Immunohistochemical localization of thyroid hormone in rat thyroid gland.

Direct and indirect immunofluorescence techniques were used to localize the thyroid hormones triidothyronine (T3) and thyroxine (T4) in adult rat thyroid gland. Optimum dilutions of the antisera were established and four tissue fixatives were investigated for usefulness in this technique. Use of antibodies specific for either T3 or T4 resulted in brilliant fluorescence in the colloid pools and apical cytoplasm of follicular cells. In all cases, the adjacent parathyroid gland was devoid of fluorescence. This report demonstrates that these dipeptide hormones can be localized by using immunofluorescence techniques.     

D-asparatate oxidase in the thyroid gland.

D-Aspartate oxidase was isolated from the pig thyroid gland and purified over 600 times. The enzyme was obtained in an inactive form of apoenzyme and was activated by FAD. It was specific towards the D-form of aspartic acid, had no effect on the L-form, and was also inactive towards other monocarboxlyic D-amino acids. The enzyme was only slightly active towards D-glutamate. The Michaelis constant based on the Lineaweaver-Burk plot was 5 mmol/l. The optimum pH was 8.7. D-Aspartate oxidase was inhibited by KCN in concentrations varying from 0.05 to 1 mmol/l. The biological role of this enzyme in the thyroid gland is discussed.     

Studies on quantitative morphology. XII. Distribution of thyroid gland compartments in an activated rabbit thyroid gland

A series of longitudinally cut step sections with a distance of 50 microns of a rabbit thyroid gland was measured by point counting for the relative tissue elements colloid, epithelium, and interstitium. Furthermore, the ratio epithelium:colloid was computed, which was somewhat high, indicating an activated stage. Higher colloid data were found in the outer regions and insignificantly lower epithelium values. Neither the volume data nor the distribution of the structure elements show any difference between both of the lobes. The degree of heterogeneity was comparably low, but only about 30% of all data for the relative colloid percentages or for the ratios are enclosed in a range of +/- 5% in relation to the most accurate value from all hits all over the gland, and about 20% of the ratio data are crossing the +/- 20% borderlines. It was calculated that measuring of not more than 5 sections with approximately equal distances with a very few 10(3) hits yields values of an acceptable accuracy for all parameters and this with a reasonable time expense.     

Sex dimorphism in the thyroid gland. IV. Cytologic aspects of sex dimorphism in the rat thyroid gland

This study was designed to explain whether the sex-dependent differences in the structure of the thyroid gland of adult male and female rats depend on quantitative or qualitative changes in the thyroid follicular cells. Absolute thyroid gland weight was similar in male and female rats, but its relative weight was markedly higher in females however. Volume fractions of epithelium and stroma were higher and that of colloid lower in male than in female rats and the epithelium/colloid ratio was higher in the males. Also absolute the volumes (in mm3) of epithelium and stroma were higher in the males; the thyroid gland of females contained more colloid. The average volume of a thyroid follicular cell, estimated by stereology, was higher in males than in females, although the thyroid gland contained similar numbers of follicular cells in both sexes. Also, thyroid glands from both male and female rats contained a similar DNA quantity. Results of the present study show that the sex dimorphism in the rat thyroid depends upon a difference in the mean volume of thyroid follicular cells, with males having larger cells than females. However, in both sexes the thyroid gland contains a similar quantity of these cells.     

Selenium concentrations in the human thyroid gland.

Recently, we found that prediagnostic serum selenium concentration was significantly lower for cases developing thyroid cancer (n = 43) than for controls. We assumed that redistribution of serum selenium into the affected tissue took place in the prediagnostic period. The present study was carried out to determine the physiological concentration of selenium in the thyroid, since very few data are available in the literature. The concentrations of selenium in the thyroid (n = 45) and liver samples from Norwegians who had died because of acute illness or accidents were determined by hydride generation atomic absorption spectrometry. The mean selenium concentration was found to be 0.72 +/- 0.44 microgram/g in the thyroid and 0.45 +/- 0.11 microgram/g in the liver tissue. The surprisingly high concentration of selenium in apparently normal thyroids indicates that selenium has important functions in this organ. The remarkably broad range, together with the observation that no significant correlation exists between thyroid and liver concentrations, suggest that factors other than the selenium status are important determinants for the selenium concentration in the thyroid gland. This observation is consistent with our hypothesis that in carcinogenesis, prediagnostic processes influence the serum-/thyroid-ratio of selenium.     

REVIEW. Melatonin and the thyroid gland

This review briefly summarizes the published data on relationships observed between melatonin - the main pineal hormone, and the thyroid gland. The prevailing part of the survey is devoted to thyroid growth processes and function. A large experimental evidence exists suggesting the inhibitory action of melatonin on thyroid growth and function; this effect has been revealed by using different experimental models: by chronic and short-term melatonin administration in vivo, by light restriction, which is known to increase the activity of the pineal gland, by pinealectomy, etc., as well as by employing the in vitro conditions. Thus, much information has been accumulated, indicating - in experimental conditions - a mutual relationship between the pineal gland and the thyroid. The confirmation of these relations in clinical studies in humans meets numerous difficulties, resulting - among others - from the fact that, nowadays, human beings, as well as certain animal species, used in experimental studies, have been living far away from their natural and original habitat. It makes almost impossible to compare the results obtained in particular studies performed in different species, on the pineal-thyroid interrelationship.     

Metabolism of D-mannosamine in bovine thyroid gland slices.

1. The nature of the acid-soluble mannosamine intermediates was investigated in bovine thyroid gland slices after incubation with a tracer amount of [14C]mannosamine plus 10 mM carrier mannosamine. 2. These radioactive intermediates were separated by ion exchange, columns, characterized by paper chromatography and were identified as N-acetylmannosamine-6-P. The radioactivity associated with these acid-soluble compounds constituted about 17 percent of the added [14C]mannosamine. 3. [14C]Mannosamine was incorporated as sialic acid only into thyroglobulin.     

Amylase in the thyroid gland

Summary Amylase activity detected in thyroid extracts was significantly higher than that of normal sera. A starch film technique revealed the existence of amylase activity in the follicular lumen and on the follicular epithelia. By electrophoretic analysis of thyroid extracts, 4 bands of amylase activity were observed, one being of the same mobility as parotid and the other 3 more anodic. Amylase extracted from the thyroid appeared in the same position as pancreatic or parotid amylase on Sephadex G75 gel filtration. The possibility is discussed that the thyroid may synthesize amylase of salivary type, which is secreted from the follicular epithelia into the follicular lumen, where it may be transformed into anionic forms.     

Amylase in the thyroid gland

Amylase activity detected in thyroid extracts was significantly higher than that of normal sera. A starch film technique revealed the existence of amylase activity in the follicular lumen and on the follicular epithelia. By electrophoretic analysis of thyroid extracts, 4 bands of amylase activity were observed, one being of the same mobility as parotid and the other 3 more anodic. Amylase extracted from the thyroid appeared in the same position as pancreatic or parotid amylase on Sephadex G75 gel filtration. The possibility is discussed that the thyroid may synthesize amylase of salivary type, which is secreted from the follicular epithelia into the follicular lumen, where it may be transformed into anionic forms.     

Sex dimorphism in the thyroid gland. I. Morphometric studies on the thyroid gland of intact adult male and female rats

Morphometric studies were performed on thyroid glands of intact adult male and female rats. Thyroid follicular cells are markedly higher in the male rats than in the females during estrus. The volume fraction of the epithelium is larger but the fraction of colloid is less in males than in females. Also epithelium/colloid ratio is higher in male than in female rats.     

Localization of thyroid peroxidase and the site of iodination in rat thyroid gland.

The iodinated protein was localized in thyroid tissue slices by using radioautography. In unfixed tissue, the labelled protein was localized in the colloid, whereas, in tissue that was fixed before the 125I addition, the label was within the follicular cell. This localizes thyroid peroxidase largely on the endoplasmic reticulum of the cell.