Number Of Binuclear Cells Research Articles

The effect of physical activity of varying intensity on cardiomyocyte hypertrophy and myocardial polyploidy in rats

Regular exercise improves cognitive function, reduces the risk of premature death from cardiovascular disease, stroke, diabetes and improves quality of life.Aim: To study the morphological parameters of cardiomyocytes of the left ventricle of the heart and the proliferative activity of rat cardiomyocytes during physical activity of different intensity.Methodology and Research Methods. Outbred male rats (n = 30) were taken as experimental animals and divided into three series. The first series of rats were given light physical activity – the animals swam in the bath for 15 minutes. The animals of the second series were in the bath for 30 minutes (moderate severity), the third series were in the bath until they began to lose strength and sink (in 55–59 minutes). Animals were taken out of the experiment after 10 sessions of water loading. Some rats (5 animals per series) were slaughtered 30 days after the end of the experiment. After extraction, the heart was stained with hematoxylin and eosin, the amount of DNA in the nuclei of cardiomyocytes was determined, binuclear and Ki-67 positive cells were counted, and the diameter of cardiomyocytes was measured. Statistical analysis was carried out in the program “Statistica 10.0”.Results. Histological examination revealed changes only in the myocardium of the left ventricle of rats of the third series: pronounced dystrophic changes in cardiomyocytes. There were cells with necrobiosis, focal necrosis of groups of cardiomyocytes. The highest level of cardiomyocyte polyploidy occurred in the second and third series (the ratio of diploid and tetraploid cardiomyocytes in the control corresponded to 91.6 ± 7.4%; 8.2±6.3%). In these series, there was also a change in the number of binuclear cells (in the control – 12.7 ± 1.9‰). In all series of Ki-67 positive nuclei were not detected.Conclusion. Severe physical activity leads to structural disorders of the myocardium, persistent hypertrophy of cardiomyocytes and is accompanied by a decrease in the proliferative activity of cardiomyocytes.

Biological effects of exposure to copper nanoparticles: markers of exposure

Introduction. Aerosol nanoparticles at operating metallurgical plants are potent of the significant risk factor that needs to be studied.
 The purpose of the work was to study biological effects of exposure to copper nanoparticles compared to microparticles and identify potential markers of the exposure.
 Materials and methods. Two experimental groups of rats, twelve animals each, were subchronically exposed to copper-containing nanoparticles and microparticles injected intraperitoneally. Changes in their biochemical parameters, tissues, and organs were then compared to those in the control rats administered with deionized water. During periodic medical examinations of workers occupationally exposed to copper-containing aerosols with different particle size distribution, additional laboratory and instrumental methods of testing were used to identify possible exposure effects to health manifested by changes in biochemical parameters.
 Results. The experimental study showed that in liver, the exposure to copper nanoparticles, compared to microparticles, induced a more significant inhibition of replication of hepatocytes in regeneration, as demonstrated by the number of binuclear cells, and an increase in the number of Kupffer cells (tissue macrophages), while in kidney, it caused a more pronounced convoluted tubule brush border loss. The exposure to both micro- and nano-sized copper particles was found to induce pathological changes in neurons of the ganglionic layer of the cortex and basal nuclei. Test results showed a significant increase in the blood concentration of ceruloplasmin in the core personnel of the metallurgical plant following the exposure to copper aerosols rich in nanoparticles.
 Limitations. The assessment of the results of the impact of copper nanoparticles in the composition of the aerosol on the health of 224 employees of the enterprise and the results of the experiment obtained on 36 animals corresponded to the current social and ethical standards and norms.
 Conclusion. Specifics of the exposure to nanoparticles require a revision of approaches to regulating aerosols with account for particle size distribution.

Combined clinical and laboratory diagnostics of neurodegenerative disorders

IntroductionAlzheimer’s disease (AD) is a neurodegenerative pathology that develops mainly in elderly and senile people.ObjectivesThe aim of the study was a comparative analysis of the results of neuropsychological tests with the indicators of the study of oral fluid and buccal epithelium cytograms in patients with Alzheimer’s disease.MethodsIn the main group of 12 patients with Alzheimer’s disease, m=76.25±4.89. There were 12 cognitively healthy people in the control group. The average MMSE score among the observations of the main group was 13.42±3.63. The ADAS-COG scale was used to detail the impaired cognitive functions. The concomitant pathology is compensated. The content of BDNF, TNF-α, IL1RA, IL-6, and IL-8 was determined in the oral fluid and in the blood serum. The concentration of salivary and serum biomarkers was determined by multiparametric fluorescence analysis with magnetic microspheres. Micronuclei, karyopycnosis, karyorexis, and karyolysis were determined in the cellular structures of the buccal epithelium. The material for cytological examination was collected from the inner surface of the cheek.ResultsWhen analyzing buccal cytograms, attention was drawn to a pronounced increase in the number of cells with micronuclei in patients with AD to 1.8%; in the control group, the median was 0.1% (p<0.05). A direct correlation was established between the number of binuclear cells and the level of BDNF in the blood serum (r=0.646; p=0.03) in patients with AD. It is also important to note that the level of serum BDNF had a significant direct correlation with immediate memory, and the concentration of salivary BDNF correlates with the parameter of naming objects.ConclusionsCorrelations between amnesia, speech disorders, praxis, gnosis and pathology of the oral fluid and buccal epithelium, especially with the severity of karyopycnosis and karyorexis, have been established, indicating a direct correlation between the neurodegenerative process pathogenetically associated with Alzheimer’s disease and the processes of systemic inflammation and degeneration of the buccal epithelium.Disclosure of InterestNone Declared

AGE FEATURES OF BUCCAL EPITHELIUM IN PRACTICALLY HEALTHY PEOPLE

Recently, buccal epithelium has been used to study age-dependent processes. This approach is of particular relevance due to its non-invasiveness. The purpose of this study is to establish the normal values of the buccal cytogram in different age groups, including athletes. 200 practically healthy volunteers of different ages were examined, who were divided into 5 groups in accordance with the WHO age classification. In addition, 125 professional athletes took part in the study. All patients underwent a comprehensive dental examination and a standard cytological examination of buccal smears. It has been established that the cytological characteristics of buccal epitheliocytes, indirectly reflecting disorders of the nuclear apparatus of the cell, did not change significantly with age, but there was a certain upward trend in the number of cells with such anomalies (micronucleus, protrusions).The number of binuclear cells and the apoptotic index also slightly increase with age. At the same time, a high positive correlation was found between the apoptosis index and senile age. In young athletes, an increase in the number of buccal epitheliocytes with a perinuclear vacuole (an early sign of cell damage) was foundAnalysis of the cytological examination results of the buccal epithelium in people a slight increase in the level of cytological abnormalities in old age, in particular, signs of apoptosis. In addition, in healthy young athletes (18 years old - 44 years old), an increase in the number of cells with signs of nuclear degradation, which most likely reflects increased mechanical stress on the maxillofacial apparatus during sports activities.

Early noninvasive diagnosis of neurodegeneration

AbstractBackgroundAlzheimer's disease (AD) is a neurodegenerative pathology that develops mainly in elderly and senile people. The aim of the study was a comparative analysis of the results of neuropsychological tests with the indicators of the study of oral fluid and buccal epithelium cytograms in patients with Alzheimer's disease.Methodlaboratory, neuropsychologicalResultIn the main group of 12 patients with Alzheimer's disease, m=76.25±4.89. There were 12 cognitively healthy people in the control group. The average MMSE score among the observations of the main group was 13.42±3.63. The ADAS‐COG scale was used to detail the impaired cognitive functions. The concomitant pathology is compensated. The content of BDNF, TNF‐α, IL1RA, IL‐6, and IL‐8 was determined in the oral fluid and in the blood serum. The concentration of salivary and serum biomarkers was determined by multiparametric fluorescence analysis with magnetic microspheres. Micronuclei, karyopycnosis, karyorexis, and karyolysis were determined in the cellular structures of the buccal epithelium. The material for cytological examination was collected from the inner surface of the cheek.When analyzing buccal cytograms, attention was drawn to a pronounced increase in the number of cells with micronuclei in patients with AD to 1.8%; in the control group, the median was 0.1% (p<0.05). A direct correlation was established between the number of binuclear cells and the level of BDNF in the blood serum (r=0.646; p=0.03) in patients with AD. It is also important to note that the level of serum BDNF had a significant direct correlation with immediate memory, and the concentration of salivary BDNF correlates with the parameter of naming objects.ConclusionCorrelations between amnesia, speech disorders, praxis, gnosis and pathology of the oral fluid and buccal epithelium, especially with the severity of karyopycnosis and karyorexis, have been established, indicating a direct correlation between the neurodegenerative process pathogenetically associated with Alzheimer's disease and the processes of systemic inflammation and degeneration of the buccal epithelium.

Use of the results of the study of oral fluid and buccal epithellium in the diagnosis of Alzheimer`s disease

IntroductionThe aim of the study was a comparative analysis of the results of neuropsychological tests with the indicators of the study of oral fluid and buccal epithelium cytograms in patients with Alzheimer’s disease.ObjectivesIn the main group of 12 patients with Alzheimer’s disease, m=76.25±4.89. There were 12 cognitively healthy people in the control group. The average MMSE score among the observations of the main group was 13.42±3.63.MethodsThe ADAS-COG scale was used to detail the impaired cognitive functions. The concomitant pathology is compensated. The content of BDNF, TNF-α, IL1RA, IL-6, and IL-8 was determined in the oral fluid and in the blood serum.Results When analyzing buccal cytograms, attention was drawn to a pronounced increase in the number of cells with micronuclei in patients with AD to 1.8%; in the control group, the median was 0.1% (p<0.05). A direct correlation was established between the number of binuclear cells and the level of BDNF in the blood serum (r=0.646; p=0.03) in patients with AD. It is also important to note that the level of serum BDNF had a significant direct correlation with immediate memory, and the concentration of salivary BDNF correlates with the parameter of naming objects.ConclusionsCorrelations between amnesia, speech disorders, praxis, gnosis and pathology of the oral fluid and buccal epithelium, especially with the severity of karyopycnosis and karyorexis, have been established, indicating a direct correlation between the neurodegenerative process pathogenetically associated with Alzheimer’s disease and the processes of systemic inflammation and degeneration of the buccal epithelium.DisclosureNo significant relationships.

The Effect of Chronic Alcohol Intoxication on the Daily Rhythm of Some Micromorphometric Parameters of Rat Hepatocytes

The effect of chronic alcohol intoxication on the daily rhythm of micromorphometric parameters characterizing the morphological and functional state of the liver is studied on 80 male Wistar rats of 6 months age, divided into 2 equal groups. The first group served as control; rats of the second group (experiment) were kept under similar conditions but got as a drink a 15% ethanol solution ad libitum instead of water. After three weeks of the experiment, animals were euthanized consistently at four-time points during the day. The pathomorphological study of the liver was carried out, the daily dynamics of the nucleus and cell (by area and nuclear-cytoplasmic ratio (NCR)), ploidy of mononuclear hepatocytes, and the proportion of binuclear hepatocytes were measured. The reliability of circadian rhythm (CR) was determined by cosinor analysis. The study indicates complex changes in the organization of rhythmostasis in the experiment. The chrono-destructive effect of experimental alcohol intoxication on the CR of the cell and NCR, as well as the chronomodulating effect to the CR of the nucleus are established. The effect of ethanol on the CR of ploidy and the number of binuclear hepatocytes, as well as on the nature of their variation at the studied time points is established. An increase in the ploidy of hepatocytes and an in the number of binuclear cells is revealed, which indicates the beginning of the deployment of adaptive-compensatory reactions in the organ.

EFFECT OF DOSED NORMOBARIC HYPOXIA ON MORPHO-FUNCTIONAL CHANGES IN HEPATOCYTES OF NORMOTENSIVE AND HYPERTENSIVE RATS

Problem. Study of the effect of dosed hypoxia on the hepatocytes activity and morphometric parameters of rats of different lines.The aim of the work was to investigate and compare the morphological and functional changes in hepatocytes of normotensive and spontaneously hypertensive rats after exposure to dosed normobaric hypoxia.Materials and methods. The study was conducted in the autumn on 48 male rats of the Wistar and SHR line. Experimental animals were given daily hypoxic gas mixture (12 % oxygen in nitrogen) in intermittent mode: 15 minutes deoxygenation / 15 minutes reoxygenation for 2 hours. The duration of the experiment was 28 days. Histological preparations were made from liver tissue using a standard technique. Morphometry was performed using the computer program "Image J". The activity of succinate dehydrogenase and protein concentration in a hepatocytes mitochondrial suspension was determined.Results. It was revealed that morphological changes in the liver parenchyma and biochemical parameters of hepatocyte mitochondria activity in spontaneously hypertensive rats, breathing in a hypoxic gas mixture, were manifested to a greater extent than in animals of the Wistar line. Experimental animals showed an increase in the number of binuclear cells (SHR line) and nucleolus in the nucleus hepatocyte, an increase in nuclear-cytoplasmic and nucleolus-nuclear ratio, as well as an increase in succinate dehydrogenase activity and protein concentration (SHR line) in a suspension of hepatocyte mitochondria. These data may indicate an increase in the functional activity of hepatocytes and activation of physiological cell regeneration at the intracellular level.Conclusions. The effects of dosed normobaric hypoxia have morphofunctional signs of increased physiological regeneration and activity of the liver parenchyma in spontaneously hypertensive rats to a greater extent than in animals of the Wistar line.Key words: liver; intermittent hypoxia; arterial hypertension.

ВЛИЯНИЕ СОЧЕТАННОЙ ТРАНСПЛАНТАЦИИ МУЛЬТИПОТЕНТНЫХ МЕЗЕНХИМАЛЬНЫХ СТРОМАЛЬНЫХ И ГЕМОПОЭТИЧЕСКИХ СТВОЛОВЫХ КЛЕТОК НА РЕГЕНЕРАЦИЮ ПЕЧЕНИ ПОСЛЕ ЕЕ РЕЗЕКЦИИ У СТАРЫХ ЛАБОРАТОРНЫХ ЖИВОТНЫХ

The aim of this study was to study the changes in the morphological and functional state of the liver of old laboratory animals after its resection against the background of combined transplantation of multipotentmesenchymal stromal and hematopoietic stem cells.Materials and methods. The studies were performed on old laboratory animals, male mice of the age of 16-17 months. Resection of 2/3 of the liver was performed in old laboratory mice according to the method of C. Mitchell and H. Willenbring. One hour after subtotal resection, a combined transplantation of two types of cells was performed: multipotentmesenchymal stromal cells (at a dose of 4 million cells / kg) and hematopoietic stem cells (at a dose of 330 thousand cells / kg). The experiments on obtaining the MMSC and HSC culture were performed from the placenta chorion of 10 laboratory female mice 3-4 months old, weighing 20-25 g, gestational age 18 days. Assessment of liver regeneration was carried out on days 1, 3, 7 after resection of the liver by analyzing morphometric parameters of the liver and biochemical parameters of peripheral blood.Results. Studies have shown the activation of protein synthesizing liver function in old animals, a decrease in the level of cytolysis enzymes, an increase in the activity of cellular regeneration (increase in the hepatocyte nucleus area, the number of binuclear cells) of liver regeneration after resection against the introduction of stem cells.

Morphological changes in the rat’s liver of different age after administration of magnesium chloride

The aim of the work was to study the morphological changes in the rat’s liver of different ages after prolonged administration of magnesium chloride. The experiments were performed on 48 Wistar male rats at 3 and 15 months of age. Experi mental animals, in addition to the standard diet, received magnesium chloride daily for 21 days at a dose of 50 mg / kg of body weight. Histological preparations were made from the liver tissue according to the standard method. The liver morphometry was performed on digital images using the computer program Image J. The content of magnesium cations was determined in the serum and suspension of red blood cells. Based on the results of our studies, it can be assumed that the administration of magnesium chloride activates the processes of physiological regeneration and functional activity of the liver parenchyma in rats of different ages. This is evidenced by an increase in the number of binuclear cells and nucleolus in the nucleus of hepatocytes, an increase in the nuclear-cytoplasmic and nucleolar-nuclear ratio. The relative area of the sinusoid network, the number and density of connective tissue cells were increased in the liver of 3-month-old experimental rats. This may indicate an increase of trophic and protective activity of the stroma in this organ. Experimental rats (15-month-old animals) revealed a moderate increasing in the erythrocyte suspension and blood serum magnesium content. The administration of magnesium chloride has the morphological features indicating an increasing of the physiological regeneration and activity of the liver parenchyma in young (to a greater extent) and adult animals.

1151 Impact of dietary protein levels during late pregnancy on the number of binuclear cells in sheep

1151 Impact of dietary protein levels during late pregnancy on the number of binuclear cells in sheep

Increased Cell Fusion in Cerebral Cortex May Contribute to Poststroke Regeneration

In this study, we used a model of a hemorrhagic stroke in a motor zone of the cortex in rats at the age of 3 months The report shows that cortical neurons can fuse with oligodendrocytes. In formed binuclear cells, the nucleus of an oligodendrocyte undergoes neuron specific reprogramming. It can be confirmed by changes in chromatin structure and in size of the second nucleus, by expression of specific neuronal markers and increasing total transcription rate. The nucleus of an oligodendrocyte likely transforms into a second neuronal nucleus. The number of binuclear neurons was validated with quantitative analysis. Fusion of neurons with oligodendrocytes might be a regenerative process in general and specifically following a stroke. The appearance of additional neuronal nuclei increases the functional outcome of the population of neurons. Participation of a certain number of binuclear cells in neuronal function might compensate for a functional deficit that arises from the death of a subset of neurons. After a stroke, the number of binuclear neurons increased in cortex around the lesion zone. In this case, the rate of recovery of stroke-damaged locomotor behavior also increased, which indicates the regenerative role of fusion.

The combined effect of boronophenylalanine and borocaptate in boron neutron capture therapy for SCCVII tumors in mice

Purpose: To increase the effect of boron neutron capture therapy (BNCT) on tumors in vivo, the combined effects of para-boronophenylalanine (BPA) and borocaptate sodium (BSH) were investigated. Methods and Materials: 10B-enriched BPA and BSH were administered to C3H/He mice bearing SCCVII tumors by intragastric and intravenous injections, respectively. The colony formation and tumor control assays were employed for investigating antitumor effects of BNCT. The extent of homogeneity of tumor cell killing effect was examined by the distribution of frequencies of binuclear cells (BNC) producing a certain number of micronuclei (0,1,2,—-,≥5) to total number of BNC and by the comparison between surviving cell fraction (SF) in colony formation assay and the normal nuclear division fraction (NNDF) at first mitosis following BNCT. Results: The relationships between SF and radiation dose in Gy (D) at around 10 ppm of 10B in tumors were as follow: −lnSF = −0.101 + 0.648 Gy -1 × D, 0.0606 + 0.435 Gy -1 × D, and −0.0155 + 0.342 Gy -1 × D for BPA, BPA + BSH, and BSH, respectively. In tumor control assay, BPA was also more effective than BSH, but the difference of effectiveness significantly decreased: 1.9 times more effective in colony assay vs. 1.2 times in tumor control assay. The most effective treatment to achieve tumor cure was BNCT using BPA + BSH, and it was 1.9 times more effective than BSH-BNCT. In BSH-BNCT, NNDF decreased exponentially with radiation dose and was equal to SF. However, NNDF following BPA-BNCT showed a biphasic decrease with radiation dose, and SF was much lower than NNDF. In the combination of BPA and BSH, the discrepancy between NNDF and SF decreased in comparison with BPA-BNCT. The distribution of frequency of BNC with a certain number of micronuclei to total BNC was very close to Poisson distribution in BSH-BNCT tumors; however, it deviated from the Poisson in BPA-BNCT tumors. In combination with BPA and BSH, the distribution showed an intermediate pattern. These findings indicate that BSH distributes homogeneously with a heterogeneous distribution of BPA in tumors, and the heterogeneous effect of BPA-BNCT was improved by the combination of two boron compounds. Conclusion: The heterogeneous cell killing effect of BPA-BNCT was improved by the combination of BSH, and increased tumor control rates. Therefore, this combination may improve clinical outcome of BNCT although the effects on normal tissues have to be examined before clinical application.

The effect of lecithin supplementation on the biochemical profile and morphological changes in the liver of rats fed different animal fats.

Sixty-four Wistar rats were divided into 8 equal groups and kept for 36 days in individual boxes. Three of the groups were given full synthetic diets containing various animal fats: beef tallow, pork fat or fish oil. A control group was fed the diets without the fat. The other four groups were fed the same diets with lecithin supplementation. At the end of experiment, sections taken from the liver were stained with haematoxylin eosin and Sudan III to indicate fat infiltration. Liver enzyme levels, total bilirubin, albumin and two products of lipid metabolism were measured in serum from all the animals. The addition of lecithin to the diets did not influence the level of enzymes in the serum except in rats fed the diet containing beef tallow. A relationship between the type of diet, lecithin supplementation and the total cholesterol concentration in serum was observed. The concentration of HDL-cholesterol was only influenced by lecithin supplementation and that of triglycerides by the type of fat in the diet. The addition of lecithin to the diet was associated with proliferation of Kupffer cells, and an increased number of binuclear cells. Fatty degeneration of hepatocytes was less pronounced in all groups following lecithin supplementation. Lecithin supplementation of the diet did not elicit any pathological lesions and may be considered as a hepatocyte protector. This favourable effect of lecithin was most marked in the group of rats fed the fish oil.

840 A radioresistant line of rat Guerin’s carcinoma: Its obtention, properties and a regimen of radiothermotherapy

We obtained a radioresistant line of rat Guerin's carcinoma through repeated courses radiotherapy (5 sessions of 10 Gy each). We followed 14 subsequent passages of the line, revealed a complex of signs testifying to radioresistance of tumor cells: an increase in their morphologic heterogeneity, nuclear and cellular area, number and size of nucleolus and number of binuclear cells. We proved alterations in the subpopulation composition of Guerin's carcinoma cells with an increase in the proportion ofslowly proliferating but more radioresistant cells. A radioresistant line also features increased antioxidative activity of tumor cells, levels of non-protein thyol groups, induction of stress proteins with 140—150 kDa, whose levels are the same between the courses of radiotherapy, as well. It is experimentally shown that hyperthermia before radiotherapy effective. We obtained a radioresistant line of rat Guerin's carcinoma through repeated courses radiotherapy (5 sessions of 10 Gy each). We followed 14 subsequent passages of the line, revealed a complex of signs testifying to radioresistance of tumor cells: an increase in their morphologic heterogeneity, nuclear and cellular area, number and size of nucleolus and number of binuclear cells. We proved alterations in the subpopulation composition of Guerin's carcinoma cells with an increase in the proportion ofslowly proliferating but more radioresistant cells. A radioresistant line also features increased antioxidative activity of tumor cells, levels of non-protein thyol groups, induction of stress proteins with 140—150 kDa, whose levels are the same between the courses of radiotherapy, as well. It is experimentally shown that hyperthermia before radiotherapy effective.

Morphometric study of alterations of extrafocal hepatocytes of rat liver treated with N-Nitrosomorpholine

Male Sprague-Dawley rats were treated with the hepatocarcinogen N-nitrosomorpholine for 7 weeks and observed for up to 40 weeks after withdrawal of the carcinogen. In addition to the focal preneoplastic lesions described earlier there were also alterations in extrafocal hepatocytes and these changes have been quantified morphometrically. Since the periportal and perivenous hepatocytes were not altered to the same extent, cells of the periportal zone (PPZ) and cells of the perivenous zone (PVZ) were measured separately. Immediately after stopping treatment there was marked enlargement of the hepatocellular cytoplasm and of the nuclei in both the PPZ and the PVZ and a reduction in the number of binuclear hepatocytes. While these alterations were totally reversed during the first 10 weeks after treatment ceased in the PPZ, statistically significant changes in nuclear size, nuclear-cytoplasmic ratio and number of binuclear cells persisted in the PVZ up to 40 weeks after the end of treatment. We suggest that both the foci of altered hepatocytes as well as the persisting changes in extrafocal hepatocytes may be involved in the process of hepatocarcinogenesis.

Morphometric analysis of changes in hepatocytes of rabbits with experimental hypercholesterolemia and their reversibility

Two-week cholesterol injections caused prolonged alterations of nuclear hepatocyte apparatus in all liver segments. These alterations resulted in the increased number of binuclear cells and hepatocytes containing large nuclei detected 1.5 month after the last cholesterol injection.

Effect of absence of polyploid hepatocytes on regeneration in the liver

An autoradiographic study with [3H]thymidine showed that the hepatocytes of young sexually mature guinea pigs commence the phase of DNA synthesis 25 h after partial hepatectomy. Peaks of the number of labeled nuclei were found 30, 45, and 60 h after the operation. Two waves of mitoses were found by counting mitotic figures in squash preparations: 40 and 55 h after hepatectomy. A cytophotometric study of the DNA content showed that practically all the mononuclear and binuclear hepatocytes contained diploid nuclei 3 and 5 days after the operation. By the end of the 7th day of regeneration there were 6% of mononuclear tetraploid cells. The number of binuclear cells fell during the period of regeneration studied from 16 to 8%. It is concluded that the principal cytological mechanism of liver regeneration in guinea pigs is normal mitosis terminating in separation of the cells.

Cytological analysis of the intact and regenerating liver of various strains of rats

A comparative cytological study was made of the control and regenerating liver in two strains of rats: August and cotton-tail. Two-thirds of the liver was removed from both groups of experimental animals and the intact organ served as the control. The animals were killed five or six at a time 30 h and 3, 8, 42, and 120 days after partial hepatectomy. The number of binuclear cells, the dimensions of the mononuclear hepatocytes and of their nuclei, and the mitotic activity and ploidy of the cells were studied. With the exception of mitotic activity, the regenerating and intact liver of the August rats differed from the regenerating and intact liver of the cotton-tail rats in all the above-mentioned cytological parameters. It is concluded that differences in the cytological parameters between the two different strains are due to the genotype of the particular strain.

Cytological features distinguishing growth of the rat liver in the embryonic and neonatal periods and during regeneration

Embryonic and neonatal growth of the liver was studied in August rats and compared with growth of the regenerating liver of adult animals in the early stages after partial hepatectomy (22, 48, and 72 h after removal of two thirds of the organ). The mitotic activity and area of the nuclei of the hepatocytes were determined and the number of binuclear cells counted. Several general principles were discovered in the dynamics of the changes in the cytological parameters of embryonic and neonatal growth of the intact liver and growth of the regenerating liver of adult rats in the early stages after resection.