ラット唾液腺の加齢的変化に関する組織学的研究

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A longitudinal study was carried out on the growth and age change in the histology of the parotid gland, submaxillary and sublingual glands of rats starting from the day of animal's birth toward as longest as 1083 postnatal days. Results obtained were summarized as follows. 1. Of the salivary glands studied just after birth of rats, the sublingual gland showed pictures of earliest development, followed in order by submaxillary and then by parotid glands. 2. The acini of the sublingual gland showed some close resemblance to those of the mature organ as early as at birth. With regard to the duct system of gland, however, development and differentiation of its component cell groups was not completed until about 5 days after birth. 3. The submaxillary gland at birth of rats did not show any appreciable differentiation except that the terminal portion could be distinguished from the duct system. The cell groups constituting not yet differentiated acini of the terminal portion were made up of two varieties, the dark cells and light cells, of which the former occurred predominantly. With progressive days, however, these cells of dark variety began to disappear and were transformed into cells of light variety, and by the age of 35 to 40 days of animals the entire cells were of light variety and became bigger in size of cell body, finally forming the mature acinus. Differentiation of the striated duct portion had been completed by the age of 25 to 30 days and differentiation of other parts of gland except the granular portion was completed by the age of 40 days. This particular portion which is characteristic of the submaxillary gland made its first appearance by 40 to 50 days after birth of rats and its rapid differentiation took place only after 60 days of age so that full growth of the submaxillary gland should be expected later than 90 days after birth. 4. The parotid gland at birth of rats did not show even its characteristic lobular structure, nor was it easy to distinguish between the terminal portion and duct. However, its postnatal growth was so rapid that by only 3 postnatal days the terminal portion and duct became distinguished. As in the case of the submaxillary gland, the terminal acini in the parotid gland showed the presence of dark cells in early stage of growth which later on transformed into the light cells, and by about 20 days of age differentiation of the gland was complete. In about the same age stage, the striated portion of the duct system became completely differentiated and already showed some resemblance to the mature parotid gland. 5. When maturity is reached with each gland, they in turn suffer age change beginning at different age stages. The parotid gland was the first to suffer age change beginning past 180 days of life and the change was noted most conspicuously. The age change in the submaxillary gland occurred past 360 days of life, and hardly any appreciable age change was noted with the sublingual gland even in old age. It was observed that the progressive change of these organs was not necessarily the function of life span of animal, but apparently affected considerably by individual difference. 6. Of major changes of the salivary glands by aging, there occurred in the terminal acini atrophy and vacuolar degeneration of cells in the first place, accompanied by even more conspicuous irregularity in size of nuclei that resulted from pycnosis and enlargement. In the duct system, there occurred dilatation in the whole system, and in some part proliferation of epithelial cells was observed. Fibrous proliferation and some times hyaline or mucous degeneration were observed in the interlobular connective tissues. Another characteristic sign of age change in the salivary glands is the occurrence of oncocytes. 7. The oncocytes in the most cases appeared in the epithelial layer of duct and sometimes in the acinous part. In the submaxillary gland on the other hand, these cells were most frequently seen in the granular portion of duct. 8. Mast cell infiltration could be noted to occur by 8 days after birth with the submaxillary and sublingual glands and by 60 days after birth with the parotid gland. With advancing age of animals, number of these cells and the extent of their distribution progressively increased.
九州歯科学会の論文
1975-01-31

著者

江口正昭
九州歯科大学口腔病理学教室

ラット唾液腺の加齢的変化に関する組織学的研究

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