepatocellular carcinoma was used. Control group (A) underwent 4 ml 5% GS. Treatment group was divided into 3 groups namely, group B: only 5-FU and 5% GS; group C: 5-FU, CsA and 5% GS; group D: 5-FU, FK506 and 5%GS. Cell cycle, apoptosis, necrosis and mitochondrial transmembrane potential were measured by flow cytometry, laser scanning confocal microscopy, and electron transmission microscopy. Statistical analysis was performed by SPSS 10.0 for Windows software. Statistical comparisons were made with ANOVA followed by Dunnett's T3 or LSD test. RESULTS: Compared to the control group, the percentage of apoptotic cells including trifle necrotic cells was significantly higher, and among the treatment group, group D was the highest, and group C was higher than group B. In the treatment group, cell cycle of hepatoma cells was mainly arrested at S phase, but in group D, G0/G1 phase cells were significantly decreased and S phase cells significantly increased. Compared to the control group, mitochondrial transmembrane potential was significantly decreased in the treatment group, among with, group B was the lowest, group C was higher than group D. Morphological changes demonstrated by electron microscopy included dispersed nuclear chromatin, loss of nucleoli, membrane bleeding, cell shrinkage, typical apoptotic bodies and marked swelling of mitochondria in the treatment group. In the control group, however, they were characterized by normal cell ultrastructure. CONCLUSIONS: The present study reveals that 5-FU combined with CsA or FK506 demonstrated a synergistic effect on hepatocellular carcinoma rats. For FK506, the powerful mutual effect is related to the increase of tumor cell's quantity in S phase. Both CsA and FK506 can provide protection on mitochondrial transmembrane potential reduction against hepatoma cells damage from 5-FU.

Animals↗

PubMed2003

11q23-24 loss is associated with chromosomal instability in endometrial cancer.

A loss of the DNA copy number at chromosomal region 11q23-24 as detected by comparative genomic hybridization (CGH) is a marker of poor prognosis in patients with endometrial cancer. Malignant tumors display genetic instability, which is classified into two types: microsatellite instability (MIN) and chromosomal instability (CIN). In the present study, we examined whether there is a relation between loss of 11q23-24 and genetic instability in endometrial adenocarcinoma. Loss of 11q23-24 was detected in 4 of 70 endometrial cancers by fluorescence in situ hybridization (FISH), and DNA aneuploidy was detected by laser scanning cytometry (LSC) in 14 tumors. All tumors with 11q23-24 loss were aneuploid, and three of them were considered to have CIN. These findings suggest that 11q23-24 contains gene(s) necessary for normal chromosome replication and cell division.

Adult↗

PubMed2004

Induction of H2AX phosphorylation in pulmonary cells by tobacco smoke: a new assay for carcinogens.

DNA double strand breaks (DSBs) are potentially carcinogenic lesions. The induction of DSBs triggers phosphorylation of histone H2AX. Phosphorylated H2AX, denoted p-H2AX, may be detected immunocytochemically and the intensity of p-H2AX immunofluorescence (IF) reveals the frequency of DSBs. Using this assay we tested whether the exposure of A549 human pulmonary adenocarcinoma cells to tobacco smoke, and normal human bronchial epithelial cells (NHBE) to tobacco smoke condensate, induces DSBs. Cellular p-H2AX IF and DAPI fluorescence of individual cells were measured by laser scanning cytometry (LSC). Exposure of A549 cells to tobacco smoke and NHBE cells to smoke condensate led to H2AX phosphorylation in both a time and dose dependent manner. The maximal rate of H2AX phosphorylation was seen during the initial 4h of cell treatment. At high doses (50 microg/ml of smoke condensate), H2AX phosphorylation continued to increase for up to 24h. No differences in the level of H2AX phosphorylation were apparent between cells in G(1) vs S vs G(2)/M phase of the cell cycle in response to treatment with smoke condensate. The data provide strong evidence that exposure of A549 cells to tobacco smoke or NHBE cells to smoke condensate rapidly induces DSBs in these cells. The present assay to detect and measure DSBs induced by tobacco products complements other mutagenicity assays and may be applied to test potential carcinogens in other products.

Adenocarcinoma↗

PubMed2005

Genomic alterations detected by comparative genomic hybridization in primary lung adenocarcinomas with special reference to the relationship with DNA ploidy.

To clarify the clinicopathological and biological significance of genomic alterations in pulmonary adenocarcinomas, we examined chromosomal DNA sequence copy number aberrations (DSCNAs) and DNA ploidy in 42 surgically resected specimens by comparative genomic hybridization (CGH) and laser scanning cytometry (LSC), respectively. The number of DSCNA did not affect the size of carcinoma or number of nodal metastasis. More than 60% of carcinomas showed a 1q21-23 gain or 13q21 loss. Gains of 9q22-33 and 10q26-qter and a loss of 15q14-qter were significantly associated with nodal metastasis (p<0.05). Of 42 pulmonary adenocarcinomas, 32 (76%) showed DNA aneuploidy. The number of DSCNAs in aneuploid carcinomas was larger than that in diploid carcinomas (p<0.01). Our results suggest that diploid and aneuploid types are cytogenetically different in pulmonary adenocarcinomas and aneuploid carcinomas are genetically more unstable and aggressive than diploid carcinomas.

Adenocarcinoma↗

PubMed2006

Activated Leukocyte Cell Adhesion Molecule (ALCAM) is associated with suppression of breast cancer cells invasion.

BACKGROUND: Activated Leukocyte Cell Adhesion Molecule (ALCAM) is expressed in different kinds of normal and neoplastic tissues. Data on the tissue distribution of ALCAM suggest that this protein is involved in tumor progression and metastasis. The lack of available data on ALCAM protein expression in breast cancer prompted us to undertake a study on the involvement of this adhesion molecule in tumor development. MATERIAL/METHODS: The expressions of ALCAM and reference biomarkers were examined in 56 breast cancer specimens by laser scanning cytometry and confocal microscopy. The results were related to clinical and pathological parameters, i.e. histological grade, tumor diameter, lymph node involvement, NPI, steroid receptor (estrogen, ER, and progesterone, PgR) expression, and HER2/neu over-expression. RESULTS: High levels of ALCAM significantly correlated with small tumor diameter (p=0.009), low tumor grade (p=0.001), and the presence of progesterone (p=0.009) and estrogen (p=0.006) receptors. Declining ALCAM concentrations correlated with HER2/neu gene amplification, inasmuch as the obtained p value, 0.065, was very close to the established statistical significance level of p=0.05. The ALCAM/MMP-2 ratio was significantly higher in cancer cases characterized by small tumor size (p=0.04) and low tumor grade (p=0.022). CONCLUSIONS: Analysis of ALCAM expression in relation to other molecular biomarkers revealed that ALCAM expression and the ALCAM/MMP-2 ratio are more promising indicators of breast cancer progression than MMP-2, E-cadherin, and alpha-catenin. Low ALCAM concentration correlated with an aggressive tumor phenotype, which supports the view that this adhesion molecule is a tumor suppressor marker with prognostic significance.

Antigens, CD↗

PubMed2006

ALCAM/CD166 protects breast cancer cells against apoptosis and autophagy.

BACKGROUND: Activated leukocyte cell adhesion molecule (ALCAM/CD166) is a 105-kDa transmembrane glycoprotein linked with cell migration and development and with cancer progression (malignant melanoma, prostate cancer and, very recently, breast cancer). This report is the first evaluation of ALCAM/CD166 in an estrogen-dependent (MCF-7) and a metastatic (MDA-MB-231) breast cancer cell line and a reference breast cell line (HBL-100). The effects of estrogen and anti-estrogen treatment, bcl-2 overexpression, and ALCAM gene silencing on ALCAM/CD166 protein concentration and cell survival were investigated. MATERIAL/METHODS: Laser scanning cytometry, confocal microscopy, and Western blotting were used for the determination of ALCAM/CD166 protein and biochemical markers of apoptosis and autophagy. RESULTS: 17-beta-estradiol increased and tamoxifen inhibited ALCAM/CD166 expression and survival of MCF-7 cells. Overexpression of the bcl2 gene in MCF-7 bcl2/neo, MDA-MB-231 bcl2/neo, and HBL-100 bcl2/neo cells significantly increased ALCAM/CD166 expression and was accompanied by decreasing MMP-2 concentrations. Appearance of the ALCAM/CD166 protein was noted in HBL-100 bcl2/neo in contrast to an almost undetectable level in HBL-100 cells. ALCAM gene silencing in MCF-7 cells decreased the concentration of BCL-2 and increased levels of apoptosis (89-kDa PARP, active caspase7) and autophagy (MAP1LC3, Beclin1) markers. CONCLUSIONS: The above results indicate that ALCAM-ALCAM interactions are crucial to the survival and primary site maintenance of breast cancer cells. Impaired expression of ALCAM/CD166 is associated with the induction of two types of programmed cell death, apoptosis and autophagy, in breast cancer cells. This adhesion molecule can therefore be regarded as a potential novel breast cancer indicator and therapeutic target.

Activated-Leukocyte Cell Adhesion Molecule↗

PubMed2006

Application of laser-scanning fluorescence microplate cytometry in high content screening.

The resolution of cell-based assays down to the cellular level has created new opportunities for the drug discovery process. Aptly named high content analysis, such an approach is enabling new methods of analysis for the broad range of therapeutic targets emerging in the post-genomics era, and offering alternative multiparametric readouts for some traditional analyses. Microplate cytometry is one of the technologies that is being applied to a broad range of assays utilizing fluorescent labeling, at throughputs compatible with primary screening campaigns. Cellular resolution is achieved using scanning laser excitation coupled to photomultiplier detection. This configuration results in area-based scanning across a large field of view, plus simultaneous detection of up to four emission colors for efficient multiplexing. Microplate cytometry is being used most extensively in the field of oncology research because of its usefulness for numerous applications, including protein kinase activity, cell cycle analysis, and cell colony formation. The review focuses on the Acumen Explorer microplate cytometer (TTP LabTech Ltd., Melbourn, Hertfordshire, UK), detailing the principal components of the instrument and providing an overview of its use in high content screening.

Animals↗

PubMed1993

Detection of human papillomavirus DNA in CaSki and HeLa cells by fluorescent in situ hybridization. Analysis by flow cytometry and confocal laser scanning microscopy.

CaSki and HeLa cell lines, isolated from human uterine carcinomas and containing integrated human papillomavirus (HPV) DNA type 16 and 18, respectively were used to evaluate the sensitivity of HPV-DNA detection on suspended cells by fluorescent in situ hybridization using flow cytometry and on corresponding cell deposits using confocal laser scanning microscopy (CLSM). HPV DNAs were detected in cell suspensions with biotinylated DNA probes and revealed with a three-step technique: a rabbit antibiotin antibody, a biotinylated goat anti-rabbit antibody and a streptavidin-fluorescein isothiocyanate complex. By flow cytometry, HPV DNA was detectable only in CaSki cells which contained about 600 copies of HPV DNA per cell. In HeLa cells, with only 20-50 copies of HPV DNA, flow cytometry could not detect HPV DNA, whereas CLSM permitted visualization of fluorescent labelling of HPV DNA hybrids. Furthermore, CLSM showed good preservation of cellular morphology and the nucleus was clearly recognizable after fluorescent in situ hybridization and counterstaining with propidium iodide. Moreover, this examination confirmed that the fluorescent foci were specifically confined to the cell nuclei.

DNA, Viral↗

PubMed1999

[Laser spatial scanning in flow cytometry].

The main flow laser cytometry principles, based on the elastic light scattering, spheres of its applications, problems of its realization and utilization in the immunological investigations and diagnostics are analysed. The experimental model of a flow cytometer with laser probing beam space scanning, originally proposed by the authors, is described. The apparatus was tested by polystyrene latex spheres and biological objects. The experiments showed that the achieved sensitivity was enough to register red blood cells, their complexes and bacterial cells.

Flow Cytometry↗

PubMed1997

Three-dimensional DNA image cytometry by confocal scanning laser microscopy in thick tissue blocks of prostatic lesions.

DNA ploidy provides important information for the evaluation of the prognosis of prostate cancer. For the purpose of DNA cytometry and nuclear measurements, we developed an image processing system for the acquisition and processing of three-dimensional (3D) images based on confocal scanning laser microscopy (CSLM). The advantage of the CSLM is the preservation of the tissue architecture and the possibility of multilabeling. It is possible to determine both individual nuclear features and cellular features and the degree of the spatial heterogeneity of several markers. Special attention was paid to the development of the automatic method for the 3D segmentation of cell nuclei. Thick tissue slides (100 microm), stained for DNA with chromomycin A3, from 4 patients (with benign hyperplasia, prostatic intraepithelial neoplasia (PIN), and well-and poorly-differentiated adenocarcinoma of the prostate), were studied in order to test the practicability of the developed methodology. DNA histograms showed a single peak in the diploid range for the hyperplasia and PIN cases. For the case of well-differentiated carcinoma, 2 peaks were observed, 1 in the diploid range and I in the tetraploid range. The case of poorly-differentiated carcinoma was characterized by an aneuploid distribution. For the cases of PIN and carcinomas, we observed a considerable variation of the volume of nuclei.

Adenocarcinoma↗

PubMed2001

Encystation of Acanthamoeba castellanii: dye uptake for assessment by flow cytometry and confocal laser scanning microscopy.

AIMS: To develop rapid means of distinguishing between cysts and trophozoites of the opportunistic pathogen, Acanthamoeba castellanii, the causative agent of keratitis. METHODS AND RESULTS: Fluorescence of Congo Red, Calcoflor White was specific for the endocyst wall; trophozoites did not become fluorescent. The anionic oxonol dye, DiBAC4(3), did not penetrate the cytoplasmic membrane after short-term (<5 min) exposure, whereas cysts are permeable and become fluorescent. Confocal scanning laser microscopy confirmed these properties and large populations of organisms were analysed by flow cytometry. CONCLUSION: These data provide a rapid alternative to traditional haemocytometer or plate counts for discrimination of trophozoites from cysts. SIGNIFICANCE AND IMPACT OF THE STUDY: Rapid and precise determination of the growth cycle of a dangerous ocular pathogen.

Acanthamoeba↗

PubMed1996

Three-dimensional confocal laser scanning DNA ploidy cytometry in thick histological sections.

DNA ploidy measurement by flow (FCM) or image cytometry (ICM) of single cell suspensions of solid tumour has prognostic value, but it would be a definite advantage if the assessment could be done on histological sections. However, this is usually not possible by means of standard ICM, due to the capping of nuclei in thin sections, or overlap in thick sections. Three-dimensional (3D) microscopy by means of confocal laser scanning microscopy (CLSM) could solve this problem in theory but the results published so far are not very satisfactory. A new method has been developed in which the DNA content of haploid (human testis spermatozoa), diploid, tetraploid, octaploid (human and rat liver and human spermatogonia), and near-triploid (human breast cancer) nuclei stained with YOYO-1 iodide has been measured by a newly developed 3D image cytometry method (3DICM) in 20 microns thick histological sections. YOYO-1 iodide is a new highly sensitive, specific, stoichiometric, and stable fluorescent dye for DNA. DNA ploidy of a breast cancer which was near-triploid with FCM and ICM was also assessed with 3DICM in a tissue section adjacent to the section used for FCM and ICM and the results were compared. The integrated 3DICM fluorescence intensity showed good linearity (r = 0.99) with the real DNA content of all nuclei analysed. In human tissue, the coefficient of variation of 3DICM for haploid (n = 12), diploid (n = 63), triploid (n = 13), tetraploid (n = 12), and octaploid (n = 3) ploidy distributions was 5.1, 6.6, 4.2, 4.0, and 0.6 per cent, respectively (n = the number of nuclei). For the rat liver, the CV of the diploid (n = 21), tetraploid (n = 31), and octaploid (n = 3) peaks was 6.7, 4.8, and 1.6 per cent, respectively. Repeated "blind' measurements of nuclei with different DNA indices showed excellent reproducibility between different observers (r = 0.98). It is concluded that the 3DICM method used is accurate, reproducible, and clinically feasible in thick histological sections. This is especially important in small lesions, or if the results of DNA ploidy measurement of single cell suspensions (by FCM) or imprints (by ICM) are inadequate.

Animals↗

PubMed2006

Scanning cytometry with a LEAP: laser-enabled analysis and processing of live cells in situ.

BACKGROUND: Scanning cytometry now has many of the features (and power) of multiparameter flow cytometry while keeping its own advantages as an imaging technology. Modern instruments combine capabilities of scanning cytometry with the ability to manipulate cells. A new technology, called LEAP (laser-enabled analysis and processing), offers a unique combination of capabilities in cell purification and selective macromolecule delivery (optoinjection). METHODS: LEAP-mediated cell purification and optoinjection effects were assessed in model experiments using adherent and suspension cell types and cell mixtures plated and processed at different densities. Optoinjection effects were visualized by delivering fluorescent dextrans into cells. Results were analyzed using the LEAP instrument's own imaging system as well as by fluorescence and confocal microscopy. RESULTS: Live cell samples (adherent and suspension) could be purified to 90-100% purity with 50-90% yield, causing minimal cell damage depending on the cell type and plating density. Nearly one hundred percent of the targeted cells of all cell types examined could be successfully optoinjected with dextrans of 3-70 kDa, causing no visual damage to the cells. Indirect optoinjection effects were observed on untargeted cells within 5-60 microm to targeted areas under conditions used here. CONCLUSIONS: LEAP provides solutions in cell purification and targeted macromolecule delivery for traditional and challenging applications where other methods fall short.

Animals↗

PubMed1992

[Confocal laser scanning microscopy for image cytometry].

By using a focused laser beam as the light source of the microscope, to minimized flare, together with a pinhole in front of a photo detector to eliminate out-of-focus data, the confocal laser scanning microscope (CLSM) provides a depth-discriminated fluorescence image with high spatial resolution. The CLSM, therefore, has been widely used as a tool for accurate morphometric and densitometric analyses. We discussed here the biological applications of CLSM for demonstrating the three-dimensional features of the embryonic heart tube and chromosome and for imaging fast dynamic changes of [Ca2+]i in the living heart muscle cell pairs.

Animals↗

PubMed1991

Three-dimensional DNA image cytometry by confocal scanning laser microscopy in thick tissue blocks.

A method for the quantification of nuclear DNA in thick tissue blocks by confocal scanning laser microscopy is presented. Tissues were stained en bloc for DNA by chromomycin A3. Three-dimensional images, 60 microns deep, were obtained by stacking up confocal fluorescent images obtained with an MRC-500 (Bio-Rad, Richmond, CA). The effects due to bleaching and attenuation by depth of fluorescence emission were corrected mathematically. The DNA contents were estimated by summing up the detected emission intensities (discretized into pixel gray levels) from each segmented nucleus. Applications to an adult rat liver and to a human in situ carcinoma of theesophagus are shown to demonstrate, respectively, the precision of the method and its potential usefulness in histopathology. Comparisons are made with DNA histograms obtained on the same materials by image cytometry on smears and by flow cytometry. Ploidy peaks obtained with the confocal method, although wider than with other methods, are well separated. Confocal image cytometry offers the invaluable advantage of preserving the tissue architecture and therefore allowing, for instance, the selection of histological regions and the evaluation of the degree of heterogeneity of a tumor.

Animals↗