Thyroid ultrastructure

A COMPARATIVE STUDY ON THE MOUSE THYROID ULTRASTRUCTURE AFTER STIMULATION WITH TSH AND LATS. 

Holm R, Farrants GW, Nesland JM, et al. Ultrastructural and electron immunohistochemical features of medullary thyroid carcinoma. Virchows Arch. A Pathol. Anat. Histopathol. 1989 414 375-384. 

Singh A, Bhatnagar MK, Villeneuve DC, et al. 1985. Ultrastructure of the thyroid glands of rats fed photomirex A 48-week recovery study. J Environ Pathol Toxicol Oncol 6(1) 115-126. 

Thyroid toxicity (decreased thyroxine levels and ultrastructural changes) was observed after rats were fed 2,000 mg/kg/day of di- -octylphthalate in the diet for 3, 10, or 21 days (Hinton et al. 1986). 

Pitsiavas V, Semerdely P, Li M, Boyages SC (1997) Amiodarone induces a different pattern of ultrastructural change in the thyroid to iodine excess alone in both BBAV rat and the Wislar rat. Eur J Endocrinol 137 89-98... 

Rat (Wistar) 3d (F> Endocr 2000 (decreased serum T4 ultrastructural changes consistent with thyroid hyperactivity) Hinton et al. 1986... 

M (altered thyroid follicular ultrastructure, increased serum T3 hormone)... 

Collins et al. (1977) conducted one of the more comprehensive evaluations of the histopathology of intermediate-duration exposures to Aroclor 1254 in rats. Rats were fed 5, 50, or 500 ppm Aroclor 1254 in food for 4 weeks (approximately 0.44,4.4, or 44 mg/kg/day). Ultrastructural changes in the thyroid were evident at the lowest exposure level and became more pronounced and evident with light microscopy at the 50 ppm exposure level (4.4 mg/kg/day). Serum concentrations of TT4 were significantly depressed (42%) at the 50 ppm level and both TT4 and TT3 were depressed (79 and 13%, respectively) at the 500 ppm level. Thyroid lesions in rats that were exposed to 500 ppm for 6 weeks followed by 250 ppm for 6 weeks were largely absent after a subsequent 12 weeks on a control diet, suggesting substantial recovery, and were not evident at all after a period of 35 weeks on the control diet (Collins and Capen 1980a). A similar time course of recovery of serum TT4 concentrations was observed. Thus, the observed lesions in this study and at these doses appeared to be reversible. 

Collins WT, Capen CC. 1980a. Ultrastructural and functional alterations of the rat thyroid gland produced by polychlorinated biphenyls compared with iodide excess and deficiency, and thyrotropin and thyroxine administration. Virchow Arch B Cell Pathol 33 213-231. 

Collins WT, Capen CC, Kasza L, et al. 1977. Effect of polychlorinated biphenyl (PCB) on the thyroid gland of rats Ultrastructural and biochemical investigations. Am J Pathol 89 119-136. 

Amiodarone induces specific ultrastructural changes of the thyroid gland in rats, including marked distortion... 

Pappa A, Jackson P, Stone J, Munro P, Fells P, Pennock C, Lightman S. An ultrastructural and systemic analysis of glycosaminoglycans in thyroid-associated ophthalmopathy. Eye 1998 12 237-244. 

Zeligs. J. D., and Wollman, S. H. (1979). Mitosis in rat thyroid epithelial cells in vivo I. Ultrastructural changes in cytoplasmic organelles during the mitotic cycle. J. Ultrastruct. Res. 66,53-77. 

We need more information on the structure and ultrastructure of the thyroid in the two types of cretinism. We need to know whether there are specific aspects of thyroid morphology in hypothyroid newborns and stillbirths in endemic areas. We also need to know whether there are age-related changes in the thyroid of hypothyroid infants and children. In other words, how valid is the hypothesis that only progressive atrophy of the thyroid will result in permanent hypothyroidism and myxedematous cretinism in some individuals while the development of compensatory thyroid hyperplasia explains the transient character of hypothyroidism in others (5). Finally, is there any morphological evidence of an autoimmune process within the thyroid ... 

Fig. 6 Mouse thyroid gland 10 min. after LATS injection. The ultrastructural aspect of the follicular cells does not differ from that of control animals, x 16. 000.

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