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In Channa punctatus the thyroid anlage is seen 40 h after hatching and is recognized as cells aggregating in the form of follicles with no colloid. During subsequent stages of development the thyroid follicles increase in number and in 5 days old larva an active division of cells and many follicles in the form of epithelial cords are seen. In 2 months old juvenile fish several thyroid follicles and lymphatic vessels are seen enclosed by connective tissue capsule. In Clarias batrachus the thyroid anlage is seen as a group of cells around tiny colloid droplets and is situated just below the bifuration of the 1st branchial artery. This stage is seen in 60 h old larva and is developed into thyroid follicles which is a long chain along the jugular vein and ventral aorta during latter stages of development. It is concluded that during early larval period of these fishes, the thyroid cells begin to trap iodine from the blood and synthesize it in the form of thyroid hormone which is stored as colloid and is also liberated in blood stream simultaneously. The compact nature of the thyroid gland in C. punctatus is because of development of connective sheath around follicles during early stages.
The distribution of pig thyroid C cells was demonstrated by a immunoperoxidase method using antiserum to porcine calcitonin. The average number of C cells per 4 mm2 counted in the deep and superficial regions was 127 and 55, respectively. The number in the cranial, middle and caudal regions was 60, 128 and 83, respectively. The number of C cells per follicular and C cells (C cell concentration) in deep and superficial regions was 4.9 and 2.6%. It was 3.2, 4.9 and 3.3% in the cranial, middle and caudal regions, respectively. These results indicate that the number and concentration of C cells were not only larger in deep than superficial regions but also in the middle region than in cranial and caudal in pig thyroid gland. These results also indicate that the C cell distribution in pig thyroid gland is the same as that of dog, human, cat, rat, guinea pig, and mouse.
Data collected from 365 calves dead from stillbirth/perinatal weak calf syndrome were analysed to determine the predictive value of thyroid gland weight as an indicator of abnormality of the thyroid gland, and to examine the relationships between abnormality of the thyroid gland and other findings in the calves and also the parity of the dam. There was a significant relationship (P < 0.001) between the thyroid gland weight and bodyweight for the calves with a histologically normal thyroid gland, but there was no such relationship for calves with an abnormal thyroid gland. Only 1.1 per cent of the histologically normal thyroid glands weighed more than 30 g, indicating that there is a very high probability that glands weighing more than 30 g are abnormal. However, 76.0 per cent of moderately to severely affected glands weighed less than 30 g. The following significant differences between calves with an abnormal and those with a normal thyroid gland were established. Abnormal thyroid glands were significantly heavier (P < 0.01), constituted a significantly greater percentage of the calf's bodyweight (P < 0.01) and had a significantly lower iodine concentration (P < 0.001). A significantly higher proportion of calves with an abnormal thyroid gland had uninflated lungs (P < 0.01), and a significantly higher proportion had pneumonia (P < 0.01). Abnormal thyroid glands were associated with a low selenium concentration in the kidneys. There were no associations between abnormalities of the thyroid gland and the parity of the dam, the presence of skeletal fractures, the weight or sex of the calf, infection with leptospira, Salmonella dublin, Bacillus species, Actinomyces pyogenes or Aspergillus species, the quantities of hepatic iron pigment, liver vitamin E concentration or serum cholesterol concentration.
BACKGROUND: Rests of thyroid tissue within the thyrothymic area are relatively common and might be of clinical importance. The purpose of this study is to define the incidence and anatomy of thyroid tissue located in the line of the thyrothymic ligament, referred to here as "rests." STUDY DESIGN: Prospective descriptive intraoperative evaluation of 100 consecutive thyroid or parathyroid procedures was undertaken to identify the incidence and anatomical location of thyrothymic thyroid rests. Photographs and histologic confirmation of the thyroid remnants were obtained. RESULTS: One hundred eighty sides of the thyroid gland are examined in 100 consecutive patients. Thyroid rests in the thyrothymic area were found in 53 patients, or on 83 separate sides of the thyroid (46%). In patients who had rests identified, 30 (57%) had bilateral rests, with 16 (30%) only on the right, and 7 (13%) only on the left. Eighty percent of identified rests were still attached to the thyroid proper by a pedicle of thyroid tissue but 20% were entirely separate. Most rests were small, with 88% being less than 1 cm in diameter. CONCLUSION: Rests of thyroid tissue within the thyrothymic area, either as entirely separate nodules or as prolongations from the thyroid lobe, are relatively common and might be of clinical importance during thyroid or parathyroid surgery.
BACKGROUND: Primary smooth muscle tumors of the thyroid gland are rare. To date, there are few cases reported of primary thyroid leiomyomas and leiomyosarcomas. METHODS: One leiomyoma and four leiomyosarcomas arising within the thyroid gland were identified in the files of the Endocrine Tumor Registry of the Armed Forces Institute of Pathology. Histologic and immunohistochemical features were reviewed and follow-up obtained. RESULTS: The patients included 2 females, ages 56 and 64 years, and 3 males, ages 45, 68, and 83 years. The patients presented with a mass in the thyroid gland that had increased in size over a number of months. All the tumors originated within a single lobe of the thyroid gland and measured from 1.1 to 9 cm in greatest dimension. Histologically, there was a fascicular pattern of growth comprised of spindle-shaped cells with blunt-ended nuclei. The leiomyoma was encapsulated, cytologically bland, and amitotic; the leiomyosarcomas were invasive with increased cellularity, pleomorphism, a high mitotic rate, necrosis, and hemorrhage. Immunohistochemical staining showed reactivity with vimentin, smooth muscle actin, muscle specific actin, and desmin. The patient with the leiomyoma was alive without evidence of disease 11 years after the initial presentation, with surgical resection as the only treatment. Three of the patients with leiomyosarcomas were dead within 2 years of diagnosis, in spite of aggressive therapeutic intervention. The remaining patient was still alive 10 months after initial presentation with multiple lung metastases. CONCLUSIONS: Smooth muscle tumors of the thyroid gland are distinctive tumors. Leiomyosarcomas can be distinguished from anaplastic carcinoma, although patient outcome is uniformly unfavorable.
The thyroid gland has an important function in almost every aspect of human physiology. As well, its location in the neck allows for easy evaluation by the dentist. Part I of this paper reviews the normal functions of the thyroid gland as well as systemic effects caused by abnormal function. This is supplemented by easily-acquired methods of physical examination of the thyroid gland suitable for the dental practitioner. Part II is a case report highlighting the potential adverse effects of dental treatment of a patient who had poorly controlled thyroid function following total thyroidectomy.
OBJECTIVE: Thyroid diseases affect women approximately 3 times more frequently than men. It has been suggested that the female sex steroids stimulate thyroid growth such as in the breast. Seventeen beta-estradiol, the major estrogen in the body acts via estrogen receptors (ER) present in the nucleus of the cell. The aim of the study is to determine the ER status in the thyroid gland tissues. METHODS: Our study was based on immunohistochemical staining for ER. Fifty previously diagnosed cases of various thyroid lesions were selected from the Surgical Pathology Records of Pathology Department, Basic Medical Sciences Institute, Jinnah Postgraduate Medical Center, Karachi, Pakistan between March and August 2000. The staining was performed on formalin-fixed paraffin embedded tissues using monoclonal anti-ER antibody (clone 1D5). Out of 50 cases, 8 were nodular goiter, 9 cases of adenoma, 19 papillary carcinoma, 10 follicular and 4 cases were of medullary carcinoma. Surrounding normal tissue was available in 25 (50%) cases, 4 non-neoplastic and 21 neoplastic lesions. Out of 50 cases, 10 (20%) were males and 40 (80%) were females, the youngest patient was a 14-year-old female and the eldest patient was a 56-year-old male. RESULTS: Despite the availability of normal thyroid tissue and a wide range of lesions, none of our cases showed positive staining. CONCLUSION: In contrary to many earlier reports by immunohistochemical method using monoclonal antibody (clone 1D5) on formalin-fixed paraffin-embedded thyroid tissues, the ER are not detectable. The effect of estrogen on thyroid gland may be indirect one.
Human thyroid gland was investigated in 6 embryos at stage 23. In 4 embryos, in the peripheral part of the thyroid gland, distinct follicles were observed. Some of them were filled with PAS positive substance.
Indirect lymphography of the thyroid gland was performed in 144 patients. A conclusion was drawn that the use of superfluid oil contrast preparations of lipidol, miodyl type etc. in indirect lymphography of the thyroid gland will permit to obtain the exhaustive information on the state of the endocrine organ and regional lymph nodes. Lymphography with the aid of oil contrast preparation iodolipol diluted with ether and heated to the body temperature is less informative; water-soluble contrast agents were less effective. All the test contrast agents proved to be ineffective for detection of changes in the lymph nodes. Use of iodolipol for lymphography of the thyroid gland without preliminary mixture with ether is not recommended.
3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), a chlorine disinfection by-product in drinking water, causes follicular adenomas and carcinomas in thyroid glands of Wistar rats with an unknown mechanism. We evaluated effects of MX on blood thyroid stimulating hormone (TSH), thyroxine (T(4)), triiodothyronine (T(3)), prolactin (PRL) and growth hormone (GH) levels in male and female Wistar rats to assess their role in the tumorigenesis. The levels of TSH, PRL and GH in serum of male rats were not significantly affected by a single dose of 1, 10 or 60 mg/kg of MX administered by gavage 2 h before sampling. In repeated dose experiments MX was administered at dose levels of 1, 10 or 60 mg/kg of MX (40 mg/kg for females) in water by gavage daily for 1 or 3 weeks. Thyroid glands, adrenal glands and the liver were evaluated for morphological changes and cell proliferation activity after staining with proliferating cell nuclear antigen (PCNA). The dose of 60 mg/kg MX was toxic upon repeated administration. Nevertheless, MX did not affect blood TSH and T(4) levels at any time point in either sex. T(3) concentration increased transiently in males (by 37% after week 1) at the highest MX dose but not in females. MX did not change the weights of thyroid glands, their morphology and cell proliferation activity by the end of the week 3. MX did not affect blood PRL levels but decreased GH levels in males at all doses after the first week of MX treatment. The results indicate that MX does not alter blood TSH and thyroid hormone levels in rats, and imply that MX may not cause thyroid follicular cell tumors by TSH-mediated hormonal promotion.
OBJECTIVE: Changes in the functional state of beta cells by neonatal stimulation or adolescent suppression have reduced the incidence of type 1 diabetes mellitus in animal models. The aim of this study was to evaluate the effect of manipulation of the activity of the thyroid gland by neonatal stimulation or by adolescent suppression on the prevalence of spontaneous autoimmune thyroiditis (AIT) in rats. METHODS: Bio-Breeding/Worcester (BB) rats were treated neonatally with sodium iodine (NaI) or thyroid stimulating hormone (TSH), or during adolescence by triiodothyronine (T(3)), and the lymphocytic infiltration in the thyroid gland was evaluated. RESULTS: Neonatal treatment with NaI decreased the prevalence of AIT to 32+/-9% compared with 66+/-5% in the controls (P<0.002), mainly caused by a reduction among the female rats (13+/-9% vs 52+/-8%, P<0.006). TSH had no effect. Post neonatal suppression of the thyroid gland by T(3) had a biphasic response. Early in adolescence the overall prevalence was 14+/-7% compared with 66+/-5% in the controls (P<10(-5)); for female rats AIT was prevented (0+/-0%) compared with 52+/-8% in the controls (P<0.0003) and in male rats the values were 29+/-13% compared with 80+/-6% in the controls (P<0.001). Treatment with T(3) later in adolescence increased the overall prevalence to 81+/-7% compared with 66+/-5% in the controls (not significant). For female rats the prevalence increased to 78+/-9% compared with 52+/-8% in the controls (P=0.04). The degree of thyroiditis among the affected animals was similar in all groups. CONCLUSION: Neonatal stimulation of the thyroid gland by iodine or early adolescent suppression by T(3) reduced the prevalence of AIT whereas T(3) given later increased the prevalence of thyroiditis in rats. Thyroid activity at various ages seems to be of importance for the development of autoimmune thyroiditis.
OBJECTIVE: To find out thyroid volume and its functional status in women in reproductive age as well as possible correlation between thyroid size and functional status and age and residential location of women. DESIGN: Project can be characterized as an epidemiological study and consists of three separate observations. SETTING: 1st Internal Clinic, UPJS, Kosice, Medical Faculty, Slovakia. METHODS: 347 women from different regions of Eastern Slovakia (160 aged 20-29 and 187 aged 30-40) were measured thyroid volume via ultrasonography and thyroid functional status by RIA TSH and anti TPO examinations. Urinary iodine was examined in 70 cases. In this part of the study correlation between thyroid size and functional status and age and residential location of women were determined. Four days after delivery thyroid volume in 99 women was measured. The volume was correlated with the number of previous pregnancies. Thyroid volume was correlated with residential location and number of pregnancies of 77 women that had not delivered in the previous year. RESULTS: Women aged 20-29 years had thyroid volume smaller than women aged 30-40 (8.78 ml/10.66 ml; p < 0.01). The size of thyroid gland was not only affected by age but also by residential location. The largest thyroid glands and increased level of anti TPO antibodies in both age groups were found in women from agricultural regions and regions close to chemical factory. The women with anti TPO antibodies had increased level of TSH as well as more frequently changed echogenity of thyroid gland. Median of urinary iodine was 13.2 micrograms/dl in both age groups and indicated sufficient iodine intake in the observed area. The volume of thyroid gland four days after delivery did not exceed 22 ml in 89.9% of cases. Significant difference in size of thyroid gland depending on number of previous deliveries was not only observed in women 4 days after delivery but also in those that had not delivered during previous year. The largest volumes were measured in secundiparous mothers. CONCLUSION: Polluted environment affects the size and functional status of thyroid gland. Environment can via this negative impact on thyroid gland influence fertility, pregnancy and fetus development in women in reproductive age.
Thyroid glands of 7 to 21 day-old chick embryos were examined by electron microscopy using freeze-fracture and thin-section preparations. The primitive follicle lumen first appears between two adjacent epithelial cells in 8 day-old embryos, and is formed in the region of a focal tight junction (macula occludens). The focal tight junction develops into the zonula occludens when the primitive follicle lumen first forms. The zonula occludens is, at first, composed of 4.6 +/- 2.45 strands, but with increasing embryonic age the number of strands increases to 5.9 +/- 1.41 in 13 day-old, and 8.0 +/- 1.75 in 19 day-old embryos. Thyroglobulin stored within the embryonic gland lumina is isolated from the mesenchymal tissue even at the first appearance of these follicle cavities. Well developed gap junctions already occur in the thyroid gland of the 7 day-old embryo, so that an intimate relationship and communication between these cells already exists at the time of their functional differentiation.
We estimated the size of the thyroid gland by palpation and measured thyroid gland volume with ultrasound in the immediate postpartum period and six months after delivery in 16 women. The 13% reduction in the mean thyroid gland volume detected six months after delivery implied that the thyroid gland enlarges slightly during pregnancy. Physical examination, however, did not detect any goiters during the immediate postpartum period and did not identify a change in thyroid gland size six months after delivery. The thyroid gland enlargement that occurs during pregnancy is not large enough to be detected by physical examination. We urge physicians to discard the commonly held notion that goiter frequently develops during pregnancy.
An attempt was made to explain the bone-preserving effect of estrogen by analysis of estrogen receptors (OER) in the calcitonin-producing C-cells of the human thyroid gland. Thyroid tissue from twenty patients with benign hyperthyroidism and three patients with medullary thyroid carcinoma was used. The C-cells were identified immunohistochemically using a polyclonal antibody to calcitonin, and by a similar staining technique the adjacent sections were stained for the OER protein using a monoclonal antibody (H 222-ABBOTT, USA). In spite of an intense nuclear staining of the positive control tissue (an OER positive breast carcinoma) no specific OER-staining was identified in C-cells or any other cells of the thyroid gland. Neither a dextran-coated charcoal assay nor a solid-phase immunoenzyme assay revealed any quantitative OER activity in tissue homogenates. Various observations point to a regulating mechanism between calcitonin and estrogen. The nature of this mechanism is not known, but according to our study it is unlikely to be a direct one.
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Angiogenesis entails the sprouting of new vessels from pre-existing vasculature. In adults, angiogenesis occurs in the thyroid gland during disease processes such as hyperplastic goiter, Graves disease, thyroiditis, and cancer. In the present study multiple morphologic characteristics of microvessels were measured in and compared between 18 cases of Graves disease, 29 cases of Hashimoto's thyroiditis, and 15 control cases. All histologic sections were immunostained for CD31. Quantification of microvessel density (MVD), major axis length, minor axis length, area, perimeter and shape factor was performed by image analysis. MVD was increased significantly in both forms of autoimmune thyroid disease. Significantly higher values were found in Graves disease in comparison to Hashimoto's thyroiditis. In contrast, major axis length, minor axis length, and area had significantly higher values in Hashimoto's thyroiditis than in Graves disease. The statistical analysis revealed MVD as the unique significant morphometric factor discriminating the two autoimmune entities.