Japanese Journal of Veterinary Research;Volume 15, Number 2

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ELECTRON MICROSCOPIC OBSERVATIONS OF THE EQUINE PARATHYROID GLANDS WITH PARTICULAR REFERENCE TO THOSE OF EQUINE OSTEODYSTROPHIA FIBROSA

FUJIMOTO, Yutaka;MATSUKAWA, Kiyoshi;INUBUSHI, Hiroshi;NAKAMATSU, Masao;SATOH, Hiroshi;YAMAGIWA, Saburo

Permalink : http://hdl.handle.net/2115/1865
JaLCDOI : 10.14943/jjvr.15.2.37

Abstract

An electron microscopic study was made of equine parathyroid glands from 53 horses (12 normal horses with immature bone tissue, 31 normal horses with mature bone tissue, and 10 cases of equine osteodystrophia fibrosa), and compared with light microscopic findings. 1) By electron microscopy, the authors could identify not only chief cells (light and dark), oxyphil cells (pale and dark) and water clear cells, which were previously noted by light microscopy, but also vacuolated chief cells, transitional water clear cells and transitional oxyphil cells. 2) The chief cell is the stem cell and plays an important role in equine parathyroid glands. From the electron micrographs, the evidence may suggest that the various types of cells have been derived from the chief cell in the equine parathyroid glands. 3) The light chief cells were impressive in cases of equine osteodystrophia fibrosa. Especially in severe cases, many of the light chief cells took the form of vacuolated light chief cells (only a few vacuolated dark chief cells were seen), and in some parts of the parathyroid gland, foci of water clear cells were frequently observed. 4) The vacuolated light chief cell was regarded as an abnormal cell produced by hyperfunction, because of its richness in glycogen, marked vacuolization of the endoplasmic reticulum, vacuolization and dilatation of the Golgi vesicles and existence of lipid bodies. The water clear cell was also regarded as an abnormal inactive cell produced by hyperfunction, because of the extremely rich glycogen in the cytoplasm. The light chief cell was regarded as a functioning cell, because of the secretory granules, and dilatation of the Golgi vesicles. 5) It is suggested that secretory products may accumulate and concentrate in the vacuolar or vesicular system of the Golgi apparatus. Pro-secretory granules are formed and these may develop into secretory granules in the endoplasmic reticulum system. It is further suggested that there is some relationship between secretory granules and lipid bodies. 6) The intercellular spaces were not remarkable except in equine osteodystrophia fibrosa when they were markedly dilated or cystic and an outflow of high electron opaque substances was frequently observed in the intercellular spaces.

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