Die Verteilung der Chromosomen auf die Tochterzellkerne multipolarer Mitosen in euploiden Gewebekulturen von Microtus agrestis

In kidney epithelial cultures from female Microtus agrestis, 3,55% of all mitoses are multipolar, 94% of them tripolar. Feulgen photometric measurements of 21 tripolar mitoses reveal a total DNA amount corresponding to the mitotic diploid value (4c) in 5 cases, and to the tetraploid value (8c) in 16 cases, Diploid tripolar mitoses divide into one daughter nucleus with a diploid DNA value (2c) and two nuclei each with a haploid DNA value (1c). Most tetraploid tripolar mitoses divide into one daughter nucleus with a diploid DNA value (2c) and two nuclei with a triploid DNA value (3c). Also the sex chromosomes are distributed to the daughter nuclei in the relation of 2∶3∶3. This can be seen in anaphase figures as well as in interphase nuclei presumably derived from tripolar mitoses, showing chromocenters according to the number of X-chromosomes. In two cases of tripolar tetraploid mitoses the resulting nuclei have a haploid, a triploid and a tetraploid DNA value. The DNA replication pattern is always identical in the daughter nuclei of diploid and tetraploid tripolar mitoses. — Our observations suggest segregation and distribution of haploid chromosome sets or multiples of haploid sets to the daughter nuclei of multipolar mitoses. They also show a possible way of formation of haploid and triploid cells in a basically diploid tissue. Presumably triploid nuclei (with 3 chromocenters) are capable of DNA synthesis.     

DNA ploidy and S-phase fraction in carcinoma of the gallbladder related to histopathology, number of gallstones and survival.

Gallstones are a risk factor for the development of gallbladder cancer. We studied DNA ploidy and cell cycle composition by flow cytometry in archival specimens from 52 gall bladder carcinomas in relation to histopathological grade, tumour stage, gallstone number and survival. 69% of the gallbladder carcinomas showed aneuploidy. All tumours with single stones (N=11) were aneuploid while only 61% of tumours with multiple stones (N=41) were aneuploid (p=0.002). DNA aneuploidy was related to increase in T-category (p=0.01), grade (p=0.02), and nuclear pleomorphism (p=0.0005). The distribution of DNA ploidy shifted from tetraploid in low stage towards triploid positions in high stage tumours (p=0.02) combined with higher S-phase values in triploid tumours (p=0.05). S-phase fraction increased during development from normal tissue to dysplasia, cancer in situ and cancer in diploid cases (p=0.0002), and further at the change from diploid to aneuploid (p=0.004). At a median cancer specific survival time of four months patients with diploid tumours had a better survival than those with aneuploid tumours (p=0.02). In multivariate analysis of the tumour characteristic, only T-category and tumour grade were independent prognostic factors.The shift from diploid to aneuploid and the further shift of ploidy within aneuploid tumours are in agreement with the concept of a clonal development of gallbladder cancer. These changes are combined with a stepwise increase in the fraction of S-phase cells. Low frequency of symptoms in single stone patients may be the reason for detection of malignancy at a late stage of tumour development.     

Endocrine profile in gastric carcinomas. An immunohistochemical study.

22 gastric carcinomas (13 intestinal type and nine diffuse type) were immunostained for neuron specific enolase, chromogranin, Leu-7 and a panel of fifteen different peptide hormones. Five out of the 13 tumours of intestinal type and four out of the nine diffuse carcinomas expressed immunoreactivity for one or more of the pan endocrine markers. Seven out of the 13 tumours of intestinal type and five out of the nine diffuse carcinomas also expressed immunoreactivity for gastrin (3), ACTH (3), serotonin (7) and calcitonin (7). Immunoreactivity for somatostatin (1) and substance P (1) were also seen in two tumours of intestinal type. Seven out of 18 cases with benign mucosa adjacent to the tumours expressed a focal immunoreactivity for chromogranin (6), serotonin (6), gastrin (5) and calcitonin (1). All hormone-producing tumours also expressed immunoreactivity for carcino-embryonic antigen. Our results confirm that a high proportion of gastric carcinomas are hormone producing.     

Tetraploid cycle in ageing solid tumours

When the mouse mammary adenocarcinoma 755 (Ca-755) reaches the plateau phase of growth, non-cycling cells with a G2-DNA content can be observed. They may belong to the diploid cell cycle but they could also be blocked in G0 or G1 of a tetraploid cycle. This hypothesis was tested in three ways: (1) non-cycling G2 nuclei were stained with a combination of Feulgen and naphthol yellow which revealed two populations, one with a low protein content and the other with a high protein content--the latter may represent nuclei ready to begin a new phase of DNA synthesis; (2) Feulgen staining and autoradiography were performed after tritiated thymidine had been administered to mice continuously: this showed that there were cells synthesizing DNA with a DNA index above 2; and (3) cells having 80 chromosomes, corresponding to the tetraploid cycle, were found almost exclusively in the plateau phase tumours. On the other hand, the use of texture and DNA parameters of the Feulgen stained nuclei showed that they were concentrated in a diploid cycle for tumours in the exponential phase of growth and were divided between a diploid and tetraploid cycle for 'plateau' cells. Neither the cause for, nor the role played by, polyploid cells is known.     

Tetraploid cycle in ageing solid tumours

Abstract. When the mouse mammary adenocarcinoma 755 (Ca-755) reaches the plateau phase of growth, non-cycling cells with a G₂-DNA content can be observed. They may belong to the diploid cell cycle but they could also be blocked in G₀ or G₁ of a tetraploid cycle. This hypothesis was tested in three ways: (1) non-cycling G₂ nuclei were stained with a combination of Feulgen and naphthol yellow which revealed two populations, one with a low protein content and the other with a high protein content– the latter may represent nuclei ready to begin a new phase of DNA synthesis; (2) Feulgen staining and autoradiography were performed after tritiated thymidine had been administered to mice continuously: this showed that there were cells synthesizing DNA with a DNA index above 2; and (3) cells having 80 chromosomes, corresponding to the tetraploid cycle, were found almost exclusively in the plateau phase tumours.
On the other hand, the use of texture and DNA parameters of the Feulgen stained nuclei showed that they were concentrated in a diploid cycle for tumours in the exponential phase of growth and were divided between a diploid and tetraploid cycle for 'plateau' cells. Neither the cause for, nor the role played by, polyploid cells is known.     

Microspectrophotometry of cell nuclei stained with the Feulgen reaction. IV. Formation of tetraploid nuclei in rat liver cells during postnatal growth

1. DNA contents of the individual parenchymal nuclei of rat livers during postnatal growth were estimated by microspectrophotometric apparatus, and different ploidy classes of nuclei were classified by their DNA contents. With the same material the total number of parenchymal nuclei in the liver was counted microscopically. 2. If the DNA content of nuclei encountered most frequently in several tissues represents the diploid class, the ploidy classes of the rat liver cell nuclei correspond to di-, tri-, tetra-, and octoploid, with the di- and tetraploid ones predominating considerably. 3. In suckling rats (below 25 gm. of body weight) the liver parenchyma is composed almost exclusively of cells with diploid nuclei, whereas in young rats (above 80 gm.), of tetraploid nuclei. In the growth stage between 25 and 80 gm., there is a remarkable replacement of the diploid nuclei by the tetraploid ones. However, in the liver of adult rats weighing more than 150 gm., any increase or decrease in the frequency of diploid and tetraploid nuclei is hardly observable. In such rats, the nuclear population of the liver parenchyma seems to reach a cell-ecological equilibrium which is considered to be a stable one. 4. It is shown that such nuclear populations and the total number of nuclei in a liver are controlled by the growth state, and not by the age. 5. The decrease in the total number of diploid nuclei and the increase in tetraploid nuclei in the growing livers of rats weighing from 40 up to 130 gm. can both be explained by the hypothesis that the tetraploid nuclei originate from the interphase diploid nuclei without involving mitosis. This hypothesis implies that mitosis is confined to the reproduction of diploid cells alone. 6. It is suggested that, in general, the synthesis of DNA does not necessarily result in the formation of visible mitotic chromosomes. 7. Mitotic time and generation time of diploid nuclei and the percentage of the tetraploidization from diploid nuclei are calculated and discussed.     

The cytospectrophotometric study of the DNA content in benign and malignant processes in the breast]

Cytospectrophotometric analysis of DNA content in nuclei of the epithelial cells in fibroadenoma, fibroadenomatous and breast cancer revealed that mean value of DNA content in breast cancer is reliably higher than in benign processes in breast. Modal class in fibroadenoma and fibroadenomatous formed by di- and tetraploid cells, in breast cancer-tetraploid and higher depending on histological structure of tumor. Ratio of aneuploidy is higher in invasive ductal carcinoma and scirrhus [correction of skir] in comparison with invasive lobular carcinoma and other carcinomas, that evidences higher aggressiveness of these tumors.     

Flow-cytometric analysis of the DNA-content in paraffin-embedded tissue from colorectal carcinomas and its prognostic significance.

The nuclear DNA content of 163 colorectal carcinomas was determined by flow-cytometry (FCM) on formalin-fixed, paraffin-embedded tissue. DNA-aneuploidy was found in 97 cases (59.5%), in which no statistically significant correlations with sex, mean age, tumour stage (Dukes and pTNM) and tumour grade were noted. The frequency of aneuploidy was significantly higher in patients less than 70 years of age (p less than 0.01) and in tumours localized in the left colon and rectum (p less than 0.002), irrespective of their stage. The tumours in which different areas could be analysed (n = 80) showed a heterogeneous DNA-ploidy pattern in 18%. Comparison of the DNA content in primary tumours and in lymph node metastases (n = 49) showed a difference in DNA-ploidy in 38% of the DNA-aneuploid tumours, but in only 6% of the DNA-diploid carcinomas (p less than 0.02). DNA-aneuploid carcinomas tended to show a higher rate of local recurrence and were associated with an unfavourable prognosis (p = 0.04) in those patients in which complete resection of their tumours was possible (n = 72). The significantly higher mortality of patients with DNA-aneuploid carcinomas of stage pT3, as well as those with Dukes stage A and B tumours indicates that DNA-aneuploidy may be a stage-independent additional risk factor in colorectal cancer.     

MICROSPECTROPHOTOMETRY OF CELL NUCLEI STAINED WITH THE FEULGEN REACTION : IV. FORMATION OF TETRAPLOID NUCLEI IN RAT LIVER CELLS DURING POSTNATAL GROWTH

1. DNA contents of the individual parenchymal nuclei of rat livers during postnatal growth were estimated by microspectrophotometric apparatus, and different ploidy classes of nuclei were classified by their DNA contents. With the same material the total number of parenchymal nuclei in the liver was counted microscopically. 2. If the DNA content of nuclei encountered most frequently in several tissues represents the diploid class, the ploidy classes of the rat liver cell nuclei correspond to di-, tri-, tetra-, and octoploid, with the di- and tetraploid ones predominating considerably. 3. In suckling rats (below 25 gm. of body weight) the liver parenchyma is composed almost exclusively of cells with diploid nuclei, whereas in young rats (above 80 gm.), of tetraploid nuclei. In the growth stage between 25 and 80 gm., there is a remarkable replacement of the diploid nuclei by the tetraploid ones. However, in the liver of adult rats weighing more than 150 gm., any increase or decrease in the frequency of diploid and tetraploid nuclei is hardly observable. In such rats, the nuclear population of the liver parenchyma seems to reach a cell-ecological equilibrium which is considered to be a stable one. 4. It is shown that such nuclear populations and the total number of nuclei in a liver are controlled by the growth state, and not by the age. 5. The decrease in the total number of diploid nuclei and the increase in tetraploid nuclei in the growing livers of rats weighing from 40 up to 130 gm. can both be explained by the hypothesis that the tetraploid nuclei originate from the interphase diploid nuclei without involving mitosis. This hypothesis implies that mitosis is confined to the reproduction of diploid cells alone. 6. It is suggested that, in general, the synthesis of DNA does not necessarily result in the formation of visible mitotic chromosomes. 7. Mitotic time and generation time of diploid nuclei and the percentage of the tetraploidization from diploid nuclei are calculated and discussed.     

Proteomic evaluation of sheep serum proteins

Background

Mammary tumours frequently develop in female domestic cats being highly malignant in a large percentage of cases. Chemokines regulate many physiological and pathological processes including organogenesis, chemotaxis of inflammatory cells, as well as tumour progression and metastasization. In particular, the chemokine/receptor pair SDF-1/CXCR4 has been involved in the regulation of metastatic potential of neoplastic cells, including breast cancer. The aim of this study was the immunohistochemical defininition of the expression profile of CXCR4 in primary and metastatic feline mammary carcinomas and the evaluation of the role of SDF-1 in feline mammary tumour cell proliferation.

Results

A total of 45 mammary surgical samples, including 33 primary tumours (31 carcinomas and 2 adenomas), 6 metastases, and 4 normal mammary tissues were anlyzed. Tumor samples were collected from a total number of 26 animals, as in some cases concurrent occurrence of neoplasm in more than one mammary gland was observed. Tissues were processed for standard histological examination, and all lesions were classified according to the World Health Organization criteria. CXCR4 expression in neoplastic cells was evaluated by immunohistochemistry. The level of CXCR4 immunoreactivity was semi-quantitatively estimated as CXCR4 score evaluating both the number of positive cells and the intensity of staining. Six primary, fibroblast-free primary cultures were obtained from fresh feline mammary carcinomas and characterized by immunofluorescence for CXCR4 and malignant mammary cell marker expression. SDF-1-dependent in vitro proliferative effects were also assayed. CXCR4 expression was observed in 29 out of 31 malignant tissues with a higher CXCR4 score observed in 4 out of 6 metastatic lesions than in the respective primary tumours. In 2 benign lesions analyzed, only the single basaloid adenoma showed a mild positive immunostaining against CXCR4. Normal tissue did not show CXCR4 immunoreactivity. CXCR4 score was statistically significantly associated with the histological features of the samples, showing an increase accordingly with the degree of neoplastic transformation (from normal tissue to metastatic lesions). Finally, in the primary cultures obtained from 6 primary feline mammary carcinomas CXCR4 expression was detected in all cells and its activation by SDF-1 in vitro treatment caused a significant increase in the proliferation rate in 5 out of 6 tumours.

Conclusions

These results indicate that malignant feline mammary tumours commonly express CXCR4, with a higher level in malignant tumours, and, in most of the cases analysed, metastatic cells display stronger immunoreactivity for CXCR4 than the corresponding primary tumours. Moreover, CXCR4 activation in primary cultures of feline mammary carcinomas causes increase in the proliferative rate. Thus, SDF-1/CXCR4 system seems to play a tumorigenic in feline mammary gland malignancy and in vitro cultures from these tumour samples may represent an experimental model to investigate the biological and pharmacological role of this chemokinergic axis.     

Nuclear DNA in histologic sections from squamous-cell carcinoma and adenocarcinoma of the lung

The nuclear DNA content in morphologically identified tumor cells was analyzed in 4-micron histologic sections from 58 patients with lung carcinoma who survived for at least five years. Thirty-three of the carcinomas were invasive squamous bronchial carcinomas and 25 were pulmonary adenocarcinomas. In all squamous carcinomas, the majority of tumor cells were found to exhibit DNA values exceeding the normal tetraploid and/or diploid region. In contrast, some of the pulmonary adenocarcinomas were found to be composed of a majority of tumor cells with DNA values in the normal diploid region. The results indicate that invasive squamous bronchial carcinomas, in general, are tumors with aneuploid DNA patterns indicative of a high malignant potential and that malignancy grading based on DNA measurements does not add any significant prognostic information to that obtained by morphologic diagnosis.     

Prognostic value of flow cytometrically determined DNA-ploidy, intracellular pH and esterase activity of non-small cell lung carcinomas.

30 surgical specimens of patients with non-small cell lung carcinomas (NSCLC) were investigated. Significant increases of intracellular pH values in epithelial and inflammatory cells, in the percentage of dead epithelial and inflammatory cells and in the cell volume of vital inflammatory cells in cancerous lung tissue were encountered. Furthermore, decreases of the esterase activity of vital epithelial cells and of the percentage of free cell nuclei were observed. The DNA aneuploidy in 36.6% of the tumours was frequently associated with non-squamous cell carcinomas and stage II, III, IV tumours. Patients with DNA aneuploid tumours had a significantly shorter survival rate than those with DNA euploid tumours. Within the different tumour stages a similar tendency was observed which was, however, only significant in stage III tumour patients. Stage III tumours constitute therefore a heterogeneous entity with a worse prognosis for DNA aneuploid tumour patients. The intracellular pH values and esterase activity as well as the cell volume, the percentage of free cell nuclei and dead inflammatory or epithelial cells contained no significant prognostic information.     

Dry mass, DNA and non-histone protein determinations in lung cancer cells

Summary Cell nuclei from two biopsies of bronchial mucosa, seven squamous-cell carcinomas and six small-cell carcinomas of the lung were investigated. DNA and non-histone protein (NHP) content were simultaneously determined in Feulgen—Naphthol Yellow S-stained smears by means of multiple plug cytophotometry. In addition, the nuclear dry mass of cells originating from the same populations was measured by interference microscopy.DNA histograms of carcinomas were characterized by DNA stemlines being situated in the diploid range in four out of six small-cell carcinomas and in the hyperdiploid to hypertetraploid range in six out of seven squamous-cell carcinomas.Polyploid values (up to 8 c) were seldom found in small-cell carcinomas whereas squamous-cell carcinomas showed a broader dispersion approaching the 16 c level.The similarity of the NHP distributions with the DNA histograms was more marked in small-cell carcinomas than in the squamous-cell carcinomas. In comparison with the NHP distributions of normal bronchial epithelial cells, those of carcinomas were shifted to higher values. The increased NHP content was found to be a more prominent sign of malignancy in small-cell carcinomas than the DNA mass. The increase in nuclear dry mass in carcinomas was mainly caused by the accumulation of NHP in tumour cell nuclei.     

Flow-cytometric analysis of the DNA-content in paraffin-embedded tissue from colorectal carcinomas and its prognostic significance

The nuclear DNA content of 163 colorectal carcinomas was determined by flow-cytometry (FCM) on formalin-fixed, paraffin-embedded tissue. DNA-aneuploidy was found in 97 cases (59.5%), in which no statistically significant correlations with sex, mean age, tumour stage (Dukes and pTNM) and tumour grade were noted. The frequency of aneuploidy was significantly higher in patients less than 70 years of age (p < 0.01) and in tumours localized in the left colon and rectum (p< 0.002), irrespective of their stage. The tumours in which different areas could be analysed (n = 80) showed a heterogeneous DNA-ploidy pattern in 18%. Comparison of the DNA content in primary tumours and in lymph node metastases (n = 49) showed a difference in DNA-ploidy in 38% of the DNA-aneuploid tumours, but in only 6% of the DNA-diploid carcinomas (p<0.02). DNA-aneuploid carcinomas tended to show a higher rate of local recurrence and were associated with an unfavourable prognosis (p = 0.04) in those patients in which complete resection of their tumours was possible (n = 72). The significantly higher mortality of patients with DNA-aneuploid carcinomas of stage pT3, as well as those with Dukes stage A and B tumours indicates that DNA-aneuploidy may be a stage-independent additional risk factor in colorectal cancer.     

Superficial urothelial (umbrella) cells. A potential cause of abnormal DNA ploidy results in urine specimens

OBJECTIVE: To determine the DNA ploidy distribution in urothelial superficial (umbrella) cells and to assess the value of the image analysis operator's experience. STUDY DESIGN: DNA ploidy was assessed in 12 cytologically negative bladder washes stained with Feulgen stain. All 12 cases were evaluated independently by three operators with different levels of cytopathology experience and different goals. Operator 1 (experienced) selected only nuclei of urothelial cells, avoiding nuclei of superficial cells; operator 2 (experienced) selected only nuclei of superficial cells; operator 3 (inexperienced) selected the largest and most-atypical-looking nuclei. Each operator measured a total of 100 nuclei per case. RESULTS: Operator 1 found all cases to be diploid (97% of nuclei on average). Operators 2 and 3 showed a wide range of results. Almost half the nuclei (47%) analyzed by operator 2 were in the diploid region, a third (35%) were in the tetraploid region, and the remaining (18%) ones had a DNA index (DI) in the range of 1.2-1.8 or > 2.5. Operator 3 obtained the most abnormal results. Only 9% of the nuclei were diploid, while 37% were in the tetraploid region, 18% were in the hyperploid region, and 35% had a DI in the range of 1.2-1.8. Differences among results obtained by each operator were statistically significant. CONCLUSION: The nuclei of superficial (umbrella) cells often have abnormal DNA content, which may cause abnormal DNA ploidy results in cytomorphologically normal bladder washes. Consequently, the nuclei of superficial cells should be avoided in the evaluation of urine samples. DNA analysis of urine specimens requires selection of nuclei only of deep urothelial cells by an experienced operator.     

Pure and mixed mucinous carcinoma of the breast: fine needle aspiration cytology findings and review of the literature

J. Cyrta, F. Andreiuolo, S. Azoulay, C. Balleyguier, C. Bourgier, C. Mazouni, M.‐C. Mathieu, S. Delaloge and P. Vielh
Pure and mixed mucinous carcinoma of the breast: fine needle aspiration cytology findings and review of the literature Objective: Mucinous (colloid) breast carcinoma accounts for 1–6% of all breast cancer. It comprises pure mucinous tumours and mixed infiltrating ductal carcinomas with a mucinous component. As this latter mixed form has a worse prognosis than pure colloid carcinoma, making this diagnosis on fine needle aspiration cytology (FNAC) might influence the choice of treatment. Methods: We report a consecutive series of 22 cases consisting of 17 mixed and five pure mucinous carcinomas diagnosed by cytology and verified on histopathology. Patients underwent FNAC at the one‐stop clinic of our institution during a 7‐year period of time. Cytological findings were evaluated by a semi‐quantitative method and included percentage of smear surface occupied by mucin, shape of cell groupings, size and outline of tumour nuclei as well as presence or absence of nucleolus. Results: Three of five pure mucinous carcinomas displayed at least two of the following features: abundant mucin, small nuclei and/or regular nuclear outlines. Sparse mucin, large nuclei, irregular nuclear outlines or the presence of nucleoli were found in 7 out of 17 mixed mucinous carcinomas but not in pure tumours. Conclusion: Cytopathological identification of patients with pure mucinous carcinomas may be performed in a limited number of cases.     

Correlation of DNA distribution and cytological differentiation of human cervical carcinomas

The DNA distribution of biopsy specimens from 46 patients suffering from cervical carcinoma was analysed by flow cytometry and compared with the cytological differentiation. According to morphological criteria the carcinomas were classified as highly differentiated, moderately differentiated and poorly differentiated. The results demonstrate that highly differentiated tumours contain hyperploid cells predominantly with hyperdiploid DNA content. Hyperploid cell populations in the moderately differentiated tumours are mainly in the hyperdiploid and tetraploid regions. Poorly differentiated tumours contain hypertetraploid and aneuploid cell populations. The significance of these findings is discussed.     

Tumour ploidy, morphometry, histological grading and clinical features in ovarian carcinoma: mutual relations

The relationship between tumour ploidy and qualitative and quantitative histopathology was assessed in a series of 95 ovarian carcinomas. 67% of the tumours were non-diploid (DNA aneuploid). 56% of the early stage (I-II) tumours were non-diploid and 81% of the tumours in advanced (III-IV) stages were aneuploid. Histological grading failed to show a clear relationship between increasing malignancy grade and ploidy. There was a close association between DNA ploidy and nuclear perimeter, area and shortest and longest nuclear diameter: the nuclei of non-diploid tumours were generally larger. Also the number of mitotic figures per square millimeter of epithelium in the microscope image (volume-corrected mitotic index, M/V-index) differed significantly between near-diploid and non-diploid tumours. Discriminant analysis showed that 74% of the learning-set tumours (67% of the test set tumours) could be correctly classified in low-ploidy and high-ploidy categories with morphometric features (nuclear perimeter, M/V-index and volume percentage of epithelium). Characteristic features of non-diploid ovarian tumours--rapid proliferation and large nuclear size--could be assessed with morphometric methods which allowed a relatively large aneuploid tumour group to be distinguished.     

Presence of specific mutation of Ha-ras oncogene in skin tumors of mice induced under different experimental conditions

The mutation was revealed with substitution of A for T in the second position of the 61 Ha-ras oncogene codon in the DNA of 31 skin tumours (26 papillomas and 5 carcinomas) and in 23 mice treated with 12-O-tetradecanoyl phorbol-13-acetate (TPA). Part of these mice were F progeny (n-6) and F progeny (n-4) following DMBA administration during pregnancy, another part F progeny (n-5) following ENU action on males prior to mating, the rest mice (n-3) did not undergo additional actions. The mutation under study was revealed only in 3 out of 5 papillomas and in all 5 carcinomas of mice subjected to DMBA administration during pregnancy.     

A cytophotometric analysis of the structure of hypothalamic cell populations in the frog,Rana temporaria (L.), with special reference to seasonal changes in chromatin status

Summary We used cytophotometry after the Feulgen reaction and UV cytophotometry to measure the DNA content of quiescent cells of the hypothalamic preoptic region (HPR) of adult and juvenile frogs (Rana temporaria) that had been caught in their natural habitat in winter, spring and summer. The histone-to-DNA ratio in cell nuclei was cytophotometrically determined using a combined Feulgen, heparine and alcian-blue staining procedure. The vast majority of HPR cells studied had nuclei with a diploid DNA content. However, we observed great variability in the Feulgen-DNA content of the HPR cell population, which was not detected in the diploid standard (hepatocytes). This heterogeneity in the diploid sample of the HPR cell populations was always greater in prespawning frogs and may have been due to differences in the chromatin arrangement in nuclei. About 1% of cells had a DNA content either ranging between diploid and tetraploid levels (H2C cells) or at the tetraploid level (4C and 2C x 2 cells). The proportion of these cells was not affected by the age of the animals or the annual cycle, thus suggesting that there is no age-related increase in the mean DNA content in the frog HPR. The mean DNA contents of H2C and 4C cells were much higher than those in the standard (hepatocytes). This cannot be simply attributed to the presence of different amounts of nuclear proteins, but rather indicates that at least a certain proportion of the highest DNA contents may be due to a real extra-DNA synthesis.Dedicated to Professor Dr. T.H. Schiebler on the occasion of his 65th birthday