The upper right canine teeth of cats were moved distally by orthodontic devices. Examination of changes in blood supply and resorption of alveolar bone were made by LM or SEM after injection of indiaink or acrylic resin. Active rear resorption of the alveolar bone was observed on the pressure side. This rear resorption began near the orifice of perforating channel interiors. The rear resorption was always accompanied by blood vessels located at the cell free zone of the periodontal tissue pressed into the perforating channels. Resorption did not occur in the channels and no blood vessels were found there, but only in areas away from periodontal space.
These findings suggest that, for rear resorption after pressure application there is a relationship between the morphology and distribution of blood vessels and the distribution of pressure in perforating channels.

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The purpose of the present report was to study ultrastructurally the relation between aging and cell death in salivary glands. The parotid and submandibular glands of 3 to 39-month-old Mongolian gerbils were used. Four types of acinar cells, which were considered to be in the process of cell death were distinguished: (a) acinar cells having apoptosis-like chromatin condensation of the nucleus (Type I); (b) acinar cells characterized by dilated cistenae of rough-surfaced endoplasmic reticulum and chromatin condensation in the nucleus (Type II); (c) acinar cells having typical necrotic characters (Type III); and (d) acinar cells having conspicuous vacuoles and characteristic chromatin condensation in the nucleus (Type IV).
Dispersed Type I cells were observed in the parotid gland, and had a tendency to increase slightly in number after 36 months. Types II, III, and IV cells were present in groups within the acini in the parotid and submandibular glands, with a tendency to increase in number after 18 months. Moreover, some apoptotic body-like structures were observed among the acinar cells, with a tendency to increase in number after 18 months.
Acinar cells containing a TUNEL-positive nucleus were distinguished according to their distribution as follows: (1) TUNEL-positive cells, which were present singly within an acinus, were considered to correspond to the Type I cells; (2) TUNEL positive cells, which were found in a group, were regarded to correspond to either the Types II, III, or IV cells. In addition, granular TUNEL-positive reaction within cytoplasm, which may indicate the apoptotic body-like structures, was also sometimes seen.
Thus, it is suggested that, these 4 types may relate to a decrease in acinar cells in the Mongolian gerbil parotid and submandibular glands.

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Effects of mastication on the neurotransmitters of 3 major salivary glands and sialogogueinduced salivation were determined in male mice fed bulk, liquid or standard pellet diet for 2 weeks (experiment A). After experiment A, all mice were fed a standard pellet diet for further 2 weeks for restoration (experiment B).
In experiment A, compared with the standard pellet diet group only parotid gland weight was increased in the bulk diet group, but was decreased in the liquid diet group. Acetylcholine levels, only in the parotid gland were increased in the bulk diet group, but these were decreased in the liquid diet group. However, norepinephrine levels were increased only in the submandibular gland in the liquid diet group. Salivation, stimulated by pilocarpine, isoproterenol and phenylephrine was increased in the bulk diet group, whereas that stimulated by phenylephrine was decreased in the liquid diet group.
In experiment B, neither acetylcholine nor norepinephrine levels were altered in any of the groups. However, isoproterenol-and phenylephrine-induced salivation were increased in the pre-bulk diet group when compared with the standard pellet diet group.
These results indicate that short-term dietary mastication, as well as affecting parotid gland weight and salivary activity, also influences neurotransmitter levels, suggesting that changes in autonomic nerves in the salivary glands occur rapidly depending on the sensitivity of the particular gland to masticatory stimulation.

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