Muscle fibers of the masseter muscle of mice which had been fed a fine-grained diet for various periods were studied histochemically and morphometrically. The diameters of both extrafusal and intrafusal muscle fibers decreased with time in mice fed a fine-grained diet, compared with those of control mice. In animals maintained on the special diet for 160 days after weaning at the 20th postnatal day, the effects of the diet on the diameter of muscle spindles were severe, and the diameter of each type of red and white fibers was significantly smaller than those of control animals. But a significant difference was not recognized in the diameter of intermediate fibers between control and treated mice. Unexpectedly, white fibers having a smaller diameter than red fibers were observed in diet-fed mice after the 180th postnatal day, although white fibers having such small diameter were not detectable in control animals. Succinic dehydrogenase activities were decreased in both extrafusal and intrafusal fibers of experimental animals. Moreover, muscle spindles with no annulospiral endings were increased in number in mice fed the diet for 130 and 160 days after weaning, although those spindles also increased in control animals. The diameters of outer capsules and primary endings were also significantly decreased in the animals kept on the diet for a long time. These effects of the finegrained diet on the mouse masseter muscle became severer with time.
The formation of the anulospiral ending of la fibers in muscle spindles was investigated in the masseter muscle of developing mice. Before 15 days after birth, the complete anulospiral ending was not observed in almost all of the muscle spindles examined. With the growth of mice, the la fiber began to construct the spiral ending, and by the 40th postnatal day after weaning, almost all of the la fibers of the muscle spindles had complete coiled endings, though the formation still continued in some spindles. The continuous formation of anulospiral endings for a long period after weaning indicates that muscle spindle morphogenesis may be affected by muscle tension in the masseter muscle due to the movement activated after weaning.
The aim of the present study was to assess the application of monoclonal antibodies to the detection of black-pigmented Bacteroides spp. in subgingival plaques by immunoslot blot assay. Subgingival plaque samples from adult periodontal patients were examined by immunoslot blot assay with monoclonal antibodies that specifically recognize Bacteroides gingivalis, Bacteroides intermedius serogroups I and II, and Bacteroides melaninogenicus. The assay can detect specifically these Bacteroides spp. in the subgingival plaques. Therefore, we investigated the distribution of these Bacteroides spp. in the subgingival plaques of patients classified by Russell's periodontal index. Reactivities of their plaques with monoclonal antibodies toward B. gingivalis and B. intermedius serogroup I were clearly related to the severity of the periodontal disease, but this was not the case with B. intermedius serogroup II and B. melaninogenicus. These results indicate that this immunoslot blot assay using monoclonal antibodies toward these Bacteroides spp. provides simple detection and monitoring of these organisms in periodontal patients.
The effects of easily chewable diets and unilateral extraction of upper molars on the masseter muscle were studied in developing mice. A liquid diet requiring no mastication suppressed the development of the masseter muscles more than a fine-grained diet, and extraction of unilateral upper molars also caused inhibition of muscle development. Moreover both unilateral extraction of upper molars and a liquid diet had an additive effect on the the suppression of the postnatal development of the masseter muscle and bilateral suppression of the development of the masseter muscle was induced following unilateral extraction of upper molars. These findings suggest that the sensory input from the sensory endings in the periodontal ligament may also play an important role in the postnatal development of the masseter muscle and that there may be some crossing pathways to convey the sensory input coming from the side of the extracted upper molars to the contralateral motor neurons via the interneuronal circuits.
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