Comparative study of changes in activity of calcitonin-producing cells in the thyroid and lungs during hypercalcemia

Ultimobranchial and parathyroid glands of the pigeon Columba livia in response to 1,25OH2D3 administration

Columba livia were given daily intraperitoneal injections of 100 pmol of 1,25(OH)(2)D(3)/100 g body wt. for 15 days. Ultimobranchial and parathyroid glands were fixed on 1st, 3rd, 5th, 10th and 15th day of the experiment. Following 1,25(OH)(2)D(3) treatment, the plasma calcium levels of pigeon remain unchanged on day 1. The levels increase significantly after day 3 which progresses up to day 10. The plasma calcium level becomes normal at day 15. The plasma inorganic phosphate levels of Columba livia injected with 1,25(OH)(2)D(3) remain unaffected up to day 3. The levels exhibit a progressive increase from day 5 to day 10. The levels become normophosphatemic at day 15. Up to day 3 following 1,25(OH)(2)D(3) treatment, there is no change in the ultimobranchial gland of Columba livia. The gland exhibits an increased activity after 5 days 1,25(OH)(2)D(3) treatment which is evident by the increased nuclear volume and weak staining response of the cytoplasm of ultimobranchial cells. After day 10, the nuclear volume depicts a further increase and a few completely exhausted cells are discerned. Following 15-day 1,25(OH)(2)D(3) treatment the nuclear volume records an increase and degenerating cells have been observed at certain places. The parathyroid glands of 1,25(OH)(2)D(3)-treated Columba livia remain unaffected up to day 5. After day 10 and day 15, there is a progressive decrease in the nuclear volume of parathyroidal cells and reduced chromaticity of nuclei has been noticed. Moreover, after 15 days few degenerating cells are observed.

Expression of thyroglobulin and calcitonin in spontaneous thyroid gland tumors in the Han Wistar rat

Spontaneous follicular and C-cell tumors of the thyroid gland in the Han Wistar rat were examined using two morphologic procedures. Firstly, in situ hybridization (ISH) was used to localize thyroglobulin (TG) and calcitonin (CT) mRNAs. Secondly, the proteins for these markers were detected using immunohistochemistry (IHC). The aim was to study the morphology of the tumors and to examine the usefulness of TG and CT markers in the differential diagnosis of these lesions. Follicular tumors with cystic, papillary and follicular patterns showed relatively consistent expression of TG mRNA by ISH, thereby confirming the diagnostic value of this technique. However, no staining for TG markers was observed in solid lesions. In general, C-cell tumors comprised well-differentiated cells that continued to express CT mRNA and peptides even after embolic spread and metastasis. Therefore, the performance of either ISH or IHC for CT markers can be used for diagnostic confirmation. Additional features noted in C-cell tumors included the appearance of tumor emboli or metastases in association with small primary lesions (less than 5 average follicular diameters in size) and the presence of eosinophilic (amyloid-like) material showing immunopositivity for CT peptides. Finally, evidence is provided for the sequestration of TG protein by proliferating C-cells.