Muscle spindles are one of the most popular sensory receptors found in skeletal muscles and their physiological function has long been studied using various muscles. Recent advances in the method recording from spindle afferents in intact animals facilitate understanding of the singnificance of this kind of receptors for motor control. Chronic experiments on spindle behaviour of the masticatory muscles reveal that secondary spindle endings can transmit information on the jaw position while primary spindle activities are more related to the velocity of jaw movement than to the jaw position though their firing patterns are more complex in intact animals than in anesthetized ones. These spindle behaviour seems to be controlled by the co-activation mechanism of alpha and gammamotoneurons, although both activities are not rigidly related with each other. In addition to facilitation of alpha-motoneuron activities during jaw closing phase of a rhythic jaw movement cycle, spindle discharges contribute to stabilize jaw position through the jaw-jerk reflex path.

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It has been long known that the tooth characters and the form of tooth-bearing bones in the mouth are valuable as a taxonomic character in Salmonidae. This paper is a report on the development and growth of dentition in the mouth during larval and juvenile stages in the char, Salvelinus pluvius.
The first indication of conical teeth on the pre-maxillary, maxillary and dentary was observed in about 15mm in standard length (SL), 10 day old, on glossohyal when the fish became about 18mm SL, 20 day old, on palatine about 19mm SL, 30 day old, and on vomer about 23mm SL, 70 day old. These fish grew at a rate of 0.14mm per day up to 40th day of development, but between the 40th and 100th day, growth slowed to 0.03mm per day. During this period, the total number of teeth and the individual tooth length increased with age. And, the fully developed dentition was found in the mouth of specimens exceeding 53mm SL, 150 day old. The length of teeth increased with age during young and adult stages. The percentages of functional teeth number to total number of teeth on the dentary and maxillary in 18-25mm SL char, 90 and 100 day old, were the highest in all of the 16 age groups, from 10 day old to 3⁺ years old. The present findings suggest that the formation and development of dentition in the mouth of Salverinus pluvius are associated with the age rather than with body length.

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The authors conducted an anthropometry of the head and face and measurement of the dental arch on Chinese Hoklo (male 78, female 62) in 1978 and obtained the correlation between head-face and dental arch. Their age variation and traits were compared with those by Kutsuna and Arai (1943), Yang (1947) and Kanda (1974). The main results are as follows.
1) Anthropometry
The variation in age apparently showed in both male and female the head form became more brachycephalic and the facial form wider on the upper part and narrower on the lower part.
2) Correlation It seemed that the traits of Chinese Hoklo were as follows. For male any significant correlation was not found between bizygomatic breadth and upper dental arch breadth nor between bigonial breadth and lower dental arch breadth. But significant positive correlation was shown in the head length and lower dental arch breadth. In females, significant positive correlation was shown between bizygomatic breadth and upper dental arch breadth.

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Formocresol (FC) is routinely used for endodontic treatment of deciduous teeth. It has high permeability to the root and strong antiseptic effects possibly by the denaturing proteins. Therefore, FC treatment may have some influence on the root resorption of deciduous teeth. The purpose of this study was to investigate the effects of FC on calcified tissue resorption. The difference in resorption between FC treated bone and normal saline (NS) treated control bone was examined by in vivo and in vitro methods.
Rat and rabbit calvariae treated with FC or NS were implanted into rats subcutaneously or intraperitoneally. Osteoclast-like cells were observed around the bone implants. The number of these cells was less in FC treated bone than NS treated but no distinct resorbing lacunae was observed. Calcium contents in both implants increased after implantation. The amount of Ca increase was significantly higher in NS treated bone than in FC treated bone.
Resorption of bone powder by macrophages harvested from thioglycollate-stimulated peritoneal fluid was assayed in culture system. Ca release from FC treated bone was always less than that from NS treated.
Therefore it is suggested that bone becomes resistant to biological resorbing activity by FC treatment.

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The effects of various concentrations of serum, ascorbic acid, and sodium diphenylhydantoin (DPH) in culture medium on cell proliferation and collagen fibrogenesis were morphologically investigated in rat skin fibroblasts.
The cell proliferative rate appeared to be dependent upon the serum concentration both in αMEM and DM-160 medium. But, the rate in αMEM medium was much higher than that in DM-160 medium. Fibroblasts in αMEM medium produced extracellular fibers stained positively by silver impregnation as early as 1 day after planting and accumulated collagen fibers in the intercellular matrix continuously throughout their logarithmic growth. This fibrogenesis was not affected by the serum concentration in the culture medium. The degree of fibrogenesis in DM-160 medium was less up to 3 weeks, and the amount of collagen in the cell layer increased thereafter.
Fibroblasts grown in DM-160 medium containing less than 1μg/ml ascorbic acid showed evidence of ascorbic acid deficiency when compared with cells grown in αMEM medium containing 50μg/ml ascorbic acid. Ultrastructural study demonstrated that ascorbic acid deficiency prevented the deposition of typical 64 nm-banded collagen fibrils; instead, finer, unbanded fibrils and microfibrils were deposited extracellularly. These results indicate that the fibroblasts require ascorbic acid to produce collagen fibers.
Addition of DPH to cultured fibroblasts resulted in stimulation of their proliferation and enhancement of collagen fibrogenesis.

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Abstract: A scar tissue caused by surgical operation prcduces several difficulties on orthodontic treatment for cleft lip and palate patients. In this study, the biochemical changes with age and wound healing process in rabbit hard palatal mucosa collagen were investigated.
Collagen crosslink analysis was performed by radiochromatography after NaB3H4 reduction, collagentype analysis by electrophoresis. Amino acid composition and water content were also examined.
In age-related changes, the main reducible crosslink was dihydroxylysinonorleucine (DHLNL) infetus. It decreased with age in the skin, but remained at considerable level in the palatal mucosa.Hydroxylysinonorleucine (HLNL) and histidinohydroxymerodesmosine (HHMD) increased in both tissues.Type III cc Hagen decreased with age in the skin, while in the palatal mucosa it was found at low levelin fetus, then increased rapidly after birth and finally decreased again.
In wound healing, collagen contents were elevated to a plateau in three months, but, hydroxyprolinecontents in insoluble fraction changed continuously. DHLNL was the major crosslink immediatelyafter excision, then HLNL and HHMD increased. These changes resembled those with age. Typedecreased with wound healing. A low water content, much reducible crosslinks and a slightly high levelof type M were characterized in the scar tissue one year after excision.
These results suggest that rabbit palatal mucosa and skin collagens have distinctive features as wellas common patterns in age-related changes and palatal mucosa collagen changes in the similar mechanismboth with age and wound healing.

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Lingual pits of upper lateral incisors are susceptible to caries and dens invaginatus is thoughtto be more susceptible to caries than lingual pits. Moreover, the invaginated incisors with non-cariescause pulp death and lead to radicular granuloma and cyst.
This study was carried out to investigate the reationship between invaginated teeth and caries, andinvaginated teeth and radicular cyst.
Out of 3484 maxillary lateral incisors examined, 108 incisors or 3.1% showed palatal invagination (dens invaginatus). Of the 108 teeth affected, 5 were found with proximal caries but the invaginatedpart was not carious. Only 2 incisors were carious in the invaginated part but the enamel on the bottomof the invagination remained intact. There were 3 prophylactic treatment at theinvagination orifice inthe dens invaginatus.
Eight teeth or 7.4% out of the 108 invaginated incisors led to radicular granuloma or cysts withoutcaries. This means that 0.23% out of all maxillary lateral incisors examined had radiculargranuloma or cysts.

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The fine structure of the duct systems (intercalated, striated and main excretory duct) of the Japanese monkey, Macaca fuscata, submandibular gland was observed by transmission electron microscopy.
The intercalated duct epithelium was composed of cuboidal cells. Many low electron-dense large granules (400-800 nm in diameter) were observed in the supranuclear cytoplasm. There were abundant free ribosomes, sacks of rough endoplasmic reticulum and well-developed Golgi apparatus in the cytoplasm. Myoepithelial cells were found within the basal lamina at the periphery of the intercalated ducts. The cytoplasm of the myoepithelial cell was occupied by small myofibrils consisting of bundles of myofilaments.
The striated duct epithelium was composed of columnar cells with basal infoldings. Many vesicles, which contain amorphous substances similar to that seen in the lumen, were present in the apical cytoplasm of the striated duct cells close to the intercalated duct epithelium. Many moderately electron-dense small granules (140-250 nm in diameter) were present in the apical cytoplasm of the striated duct cell. Both types of striated duct cells had coated pits and coated vesicles just beneath the luminal surface. They were also seen at the basal side. The fine structure was very similar to that of the rat submandibular and parotid glands.
The main excretory duct (MED) epithelium was pseudostratified and composed of light cells of Types I and II, goblet cells and basal cells. There were well-developed interdigitations between the light cells.
Tuft cells and dark cells, which were obsereved in the MED epithelium of the rat submandibular gland, were not present in that of the Japanese monkey.

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It is well known that the form of vomer and distribution of vomerine teeth are used to indicate the interrelationship of genera in the Salmonidae. But the variation and the growth of vomer and vomerine teeth have not been sufficiently cleared until now.
The form and the growth of vomer and distribution of vomerine teeth in the char, Salvelinus pluvius, are discribed and reported in this paper.
The cleared and stained larvae indicate that ossification of vomer begins between 40 days old, about 21.1mm in standard length (SL) and 60 days old, about 22.3 mm SL. The small unpaired membrane bone in the larval stage, 22-23mm SL, do not have a posterior shaft.
A very rapid growth of vomer takes place between 100 days old, 22.8mm SL and 120 days old, 38.7mm SL, and when the fish becomes about 39 mm SL, 120 days old, the vomer bocomes divided into an anterior part and a posterior shaft. The conical teeth begin to appear in the vomer from 50 days old to 100 days old, 22.1-22.8mm SL and when the fish is about 53.5mm SL, 150 days old, about five teeth are present on the anterior part.
In the young and pre-adult char, the vomer is shaped like an inverted boat hull, with a dorsal flat and ventral crest. Most of the vomerine teeth are borne in a series along the lower edge of the anteri-or enlarged part, and the tapering shaft is toothless. Some specimens (23 %) have short median ridges which bear vomerine teeth arranged vertically in a single series. Five char (12.5 %) among 40 preadult char showed the vomer without teeth.

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A study of whether or not the pain threshold is affected by light intensity, the pain sensitivityund ervarious light intensities was investigated by formalin test and 0.3% acetic acid-writhing test inmice. Mice exposed to low intensity of light showed hyperalgesic action, while under high intensitythey showed analgesia, and the linearity between pain and light intensity was observed.
Exposure to 2500 lux as stressful stimuli decreased pain sensitivity significantly and naloxone reversedthis analgesic action. Strong light-induced stress decreased the endorphin content of the brainstem, so it seems likely that the endogenous opiate system may have an important role in the analgesicaction observed after this type of stress.
Furthermore, effects of some hormones which were thought to be activated and secreted duringstress on pain sensitivity were studied.α-MSH, β-MSH and vasopressin showed significant analgesicaction. On the other hand, cortisol (substitute dexamethasone for cortisol) andmelatonin had marked hyperalgesic action. ACTH had no effect.
From these facts, it is suggested that analgesia induced by strong light results from regulationunder the balance of analgesia producing system which is controled mainly by β-endorphin and algesiaproducing system which is controled by melatonin, cortisol and the like.

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Intracerebroventricular (i. c. v.) injection of melatonin (2, 5, 10, 20μg/mouse) produced hyperalgesiadose-dependently in the hot plate and 0.3% acetic acid-writhing tests. Melatonin antagonized theanalgesic effect of μ-endorphin.β-MSH, which was thought to be controlled by the auto regulatory systembetween melatonin and α-MSH, caused analgesic action. Melatonin also antagonized the β-MSH-inducedanalgesia. Serotonin, structual analogue of melatonin, had significant analgesic effect and melatonincaused a parallel shift to the right of the dose-response curve of serotonin. Thus, it is suggested that the hyperalgesic effect of melatonin may involve the opioidergic systemdirectly or indirertly. Since there is competitive antagonism between serotonin and melatonin, it maybe that the melatonin-induced hyperalgesia also interacts with the serotoninergic system directly.

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Experiments were made to clarify the mechanism of melatonin-induced hyperalgesia and the following results were obtained:
1) Intracerebroventricular (i.c.v.) administration of melatonin (2-20μmouse) elicited hyperalgesic action does-dependently.
2) Hyperalgesia was also induced by chronic administration of melatonin, when melatonin was administered 96μday for 7days by subcutaneous implantation of mini-osmotic pump capsel.
3) Pretreatment of tetrabenazine (50mg/kg, s.c.), α-methyldopa (100mg/kg, s.c.), haloperidol (0.5mg/kg, s.c.), tolazoline (10mg/kg, s.c.), phentolamine (5mg/kg, s.c.) and propranolol (0.5mg/kg, s.c.) prevented the hyperalgesic action of melatonin. And brain contents of dopamine and noradrenaline increased by i.c.v. injection of melatonin.
So it is suggested that the dopaminergic mechanism in the CNS may play an important role in melatonin-induced hyperalgsia.
4) Marked change by pretreatment of p-chlorphenylalanine was not observed on melatonininduced hyperalgesia, so that serotonin may not be concerned in development of melatonin hyperelgesia.
5) Melatonin potentiated morphine analgesia significantly, and morphine analgesia disappeared in pinealectomized animals.
6) From the fact that naloxone reversed melatonin-induced hyperalgesia, this hyperalgesic effect may be involved the endogenous opiate system.

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Serotonin-like immunoreactivity in the circumvallate taste buds of untreated and serotoninor 5-hydroxytryptophan (5-HTP, a precursor of serotonin)-treated mice were investigated by a modified PAP method with light microscopy and protein A-colloidal gold method with electron microscopy. As a control, supraependymal nerve plexus was immunostained by the same metho.
In both untreated and serotonin-treated mice, no specific immunostaining was seen in the taste bud, whereas supraependymal nerve plexuses of the lateral and third ventricles contained nerve fibers showing a distinct serotonin-like immunoreactivity. After intraperitoneal injection of 5-HTP, some taste bud cells showed serotonin-like immunoreactivity. Under electron microscopy, colloidal gold particles representing serotonin-like immunoreactivity were seen in the cytoplasm, nucleus and dense-cored vesicles in the type III cell. Positive immunoreaction of the taste bud and supraependymal nerve plexus disappeared by preincubation of the anzi-serotonin serum with serotonin-creatinine sulfate. Immunostaining was not affected by preincubation of the antiserum with 5-HTP.
Functional significance of 5-HTP uptake and serotonin synthesis in the type III cell was discussed with particular refernce to taste sensation.

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Koilocytotic atypia was studied histopathologically in five hund red and one cases of biopsy materials. Two hundred and seven cases had koilocytotic atypia. Inmany specimens the koilocytotic atypia was observed as a focal epithelial change. The 20-39 age group, which made up 29.9% of this age group, was uncommonly affected. Koilocytotic atypia was most common in papillo ma (75.0%) with statistically significant differences in the lesions and high occurence in the lesion ofthe tongue at oral sites. The relation between the results of these findings and its association to viral inf ection of the oral cavity was discussed.

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The present study was carried out to establish the culture condition, namely, which chemically defined medium (F12, Eagle's basal medium, minimum essential medium, Dulbecco's modified Eagle's medium, RPMI 1640, 199), what kind of serum (calf serum, fetal calf serum) and which concentration of the serum are the most adequate to increase rat incisal pulp cells. The area occuqied by outgrowth cells and maximum cell density were measured by using the explant culture technique. Following subculture, cell counting estimation was performed in some cases. The present results suggest that minimum essential medium supplemented with 15 per cent of fetal calf serum is the most adequate to increase of the incisal pulp cells in culture.

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A histological study and an autoradiographic study using tritiated thymidine were carried out to investigate the effect of colchicine on the epiphyseal growth cartilage of rat tibia, especially in relation to the function of microtubules.
Intravenous injection of colchicine (1.0 mg/l;kg) thickened the growth plate during the period from 3 to 5 days after administration. This was mainly due to an increase in number of hypertrophied chondrocytes. During the same period, the osteoblasts and the osteoclasts were detached from the trabecular bone at the junction of growth plate and metaphysis. The invasion of capillaries to the open end lacunae of the growth plate decreased remarkably (P>0.01). Appearance of thin trabecular bones in the metaphysis was noted.
Autoradiographic study showed that following a decrease in number of labeled proliferative chondrocytes during the period from 2 to 8 hours after the colchicine administration, the number of labeled chondrocytes increased remarkably (P>0.01). Labeled osteoprogenitor cells at the junction of growth plate and metaphysis decreased (P>0.01) at 3-5 days after colchicine administration.
At 6-10 days after administration, the thickness of the growth plate began to decrease with continuous erosion of the calcified cartilage septa. The invasion of capillaries to the growth plate was restored gradually and then osteoblasts and osteoclasts reappeared on the surface of spongiosa. The number of labeled osteoprogenitor cells and proliferative chondrocytes returned to a normal level.
These results suggest that colchicine treatment induced the synchronization of mitosis of proliferative chondrocytes in the growth plate. At the same time, colchicine treatment retarded the erosion of calcified cartilage matrix at the junction of growth plate and metaphysis and reduced the bone remodeling process of pongiosa which may have caused the increase in thickness of the growth plate.
These actions of colchicine may be closely related to the inhibition of microtubular function of cells engaged in the process of endochondral ossification. Introduction Endochondral ossification

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Though fluorescent X-ray spectrometers have been applied for analysis of trace elements in many fields, few studies were reported on the odontological use of this method.
In order to obtain a simple and quick analytical method for trace elements in deciduous teeth, pH of sample solution, APDC amount to be added, andaging time for precipitation were mainly examined.
A deciduous tooth was dissolved by H NO3 and a metal complex was formed in which APDC bonded with trace elements in the tooth solution. Then, trace element analysis was carried out by a fluorescent X-ray spectrometer after the precipitation was collected on the Millipore filter.
As a result, trace elements such as Cu, Zn, Pb, and Fe in primary teeth were determined quantitatively and it was elucidated that data were obtained without interference when excesses in the amounts of Ca and PO₄ existing in teeth were removed, because the APDC did not form any precipitation with Ca²⁺and P⁸⁺.

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An accurate mesurement of trace element-Cd, Zn, Pb and Cu-in small tips of human deciduous teeth was performed using a flameless atomic absorption photometry equipped with an automatic sampler.
Samples were prepared from defoliated human deciduous second molars divided into two layers of enamel and three layers of dentin i. e., outer and inner enamel and/or enamel side, middle and pulp side dentin each weighing approximatery 2 to 5 mg dry weight. After being resolved in HCl, trace elements were separated chromatographically from an excess amount of Ca using acetone-HCl solvent with a cation exchange resin.
In dentin, the elements excepting Cu were concentrated at the pulp side dentin. In enamel, Pb and Zn were concentrated at the outer layer. This might be due to the transfer from pulpal fluid and saliva to the mineral after tooth eruption. The average values of trace elements in enamel and dentin were determined as 1.09±0.44 and 0.76±0.44 (μg/g) for Cd, 167.55±11.74 and 156.04±18.29 for Zn, 18.00±1.20 and 28.04±2.80 for Pb and 7.16±1.93 and 5.55±1.23 for Cu, respectively.
These findings provide us with unique techniques both in terms of an accurate trace element analysis of teeth and also evidence in human deciduous teeth indicating heavy metal contamination of the human body due to pollutants in our environment.

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We examined 898 isolated molars of murid rodents from the middle Pleistocene deposit of Ando Quarry in Mine City, Honshu, Japan. Fossil molars were apparently divided into two species of Apodemus by its size except M3. Larger (L-type) and smaller (S-type) species of the fossils were thought to have close relations to living A. speciosus and A. argenteus, respectively. Dental parameters, which indicate size (MD, BL and REC) and shape (BL/MD index) of teeth, were used for comparisons between the molars of fossil and living species. Living species used in this study were collected in Mine City. It was found that L-type and S-type molars of fossils were generally smaller than those of living A. speciosus and A. argenteus, respectively. MDs of M1 in L-type and S-type were exceptionally larger than those in the living equivalents. The molars of two fossil species were generally slimmer than those of living species by shape comparisons using BL/MD index. These results suggestthat L-type and S-type of the fossils are not necessarily the same species as living A. speciosus and A. argenteus, respectively.

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Prolactin (LTH) influences calcium regulation. However, its direct effects on calcium transport in cells has not been reported.
In the present study, LTH (200 μg/ml) was shown to have an effect on specific rat cell populations obtained by sequential collagenase digestions of 18-20-day-old fetal calvalia. After 6 days in a routine culture of the cells, the cell populations (P1 Periosteal fibroblast, P2: Osteoblast, P3: Osteocyte) were used for the experiments, at 37°C and pH 7.10±0.02.
In P1, LTH had no effect on the Ca release and uptake. In P2 and P3, LTH decreased the Ca release 20-54% under the control values, and increased the Ca uptake 42-116% over the control values. These effects appeared rapidly within 5 min after the administration of LTH.
Previously, we have reported that LTH-induced effects on the Ca transport in mixed populations of P2 and P3 depend on the concentrations of LTH and also that they increased to approximately twice at 4°C. These results are almost similar to those of parathyroid hormone (PTH).
The present results suggest that LTH have the ability to act directly on organs or cells involved calcium regulation in a manner that is independent of vitamin D.
Part of this study was supported by a grant from the Ministry of Education, Science and Culture of Japan.

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Attempts were made to liberate aminopeptidase from cell membranes of Mycoplasma salivarium ATCC 23064. The membranes were separated from the organism cells sonicated and treated with DNase and RNase ; and incubated at 37°C with varying amounts of DOC, SDS, Triton X-100, Tween 80, Brij 35, CHAPSO, digitonin or EDTA for 15 min, and trypsin or papain for 2 h. SDS seemed to be most effective.
Approximately 80% of aminopeptidase activity and 90% of membrane proteins were solubilized by treating 1 part of the membranes with 2.5 parts of SDS by weight. Triton X-100 solubilized the activity only slightly but 66% of the protein s.
Based on the results, the following procedure for partial purification of the enzyme was devised. First of all, the membranes (1 part) were treated with Triton X-100 (5 parts), and centrifuged at 40, 000 g for 1 h. The sediment (1 part) was treated with SDS (3 parts) or papain (1/20 parts), and recentrifuged. The supernatants were chromatographed on a Sephacryl S-300 column. Thus, partially purified specimens were obtained. However, the specimen solubilized with SDS was water-insoluble, whereas papain produced a water-soluble specimen, the activity of which accounted for about 50% of the activity of the membranes. Therefore, it seems that treatment with Triton X-100 and papain is a favorable procedure for liberation of the enzyme from the membranes.

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This study was attempted to elucidate the ultrastructural and cytochemi cal characteristics of lingual dentin formation of rat incisors where no subsequent enamel formation took place. Special attention was paid to the initial calcification mechanism of mantle dentin by matri x vesicles.
The ultrastructural characteristics of the developing lingual dentin from the regions near the cervical loop to the established calcified dentin resembled those of the labial dentin formatio n of rat incisors except for the cytodifferentiation of inner enamel epithelial cells (IEE).
Enzyme cytochemistry of Ca²⁺-Mg²⁺-ATPase was performed using a modified Sundstrom and Mornstad's method after decalcification with EDTA. Near the cervical loop area, intense reaction products were demonstrated in the plasma membrane of the outer enamel epithelial cells as well as IEE. In the area where matrix vesicle calcification appeared, reaction products gradually disappeared from IEE and conversely were demonstrated in the plasma membrane of odontoblasts as well as the matrix vesicles. All the reactions disappeared once the dentin calcification was established.
Alkaline phosphatase (ALPase) was seen in the distal plasma membrane of IEE in the vicin - ity of the cervical loop, and its intensity gradually decreased towards the site of the initial calcification. The reaction products were also seen in the matrix vesicles as well as in the plasma membrane of odontoblasts at the more advanced stage. The closer to the initial site of calcification, the more strongly the odontoblasts and matrix vesicles reacted. When a layer of calcified dentin was established, the enzyme activity gradually decreased from the odontoblasts.
The results of this study suggest that both Ca²⁺-Mg²⁺-ATPase and ALPase activities play an important role in the initial calcification of dentin and that the matrix vesicles in the lingual dentin of rat incisors may be derived from odontoblasts.

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To elucidate the migration mechanism of a muscle attachment during growth, the attachment of the deep layer of the masseter muscle to rat mandibles aged 50 to 80 days was examined by light microscopy, polarized light microscopy and lead-labelling technique (Okada & Mimura, 1938).
The deep layer of the masseter muscle was divided into three attachments, according to the arrangement of attached fibers at the interface between bone and muscle and the ossification type at the bone surface.
In the periosteal attachment, endomysium of muscle fibers attached solely to the fibrous layer of the periosteum and immature Sharpey's fibers extended occasionally from the periosteal fibrous layer to the bone surface which revealed lamellar periosteal ossification. In the tendinous attachment, the tendon attached to the mandible through the fibrocartilage tissue which consisted of the plexus of immature fibers and the active fibrocartilage cells, and serrate fibrocartilaginous calcification was observed at the bone surface. In the transitional zone, the mode of attachment was a transitional type of both the periosteal and the tendinous attachments, and serrate periosteal ossification was observed.
It was concluded that the mode of attachment changing from the tendinous attachment through the transitional zone to the periosteal attachment may be caused by rearrangement of the attached fibers during growth and the mode of ossification changed from fibrocartilaginous calcification to periosteal ossification. These results suggested that the attachment of the deep layer of the masseter muscle to the rat mandible migrated, maintaining the relative position to the mandible.

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Four products of benzo [a] pyrene formed from the reaction of myeloperoxidase, hydrogen peroxide and chloride or bromide, termed products I_cl, II_Cl, I_Br and II_Br, were isolated by Reversed Phase-HPLC. The purified products were analyzed by FD -MS and light absorption and fluorescence spectrophotometries. In the FD mass spectra of products I_cl, and I_Br, the ions, [M+³⁵Cl-H] ⁺, [M+ ³⁷Cl H] ⁺, [M+⁷⁰Br-H] ⁺ and [M+⁸¹Br-H] ⁺, were observed as high intensive ions. From this result it can be concluded that products I_cl and I_Br were derived from benzo [a] pyrene through replacement of a hydrogen atom by one chlorine or bromine atom. In the case of product I_cl, it was also confirmed to be a chlorinated compound by tracer experiment using a radioactive isotope, chlorine-36.

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Prostaglandin E₁ was oxidized into five products in the presence of myeloperoxidase, hydrogen peroxide and chloride. One of these products was separated as a single component, which had light absorption peak at 293nm and was termed prostaglandin E₂₉₃, by thin layer and reversed-phase high-performance liquid chromatographies. By tracer experiment using a radioactive isotope of chlorine (chlorine-36), prostaglandin E₂₉₃ was confirmed to be a chlorinated compound. Spectrophotometrically, it was observed that in a basic solution prostaglandin E₂₉₃ was converted into a compound having light absorption peak at 288nm through a transient intermediate which was short-lived and had light absorption peak at 296nm. The second product having light absorption peak at 288 nm was separable as a single component by thin layer and reversed-phase high performance liquid chromatographie s. Prostaglandin E₂₉₈ was easily reduced by borohydride. The product reduced had a light absorption peak at 275nm. This product was also separable into two components by thin layer chromatography. The two components might be an epimeric compound with stereo- specifically different hydroxyl group formed by reduction of the keto group in the prostaglandin E₂₉₃ molecule.

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We evaluated the effects of drugs that included water extracts of Carthamus tinctorius L (E-C), β-glycyrrhetinic acid (Gly.), carbazochrome (Carz.), alone or in combination with (Mx.) and chlorhexidine (CHX) on the inflamed gingiva induced by accelerated plaque accumulation in Beagle dogs. After a clinically healthy gingiva was obtained by means of scaling and tooth brushing for 4 to 6 weeks, gingival inflammation was induced by the placement of silk floss ligatures around the premolars and molars and by feeding a soft diet for one week. The drugs were topically applied with a silicon gum tray for 5 and 10 days after inducement of gingivitis. A significant reduction of the number of infiltrated PMNs in the connective tissues adjacent to the upper part of the sulcular epithelium was observed with all drugs applied to gingiva at 10 days after the application. These findings suggested that E-C, Gly., Carz., as well as CHX are effective in the treatment of gingivitis singly or in combination.

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A density fractionation procedure has been used to study the characteristic proteoglycans of bovine alveolar bone at different degrees of mineralization. Bone powder fractions were extracted with 4 M guanidium chloride (GdmCl) and subsequently demineralized with 0.5 M ethylenediamine tetraacetic acid (EDTA) containing protease inhibitors. Alveolar bone powder was distributed into density fractions from 1.8 to 2.1 g/cm3. The amount of non-collagenous proteins markedly decreased with increasing density. Hexuronic acid content was also decreased with increasing density. Chromatographic analysis of the proteoglycans indicated three species of proteoglycans in these extracts. A large proteoglycan, present only in GdmCl extract (corresponds to non-mineralized region), diminished with increasing density. A relatively small proteoglycan was present in both GdmCl and EDTA extract (mineralized region). The amino acid composition and immuno reactivity of each small proteoglycan was similar. Yet, all three proteoglycans were cross-reactive with anti-small proteoglycan. These data suggest that the decrease of proteoglycan and the change of its size is related to the mineralization process in bone.

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Osteoblasts are distributed in a single layer along the surface of the bone matrix. While several type of osteoblasts are recognized during the process of bone matrix formation, osteoblasts active in the formation of the bone matrix possess extremely well developed rough endoplasmic reticulum and Golgi apparatus and exhibit the morphology of plump typical collagen formed cells. We therefore investigated the organelles of the osteoblasts that possess the ability to actively form the matrix of bone on the basis of the dilute osmium digestion method of Tanaka et al. and a high resolution scanning electron microscope.

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Eugenol has therapeutic effects on the dentin and pulp and is used routinely as an antiseptic and anodyne in dental practice in the form of zinc oxide-eugenol mixture. However, this drug acts as an irritant and induces inflammation reaction. Recently, it was reported that eugenol was released from mixtures of zinc oxide-eugenol into pulpal space trough the dentin.
Neutrophils accumulate at the inflammatory sites and act as scavengers. Once the cells are activated, various oxygen metabolites which have been implicated as putative mediators of tissue injury associated with the inflammatory reaction are produced. This paper describes eugenol-mediated O₂- production of guinea-pig neutrophils and the effect of the O₂- generation by N-ethylmaleimide (NEM) and azide.

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The taste organ in the frog tongue is situated at the summit of the fungiform papilla. Morphologically, the frog taste organ is usually called the taste disk rather than taste bud. It comprises many taste cells which respond to various taste stimuli with depolarizing receptor potentials. There are many axon terminals at the base of the taste cell layer in the frog, and it has been found that there exists a chemical synapse between a frog taste cell and a gustatory axon terminal. It is considered that a depolarizing receptor potential in a taste cell elicited by a taste stimulus may release a transmitter from the cell, and then the postsynaptic potential in the axon terminal membrane evoked by the transmitter may trigger an initiation of gustatory neural impulses.
Although it has been supposed that gustatory neural impulses may be initiated at the first node of Ranvier on the gustatory nerve fiber, obvious evidence has not been obtained until recently. In order to clarify the initiation site of gustatory neural impulse, it is important to examine the course of single gustatory nerve fibers within the fungiform papilla as giving attention to the spatial position of nodes of Ranvier.
The purpose of the present experiment was to examine histologically the sensory innervation of the frog taste disk and to determine electrophysiologically the initiation site of gustatory neural impulses.

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