Height Of Follicular Epithelium Research Articles

EFFECT OF INTERVAL FASTING ON MORPHOLOGICAL CHANGES IN THE RAT THYROID GLAND OF DIFFERENT AGE

Despite of the well-studied effect of interval fasting on the body, literature data on its infl uence on functional activity and, especially, on morphological changes in the thyroid gland are sporadic. The research results are often contradictory, which may be due to differences in experimental conditions. The aim of this study was to investigate the morphological changes in the rat’s thyroid gland of different ages, which were on interval fasting. The experiments were performed on 48 male Wistar rats aged 4 and 16 months. The experimental rats underwent interval fasting (1 day complete fasting / 2 days standard diet). Duration of experiment was 28 days. Thyroid tissue preparations were made according to standard histological methods. The morphometry was performed on digital images using a computer program Image J. It was found that the colloid area, the interior diameter of the follicles and colloid accumulation index were decreased in 4 and 16 month-old rats after interval fasting. The relative connective tissue area was also decreased in 16-month- old rats. But the follicular epithelium height, the follicular-colloidal index and the number of interfollicular islets were increased. The morphological changes of the thyroid gland tissue in 16-month-old experimental rats were manifested to a greater extent than in young animals. Thus, after exposure to interval fasting, morphological signs of activation of the thyroid gland synthetic activity in rats of different ages were observed. Key words: interval fasting, thyroid gland, morphometric indicators.

Adverse effects of high-dose paracetamol on thyroid gland of female rats

Aim: The aim of this study is to determine whether paracetamol, an analgesic whose mechanism of action is not yet fully known but used unconsciously, causes toxicity on the thyroid gland.Materials and Methods: A total of 25 female Wistar albino rats divided into five groups as Control (C), Paracetamol 7 days (P7), Paracetamol 14 days (P14), Paracetamol 21 days (P21) and Paracetamol 28 days (P28). The Paracetamol groups were given 750 mg/kg/day paracetamol via oral gavage administration until the day they were sacrificed. Routine histological procedures were applied to the removed thyroid glands. Thyroid tissue sections were evaluated morphometrically and histopathologically.Results: Cytoplasmic vacuolization and deterioration in follicle and colloid structures were detected in follicular epithelial cells in thyroid tissue sections of groups given paracetamol. The mean of follicle diameter measurement of the P7 group was significantly decreased compared to the control group (p<0.05). In all paracetamol groups, the mean follicular epithelium height increased significantly compared to the control group (p<0.05).Conclusion: These results show that high doses of paracetamol cause toxic effects on the thyroid gland depending on the duration of use.

The influence of the lack of insulin receptor substrate 2 (IRS2) on the thyroid gland

Involvement of IRS2 in the proliferative effects of IGF-I of follicular thyroid cells has been described, but there are no evidences for in vivo participation of IRS2. This study aimed to analyse the in vivo relevance of IRS2 in the proliferation and apoptosis of thyroid cells by immunocytochemical studies for PCNA, Ki67, and active-caspase-3 in thyroid cells of IRS2 knockout (IRS2-KO) mice, jointly to TUNEL assay. Thyroid hormones were lower in IRS2-KO mice than in their wild-type (WT) counterparts. Increases in the area, perimeter and diameter of thyroid follicles of IRS2-KO mice were observed, which also showed increased proliferation rate of follicular cells and decreased percentage of apoptotic cells that was more evident in the central than in the marginal region of the gland. Sex-related differences were also found, since the follicular epithelium height was higher in male than in female mice. The percentage of proliferating cells showed significant changes in male but not in female mice, and apoptotic cells were more abundant in female than in male IRS2-KO animals, without significant differences between WT-animals. Therefore, our results suggest that IRS2 could be involved in the maintenance of thyroid cells population and in the normal physiology of the thyroid gland.

Growth performance, morphometric analysis of the intestinal mucosa and thyroid of broiler fed canola meal

ABSTRACT The aim of this study was to evaluate the effect of replacing soybean meal with canola meal in broiler diets on performance, liver histopathology, morphometry of the intestinal mucosa and thyroid. One-day-old Cobb chicks (n=300) were distributed in a completely randomized design, with increasing levels of replacement of soybean meal with canola meal (0, 25, 50, 75 and 100%) and 6 repetitions of 10 birds each. Weight gain decreased linearly (P< 0.05) with increasing levels of inclusion of canola meal, in all stages. Villus height in the duodenum and jejunum linearly decreased (P< 0.05). Follicle diameter and thyroid follicular epithelium height increased linearly with increasing levels of canola meal (P< 0.05). Similarly, there was an increase in relative weight of liver and heart, and liver steatosis in the highest levels of replacement. In conclusion, the replacement of soybean meal with canola meal can reduce performance, adversely affecting the thyroid, liver and the morphometric characteristics in the duodenum and jejunum.

Stereoselective degradation and thyroid endocrine disruption of lambda-cyhalothrin in lizards (Eremias argus) following oral exposure

The disturbance of the thyroid system and elimination of chiral pyrethroid pesticides with respect to enantioselectivity in reptiles have so far received limited attention by research. In this study, bioaccumulation, thyroid gland lesions, thyroid hormone levels, and hypothalamus-pituitary-thyroid axis-related gene expression in male Eremias argus were investigated after three weeks oral administration of lambda-cyhalothrin (LCT) enantiomers. In the lizard liver, the concentration of LCT was negatively correlated with the metabolite-3-phenoxybenzoic acid (PBA) level during 21 days of exposure. (+)-LCT exposure induced a higher thyroid follicular epithelium height than (−)-LCT exposure. The thyroxine levels were increased in both treated groups while only (+)-LCT exposure induced a significant change in the triiodothyronine (T3) level. In addition, the expressions of hypothalamus-pituitary-thyroid axis-related genes including thyroid hormone receptors (trs), deiodinases (dios), uridinediphosphate glucuronosyltransferase (udp), and sulfotransferase (sult) were up-regulated after exposure to the two enantiomers. (+)-LCT treatment resulted in higher expression of trs and (−)-LCT exposure led to greater stimulation of dios in the liver, which indicated PBA-induced antagonism on thyroid hormone receptors and LCT-induced disruption of thyroxine (T4) deiodination. The results suggest the (−)-LCT exposure causes higher residual level in lizard liver while induces less disruption on lizard thyroid activity than (+)-LCT.

Testosterone and estradiol treatments differently affect pituitary-thyroid axis and liver deiodinase 1 activity in orchidectomized middle-aged rats

We previously reported that orchidectomy (Orx) of middle-aged rats (15–16-month-old; MA) slightly affected pituitary-thyroid axis, but decreased liver deiodinase (Dio) type 1 and pituitary Dio2 enzyme activities. At present, we examined the effects of subsequent testosterone-propionate treatment (5mg/kg; Orx+T), and compared the effects of testosterone with the effects of estradiol-dipropionate (0.06mg/kg; Orx+E) treatment. Hormones were subcutaneously administered, daily, for three weeks, while Orx and sham-operated (SO) controls received only the vehicle. The applied dose of T did not alter serum TSH, T4 and T3 concentrations in Orx- MA, though it increased TSH when administrated to Orx young adults (2.5-month-old; Orx-YA). However, pituitaries of Orx–MA+T rats had higher relative intensity of immunofluorescence (RIF) for TSHβ; in their thyroids we found increased volume and height of follicular epithelium, decreased volume of the colloid and higher RIF for T4-bound to thyroglobulin (Tg-T4). Liver Dio1 activity was increased. E-treatment did not affect serum hormone levels, pituitary RIF for TSHβ, or liver Dio1 activity in Orx-MA rats. Thyroids had decreased relative volume and height of follicular epithelium, increased relative volume of the colloid, decreased volume of sodium-iodide symporter-immunopositive epithelium and lower RIF for Tg-T4. Detected changes were statistically significant. In conclusion, androgenization enhanced pituitary TSHβ RIF, thyroid activation and liver Dio1 enzyme activity in Orx-MA, without elevating serum TSH as in Orx-YA rats. Estrogenization induced pituitary enlargement with no effect on pituitary TSHβ RIF, serum TSH or liver Dio1 activity. E also induced alterations in thyroid histology that indicate mild suppression of its functioning, and contributed to thyroid blood vessel enlargement in Orx-MA rats.

Administration of Thyroxine Affects the Morphometric Parameters and VEGF Expression in the Uterus and Placenta and the Uterine Vascularization but does Not Affect Reproductive Parameters in Gilts During Early Gestation

The aim of this study was to evaluate the effects of thyroxine administration on morphometric parameters, expression of vascular endothelial growth factor (VEGF) and vascularization in the uterus and placenta and reproductive parameters in gilts at 70 days of gestation. At 150 days of age, i.e., before first heat, 20 gilts were randomly divided into two experimental groups: treated (n=10) and control (n=10). The treated group received a daily dose of 400 μg of L-thyroxine (T(4)) in their diet until slaughter and the control group received only typical meals. Before artificial insemination, blood was collected to determine plasma total T(4). The gilts were inseminated in the second oestrus and slaughtered at 70 days of gestation. The foetal thyroid follicular epithelium height, number, size and weight of foetuses; foetal myogenesis, corpora lutea number, embryonic mortality rate, uterine weight, placental weight and placental fluid volume were measured. Histomorphometric and immunohistochemical analysis of uterus and placenta were determined. The averages of all variables were compared by the Student's t-test. The gilts treated with thyroxine showed significant increase of plasma total T(4). At 70 days of gestation, the heights of the trophoblastic epithelium, endometrial epithelium and endometrial gland epithelium were significantly higher in the group treated with T(4). The expression of cytoplasmatic and nuclear VEGF in trophoblastic cells and the number of blood vessels per field in endometrial stroma were significantly higher in the gilts treated with T(4). No other significant differences between groups were obtained with respect to other parameters (p>0.05). We conclude that oral administration of T(4) up to 70 days of pregnancy in gilts affects the morphometric parameters, the expression of placental VEGF and the uterine vascularization but does not affect reproductive parameters in gilts during early gestation.

Ability of the Hershberger assay protocol to detect thyroid function modulators

In vivo screening methods for detection of thyroid function modulators are now under development in many research laboratories. We assessed the applicability of the Hershberger assay protocol to screen for thyroid function modulators. In experiment 1, castrated male BrlHan WIST@Jcl (GALAS) rats were administered a potent thyroid peroxidase inhibitor, 3-amino-1,2,4-triazole (AT), in doses of 0, 40, 200, and 1,000 mg/kg/day with gravimetric endpoint, and in experiment 2, castrated and intact male rats were administered in doses of 0, 40, and 200 mg/kg/day, with quantification of the extent of hypertrophy of the thyroid epithelium, to assess the effects of castration, by gavage to 8-week-old for 10 consecutive days. At necropsy of both experiments, the thyroid glands and hypophysis were collected and fixed with 10% neutral-buffered formalin. To avoid crushing during weighing because of their fragility, the thyroid glands and hypophysis were weighed approximately 24 h after fixation with 10% neutral-buffered formalin. All animals were sacrificed approximately 24 h after the final dose. In experiment 2, the thyroid glands of all animals were stained with hematoxylin and eosin for histological examination and morphometry of follicular epithelial height. In experiment 1, absolute and relative thyroid weights in all of the AT groups were statistically increased in a dose-dependent manner, regardless of the testosterone propionate (TP)-injection. In experiment 2, the results showed a significant increase in thyroid weight in the 200 mg/kg groups of both castrated and intact rats. Hypophyseal weight was unaltered by AT, but comparison of vehicle-treated groups showed that the hypophyseal weight of the castrated rats was greater than that of the intact rats. Enlarged thyroid glands were observed in the AT-treated rats at necropsy. Histological examination of the thyroid glands of all the AT-treated animals showed hypertrophy and hyperplasia of the follicular epithelial cells, and the height of follicular epithelium of the thyroid glands increased in a dose-dependent manner in both the castrated and intact rats. In experiment 1, assessment of the (anti-) androgenic action of AT in seminal vesicle weight revealed a significant increase in the 200 and 1,000 mg/kg + TP groups in a dose-dependent manner. These results suggest that the effect of AT can be detected by the Hershberger assay 10-day administration protocol and may be useful for screening for thyroid function modulators regardless of whether the animals have been castrated.

Effect of calcium on structural and morphometric features of thyroid gland tissue in middle-aged rat females

The subject of these studies was the thyroid gland tissue of middle-aged (14-month-old) female rats chronically treated with calcium glucoheptonate. The peripheral and central zone of the thyroids were stereologically analysed and the following morphometric parameters determined: the height and volumetric density of follicular epithelium, colloid, interstitium and follicles and index of activation rate. The height of follicular epithelium, its volume density and index of activation rate were significantly reduced (by 8%, p < 0.05, 18%, p< 0.025 and 34%, p < 0.01, respectively) as compared to the controls. However the volumetric density of colloid and interstitium were increased (by 10% and 14% respectively). These morphometric results indicate that Ca treatment expressed an inhibitory effect on thyroid follicular cells structure in middle-aged female rats.

Altura do epitélio folicular da tireóide na triagem para detecção de resíduos de antitireoidianos em bovinos

A altura do epitélio folicular da tireóide, mensurada em secções histológicas coradas pela hematoxilina e eosina, foi testada como característica de triagem para a pesquisa química de resíduos de antitireoidianos em 53 bovinos. Cinco glândulas, contendo resíduos detectados por cromatografia de camada delgada de alta resolução (HPTLC), eram provenientes de cinco novilhos experimentalmente tratados com suspensão oral de metiltiouracil (5g/animal/dia), durante 20 dias, interrompido cinco dias antes do abate. As demais glândulas, sem resíduos detectados por HPTLC, provinham de seis controle experimentais que receberam apenas placebo e de 42 animais abatidos em matadouros industriais de Minas Gerais (n=25) e Goiás (n=17). Todas as glândulas positivas apresentaram hiperplasia intensa e a altura do epitélio folicular foi significativamente maior, embora as 42 glândulas negativas também se mostrassem moderadamente hiperplásicas. Com base nas respostas típicas individuais de 47 tireóides com bócio parenquimatoso e de seis histologicamente normais, ficou estabelecido o limite de 16mim para a altura do epitélio, acima do qual toda glândula deverá ser considerada suspeita e testada quimicamente. Foi determinada a correlação entre a altura do epitélio folicular e outras características indiretas de detecção de resíduos, concluindo-se que a altura do epitélio presta-se para a triagem de programas oficiais de controle de resíduos de drogas antitireoidianas na carne.

Thyroid regeneration in various localizations of the resected fragments of the organ

Structure and function of the regenerating thyroid fragment were studied in 18 adult white rats 30 days after partial resection of centromedial or peripheral fragments of the lobes similar in size using quantitative methods (organometry, histometry, measurements of blood serum hormones). The volume of glandular tissue removed in two series of experiments was 40 and 75% of the total thyroid mass of experimental animals. Centromedial portions of the thyroid of intact rats were characterized by greater follicular epithelium volume (by 10%) and C-cell content per section area (six-fold), as well as by a lesser mean diameter of the follicles (by 26%) and colloid volumic fraction (by 40%) in comparison with the peripheral segments. No reliable differences in the quantitative structural parameters (mass, tissue component volumic fractions, mean follicular diameter and follicular epithelium height) and hormonal activity of the regenerated tissue in the two variants of surgery were observed. The results indicate that thyroid parenchyma of various portions of the organs is similarly capable of full-value regeneration.

Tissue calmodulin levels in normal and Graves' thyroids.

Calmodulin levels in normal human thyroids and Graves' disease thyroids were measured by specific radioimmunoassay in the presence of ethyleneglycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). The calmodulin levels in tissues from patients with Graves' disease treated with thionamide drugs were significantly higher than those in normal tissues from euthyroid patients with solitary cold nodules (normal: 484 +/- 50 ng/mg protein, mean +/- SE, n = 15; Graves': 901 +/- 54 ng/mg protein, n = 48, p less than 0.001). Such a rise in calmodulin levels in Graves' disease thyroids was also present even after the administration of 50 micrograms of T3 for 5 days before operation (828 +/- 137 ng/mg protein, n = 6, p less than 0.01). Calmodulin levels in Graves' disease thyroids were closely related to the cell height of follicular epithelium. Calmodulin levels in a columnar cell predominant group were significantly higher than those in a flat cell predominant or a cuboidal cell predominant group (columnar cell predominant: 1150 +/- 118 ng/mg protein, n = 13; flat cell predominant: 561 +/- 125 ng/mg protein, n = 3, p less than 0.05; cuboidal cell predominant: 596 +/- 40 ng/mg protein, n = 25, p less than 0.001). The increase in calmodulin content in Graves' disease thyroid could therefore possibly be attributed to the stimulation of the thyroid gland by the thyroid stimulating antibody. An immunofluorescence study demonstrated the presence of calmodulin immunoreactivity in the thyroid epithelial cells, particularly enriched in the apical border in the form of a granulated structure.

A study on the thyroid gland and the TSH cells in the pituitary of the ricefield eel, Monopterus albus

The thyroid gland of the ricefield eel, Monopterus albus, was located by histological studies and by radioactive iodine uptake technique in the anterior region of the head kidney and comprised follicles, which possessed à colloid-filled lumen lined by epithelial cells. The gland is not encapsulated but embedded in the haemopoietic tissue of the kidney. Treatment of the fish with ovine-TSH (NIH-TSH-S6) at a dosage of 1 USP unit for different lengths of time (12 hr to 3 days) stimulated the thyroid follicles to various degrees of response, from increase in cell height of follicular epithelium to overstimulation leading to rupture of the thyroid follicles. This treatment caused, at the same time, a marked regression in both cell size and nuclear size of the type 5 cells in the adenohypophysis, which have been identified in previous cytological and histochemical studies to be the “TSH” basophils, and accumulation of cytoplasmic granules were also observed in these type 5 cells. Fish treated with thiourea (0.15% solution) for 20 days were found to have their thyroid epithelial cells stimulated; the adenohypophyseal type 5 cells were also stimulated to increase in both cell and nuclear size with degranulation of cytoplasmic contents. The effects of thyroxine treatment (20 μg/l solution) for 20 days were exactly the opposite of the thiourea treatment in that the mean cell height of thyroid epithelium decreased and the adenohypophyseal type 5 cells regressed, accompanied by the accumulation of cytoplasmic granules. Other basophils in the adenohypophysis were also affected by these treatments but the responses were most characteristic and most obvious in the type 5 cells. In normal animals, the type 5 cells in the pituitary exhibited à seasonal cycle in activities which is probably more related to seasonal changes in general metabolism as the pattern of variation showed no sexual dimorphism. Results obtained in the present studies provided experimental verification that the type 5 adenohypophyseal cells are mainly related to the direct control of thyroid function and are hence TSH-secreting cells in Monopterus. Relationships of the type 5 cells with the thyroid and with the other basophils are also discussed.

Growth and morphological changes of thyroid intraocular grafts x-irradiated in vitro before transplantation.

SummaryThe growth, morphological structure and 131I uptake of thyroid glands irradiated in vitro with 200–1800 r and then transplanted into the anterior eye chamber of thyroidectomized rats have been investigated.The growth of irradiated grafts, in comparison with those not irradiated, is delayed one month after transplantation if grafts are irradiated with 400 r and 600 r, and after four months if they are exposed to 200 r. Doses of 1200 r and 1800 r totally inhibit growth of the grafts.With increase of radiation dose, decrease of the height of follicular epithelium, degeneration of the nuclei and cytoplasm, disappearance of boundaries between cells, desquamation of epithelium and destruction of follicles take place to an increasing extent. The intensity of lymphocyte infiltration decreases with the increase of the irradiation dose.In grafts irradiated with doses exceeding 1000 r, the capacity for uptake of 131I was decreased.

The Effect of Injected Thiouracil on Body Weight and Hatchability of the Chick Embryo

CERTAIN drugs such as sulfocyanide, thiourea and thiouracil inhibit the formation and secretion of thyroid hormone and thus are powerful goitrogenic compounds in many animals, including man.Adams and Bull (1949) injected thiourea and thiouracil into the yolk sac of developing White Plymouth Rock chick embryos. Dosages used were 0.5 ml. of a solution of 0.4 percent thiourea and 0.1 percent to 0.2 percent thiouracil on the 8th, 14th, or 18th day of incubation. The major effects of the injections were an increase in length of the incubation period, absence of retraction of the yolk sac by embryos in eggs that had been incubated for 21 to 24 days, decreased trunk and limb growth, and an enlargement of the thyroid gland with a marked increase in height of follicular epithelium and colloid depletion.Grossowicz (1946) found that chick embryos whose yolk sacs were injected with thiourea between the 7th and …