1957 年 24 巻 4 号 p. 303-320
Aqueous solution of NaF, containing 10 to 250 ppm of fluorine was given per os daily to premature rats, which were sacrificed on the 3 rd to 55 th day after the begining of its administration. Macroscopically striation or lack of pigmentation and attrition of the incisor were observed. Microscopic observations were carried out especially on the enamel epithelium. On NaF-intoxication ameloblasts in the stage of matrix formation show in their cytoplasms SH positive substances like enamel matrix, and severe NaF-intoxication leads to a few cyst formation between the layers of ameloblasts and enamel matrix. The cells of the wall of large cyst were reduced in the activities of their alkaline and acid glycerophosphatase and alkaline adenosine triphosphatase together with loss of sudanophilic, acidophilic substance in the infranuclear portion of ameloblasts. Another portions of the enamel epithelium showed no remarkable decrease in an alkaline phosphatase activity. However, acid phosphatase in the stratum intermedium was occasionally reduced in its activity.
In maturation stage several changes of the enamel epithelium were noted; vacuolar degeneration, reduction of Fe-positive granules, presence of coarse Fe-positive granules, occasionally disappearance or nodular proliferation of ameloblasts containing remarkable Fepositive substances.
In long-term intoxication rats were given per os daily aqueous solution of NaF, containing 10 and 50 ppm of fluorine, for the period of 280 days. Macroscopically striation or lack of pigmentation were visible on the incisor of 50 ppmF group rats. But no sigificant change was histologically observed on the enamel organs of all these groups.
Another rats weighing 150-250 g each were operatively extirpated their unilateral salivary glands (parotid, submaxillary and sublingual glands) after 24-hours of fasting, then the rats received intravenous injection of 0.5-2.0 per cent fluoride solution (0.2-0.5cc of aqueous NaF and NaF·HF) . After various intervals, 7 to 60 minutes, the salivary glands of the opposite side were extirpated and histologically investigated. The following changes were observed; increase in the number of secretory granules in the striated tubules, discharge of granules, homogenous secretion in the lumen, irregularity of shape of secretory granules, coarse granules accumulated in the supranuclear portion, diminishing and/or disappearing in number of granules, and striated cells losing their cylindrical shape and elevating the cells from the basal membrane.
A profuse salivation occurred soon after intravenous injection of a toxic dosis of fluoride solution. From the histological finding it may be due to hyperf unction of the sub-maxillary gland. Furthermore, it is noteworthy that the striated tubules show a degenera-tive change.
No remarkable histologic change of the salivary gland was observed on the chronic fluorosis of the rat as given 10 or 50 ppm of fluorine per os daily during 280 days.