Morphometry of the FRTL-5 cells after irradiation.

The morphological changes of in vitro irradiated FRTL-5 cells and their ability to grow in semi-solid medium were studied morphometrically. FRTL-5 cells were grown in medium with 4 different concentrations of TSH (0, 0.1, 1, 10 mU/ml). After irradiation with 0 Gy, 2 Gy and 4 Gy, the cells were seeded on glass cover-slips and in methocel. Fourteen days after irradiation, the morphometric analysis of FRTL-5 cells and their nuclei was performed. The results showed that irradiation and different doses of TSH have influence on FRTL-5 cell size, more on their nuclei than on the cells as a whole. Growing of FRTL-5 cells in the methocel indicates the possible transformation of these cells after long-culturing in the TSH medium and after irradiation.

Morphology of FRTL-5 cell colonies in a semi-solid medium.

For the first time, 3, 7 and 10 days growth of normal thyroid follicular FRTL-5 cell colonies in a semi-solid medium of 0.6% methocel over 1% agar base was morphometrically analyzed. It was found that the areas of FRTL-5 colonies as well as their perimeters and maximum diameters increased, while according to their form factors the FRTL-5 colonies were regular in shape. After 10 days in a semi-solid medium, 83% of the FRTL-5 colonies had maximum diameters greater than 50 microm. It is obvious that after long culturing of FRTL-5 cells under the influence of the pituitary thyroid-stimulating hormone (TSH) these cells are not uniform anymore and that they grow in a semi-solid medium.

Astereological analysis of the FRTL-5 cells up to four days after trypsinisation.

FRTL-5 cells grow as a monolayer culture in vitro and they must be detached from the solid surface by trypsin before reseeding. The aim of this study was to examine by light microscopy and by the astereological method the changes that occur in FRTL-5 cells one, two, three or four days after trypsinisation. The most pronounced qualitative and quantitative changes were seen from the first to the second day after trypsinisation, as the area of the cells increased by 119%, their nuclei by 71% and the cytoplasm by 150%, while the nuclear-cytoplasmic ratio decreased by 42%. Significant increases in the average area of the cells, their average nuclear diameter and perimeter were seen also on the third and fourth days, while the average nuclear-cytoplasmic ratio decreased significantly on the first three days after trypsinisation and then remained constant.

Measurement characteristics of stereological and histochemical methods in the diagnosis of thyroid tumours.

Seventy-two female mice of BALB/c strain were divided into three control and three perchlorate groups. The perchlorate groups drank 1.2% sodium perchlorate solution. After 8 or 32 weeks of the 46-week experiment one control and one perchlorate group were totally irradiated with 0.8 Gy on 5 consecutive days. Ten normal thyroid glands, 10 with hypertrophy and hyperplasia, 8 follicular adenomas and 10 follicular carcinomas were histologically and stereologically analysed. The results showed significant differences in the average nuclear volume (p < 0.05) and in the average number of the silver-stained nucleolar organiser regions (AgNORs) per nucleus (p < 0.005) between the follicular adenomas and the follicular carcinomas. The method of counting Ag-NORs per nucleus was more valid, more accurate and more economical than the method of measuring the average nuclear volume.

Ag-NOR counting for differentiation of follicular thyroid tumours.

According to the histological typing system of thyroid tumours adapted by the World Health Organisation follicular tumours are classified as follicular adenomas and follicular carcinomas. The most important diagnostic criterion for follicular carcinoma is the evidence of vascular and/or capsular infiltration. The aim of this work was to verify the Ag-NOR counting method for the diagnosis of thyroid tumours. From the material of the experiment on mice that drunk thyrostatic (1.2% NaCIO4) and were irradiated 10 histologically normal thyroids, 10 showing hypertrophy and hyperplasia, 8 follicular adenomas and 10 follicular carcinomas were used. Thyroid glands were impregnated with the silver to present Ag-NORs. The average numbers of Ag-NORs per nucleus (Ag-NOR/nucleus) for each group were determined. The results showed that the method of counting Ag-NOR can be used to differentiate among thyroid tumours.

The long-term effect of a calcium diet on the bone tissue, C-cells and parathyroid glands of the rat.

In this experiment of 11 month-duration, 18 female Wistar rats received controlled amounts of calcium with food and water, to produce a state of either hypocalcemia or hypercalcemia. After a long-term low calcium diet hypocalcemia disappeared. This group of animals showed insignificant increases in the nuclear-cytoplasmic ratio of the parathyroid cells as well as in the total volume of the parathyroid glands, and a significant increase in the volume density of the osteoid. In the group receiving a high calcium diet, hypercalcemia was still present after 11 month. The insignificantly smaller and more numerous C-cells produced more calcitonin than normally. The parathyroid cells were significantly smaller and the numerical areal density of the osteoclasts was significantly lower than in the control group. It can be concluded that the parathyroid glands and C-cells are involved in the maintenance of blood calcium homeostasis during a long-term experiment on rats receiving low or high calcium diet.

The effect of sodium perchlorate and ionizing irradiation on the thyroid parenchymal and pituitary thyrotropic cells.

In a 46-week-experiment on 72 female mice the influence of peroral 1.2% sodium perchlorate application, total ionizing irradiation with 8 Gy on 5 consecutive days and their interaction on the pituitary-thyroid axis was studied by histological and stereological methods. It was observed that perchlorate alone caused long-term and strong hypothyroidism with hypertrophic and hyperplastic thyroid epithelial cells as well as pituitary thyrotropic cells. When only irradiation was used, no uniform changes in the structure and function of these cells could be detected. The interaction of perchlorate and irradiation showed similar effects as thyrostatics alone, with some exceptions; paradoxically, minor hyperplasia of thyrotropic as well as of parafollicular cells was observed. A high percentage of the follicular cell carcinoma was found after perchlorate application and after its combination with irradiation. No medullary carcinoma was found.

The effect of chronic hypercalcemia or hypocalcemia on the follicular and parafollicular cells in rat thyroid gland.

In three experiments of 30 weeks' duration, 93 adult female Wistar rats received controlled amounts of calcium with food and water, to produce a state of either hypercalcemia or hypocalcemia. A systematic stereological analysis of the thyroid glands and a radioimmunological analysis of thyroxine, triiodothyronine, and thyrotropine were performed. In the hypercalcemic rats, a reactive hyperplasia of the parafollicular cells was established; this was accompanied by morphological and biochemical signs of hyperfunction of the follicular cells, despite a reduced central stimulation by thyrotropin. In the hypocalcemic animals, no quantitative morphological changes in the parafollicular cells were observed; however, morphological and biochemical signs of hypofunction of the follicular cells were obvious, despite stronger central stimulation by thyrotropin. It is concluded that the extrinsic regulation of follicular cells by the blood calcium level is stronger than the intrinsic regulation by hypothalamo-hypophyseal hormones.

The interdependence of the follicular, parafollicular, and mast cells in the mammalian thyroid gland: a review and a synthesis.

The aim of this paper is to summarize some of our quantitative descriptive and experimental studies, to discuss them in view of the literature data, and to present a synthesis of the topic. The results of stereological analysis of some tissue components of the rat thyroid gland have been compared with the results of topological studies on the parafollicular cells of various mammalian species. Localization of the parafollicular cells in the central regions of the thyroid gland lobes, where the follicular cell activity seems to be greater than in the periphery of the lobes, has led to the hypothesis that the parafollicular cells regulate (stimulate and/or suppress) the activity of the follicular cells. Long-term application and antithyroid drugs to mice and rats has shown that excessive concentrations of thyrotropin provoke hyperplasia of both the follicular cells and the intrathyroid mast cells and, transiently, of the parafollicular cells. This and some of the literature data are congruent with the hypothesis that the parafollicular and mast cells also stimulate the follicular cells by their paracrine secretions. Long-term application of antithyroid drugs to mice and rats has shown that excessive concentrations of cular cells but also probably stimulation of the follicular cells, as judged by the stereological measurements. The biological meaning of the spatial integration of follicular and parafollicular cells seems to be a functional coordination of both epithelial cell lines, supported by intrathyroid mast cells.

Carcinogenesis after sublethal ionizing irradiation and regular avoidance irritation.

160 mice of the BALB/C strain of both sexes, aged 3 months, were divided into four equal groups out of which two were regularly irritated by a combination of an optical signal and electrical stroke. After one month of irritation one nonirritated and one irritated group were whole body irradiated with a single dose of 6.65 Gy (1.83 Gy/min), the other two groups were sham irradiated. The mice lived until their spontaneous death or one year after irradiation, respectively, when the rest of the animals were sacrificed. The appearance of malignant tumors was noted. Irradiation shortened the survival time while the irritation had an appeasing, compensatory effect, more expressed in the males than in the females. After irradiation the number and assortment of the tumors increased and the latent period essentially shortened. In the irritated animals the number and assortment of the malignant tumors were reduced and a tendency for lengthening of the latent time period was seen; these differences, however, were not statistically significant. In spite of some differences the response in both sexes to irradiation and irritation or their combination was similar.