| Research Abstract |
The thyroid gland, Parathyroid gland, thymus, Palatine tonsil and ultimobranchial body are collectively called branchiogenous organs. Among them, the thyroid and parathyroid glands contain C cells and chief cells, respectively. These cells are specific endocrine cells, called paraneurons, and secrete calcitonin(CT) and parathormone(PTH), respectively, to be concerned with the calcium(Ca) metabolism. In the present study, the ontogeny of paraneurons in the branchiogendus organs, the influence of vitamin D(VD) administration or Ca and VD deficiency on the Ca metabolism during gestation, the influence of vitamin A(VA) deficiency on the pituitary-thyroid and pituitary- gonadal systems, and morphological changes of the pituitary endocrine cells in the aging, gestation and hibernation are examined by immunobistochemistry, morphometry and radioimmunoassay to reveal morphologically and biochemically the development and function of parangurans in the branchiogenous organs. As the results, the morphometric analysis with image-processing system revealed statistically the remarkable increase of the volume of the parathyroid gland in the Ca- and VD- deficient rats, the significant increase of the area of TSH cells of the pituitary gland in the VA- deficient rats, and the significant decrease of the area of TSH cells in the hibernating Japanese long-fingered bats. The embryological study on the development of branchiogenous organs and their paraneurons revealed by immunohistochemistry the appearance of the primordia of the thyroid gland and ultimobranchial body on day 9 of gestation, the appearance of the primordium of the parathyroid glared on day 10.25 of gestation, the fusion of the ultimobranchial body with the thyroid gland on day 12 of gestation, and the appearance of CT-immunoreactive cells in the region of the thyroid gland derived from the ultimobranchial body.
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