methylthiouracil and Carcinoma--Papillary

Papillary carcinomas of the thyroid gland induced in rats by combined methylthiouracil (MTU)/nitrosomethylurea treatment were studied electron microscopically and histochemically for their acid phosphatase activity, radioactive iodine uptake and for their thyroglobulin synthesis. The papillary carcinomas accumulated radioactive iodine, synthesized thyroglobulin and showed a perinuclear localization of acid phosphatase activity in the cytoplasm. After omitting the reactive thyrotropic effect (cessation of MTU administration) a decrease of both iodine organification and acid phosphatase activity was observed. The synthesis of thyroglobulin was also reduced. The changes in the ultrastructure of tumour cells corresponded to the respective functional activities. The results suggest that the papillary carcinomas may have a functional dependence on thyroid-stimulating hormone.

Topics: Acid Phosphatase; Animals; Autoradiography; Carcinoma, Papillary; Female; Iodine Radioisotopes; Methylnitrosourea; Methylthiouracil; Microscopy, Electron; Rats; Rats, Inbred Strains; Thyroglobulin; Thyroid Neoplasms

Irradiation of the neck region of 10 days old Wistar rats with 300 rads X-rays and their subsequent treatment with MTU leads to the development of thyroid tumors. The ultrastructure of the thyroid tumors induced was studied by transmission (TEM) and scanning electron microscopy (SEM). In follicular carcinomas, cylindrical or high columnar cells with abundant microvilli, well-developed ergastoplasmic reticulum and a hypertrophied Golgi complex predominate. The cytoplasm of the tumor cells of papillary carcinomas was composed of large pleomorphic cisternae, irregular in shape mitochondria, dense bodies, phagolysosomes and lamellar or multivesicular structures. Scanning electron microscopy revealed in the control animals a regular pattern of thyroid follicles tied to each other by tissue bridges and covered by set of blood and lymph vessels. The relief of the follicular carcinomas was irregular indicating follicles different in size and shape. The internal surface of the neoplastic follicles was also irregular as result of deep invaginations and intrafollicular cell growth. The apical region of the normal and neoplastic thyroid follicular cells was covered with abundant microvilli protruding into the colloid.

Topics: Adenocarcinoma; Animals; Carcinoma, Papillary; Male; Methylthiouracil; Microscopy, Electron; Microscopy, Electron, Scanning; Neoplasms, Experimental; Neoplasms, Radiation-Induced; Rats; Thyroid Neoplasms

Nuclear DNA content was measured in 3 normal, 9 hyperplastic and 16 neoplastic rat thyroid glands. Thyroid hyperplasia and tumor growth were induced after treatment of the animals with X-rays and methylthiouracil. In the control animals only diploid thyroid epithelial cells were observed. At the stages of diffuse and nodular thyroid hyperplasia, the total DNA content per nucleus indicated for a diploid chromosome number and only a few cells were hyperdiploid. In the thyroid adenomas and carcinomas a scattering of the diploid region and an increase in the number of hyperdiploid cells was found. Among the various types of thyroid tumors neither difference in the number of hyperdiploid cells, nor typical pattern of distribution of these cells in the histogram was found. The increased number of hyperdiploid cells in the hyperplastic and neoplastic thyroids suggest an increase in the proportion of the cells entering the cell cycle and does not indicate for appearance of a neoplastic stemline.

Topics: Adenocarcinoma; Adenoma; Animals; Carcinoma, Papillary; Cell Nucleus; Cystadenoma; DNA; DNA, Neoplasm; Epithelium; Hyperplasia; Male; Methylthiouracil; Neoplasms, Experimental; Neoplasms, Radiation-Induced; Rats; Thyroid Gland; Thyroid Neoplasms

Topics: Animals; Carcinoma; Carcinoma, Papillary; Cell Nucleus; Cell Transformation, Neoplastic; Chromatin; DNA; Epithelial Cells; Epithelium; Hyperplasia; Male; Methylthiouracil; Microscopy, Phase-Contrast; Rats; Spectrophotometry; Staining and Labeling; Thyroid Neoplasms; Time Factors

Topics: Adenocarcinoma; Administration, Oral; Animals; Carcinoma; Carcinoma, Papillary; Injections, Intravenous; Methylthiouracil; Neoplasms, Experimental; Nitrosourea Compounds; Rats; Thyroid Neoplasms; Time Factors

Topics: Adenoma; Animals; Carcinoma; Carcinoma, Papillary; Cricetinae; Endoplasmic Reticulum; Golgi Apparatus; Methylthiouracil; Microscopy, Electron; Neoplasms, Experimental; Organoids; Thyroid Gland; Thyroid Neoplasms