The recent neuroanatomical, neurochemical and neuropharmacological mechanisms for pain and endorphin system are comprehensively reviewed. This paper contains the following chapters:(a) brief history of endorphins, (b) enkephalinergic fiber, (c) diversity of opiate receptor, (d) analgesic action of endorphins, (e) mechanism of the analgesic action of opiates, (f) analgesic mechanism in Lamina V type cell in the spinal cord, (g) endorphins in the peripheral tissues and especially in the dental pulp and (h) role of endorphins in the peripheral tissues for analgesia.

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Biliverdinp, rotoporphyrin IX, hematoporphyrin, protoheme IX (hematin), methemoglobin, metmyoglobina nd cytochrome c (oxidizedf orm) were degraded by myeloperoxidase-mediatoexdi dation reaction in the presence of hydrogen peroxide and chloride at low acidity

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Central fibroma occurring in the mandible of a 10-year-old girl was studied with light and electron microscopies. Under a light microscope, the tumor was found to be composed of polygonal fibroblastic cells and cross-weaving bundles of collagen fibers. Eosinophilic rod-like or droplet-like substances were observed in the cytoplasms of some polygonal fibroblastic cells. Linear substances, which were stained red by van Gieson solution, were also occasionaly found. The linear substances corresponded electron microscopically to fibrous structures and existed in the rough endoplasmic reticulum which was dilated and filled abundant fine granules. The fibrous structure showed a certain periodical arrangement composed of light bands (about 120Å in width) and dark bands (about 80Å in width) but no subbands. It was first thought that this fibrous structure was peculiar type of collagen fiber but detailed examination revealed that this structure was neither a mature banded collagen nor a fibrous long spacing collagen, and that it did not match any of the intracellular collagen fibers of various tissues and lesions reported in humans. By using a goniometer stage, this structure appeared in several strands, each strand being 200Å in diameter, and of honey-comb pattern in part. Furthermore, the dark bands appeared a row of several rhomboid beads in one direction.
This fibrous structure seemed to be the result of polymerization of excess fine granules in the dilated rough endoplasmic reticulum, but its true nature remained obscure morphologically.

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The carbohyrate chains in collagen and glycosaminoglycans (GAG) fron bovine glomerular basement membrane (GBM) were studied biochemically.
GBM collagen was hydrolyzed in 2N NaOH, and from the alkaline hydrolysate the carbohydrateamino acid complex was isolated by Dowex 50-X4 and Sephadex G-15 column chromatography. The carbohydrate-amino acid complex was additionally hydrolyzed in 0.1N H₂SO₄ for varying periods of time. Hexose and amino acid analysis of each alkaline and acid hydrolysate revealed that the carbohydrateamino acid complex was composed of glucose, galactose and hydroxylysine and that glucose and hydroxylysine were released by only alkaline hydrolysis, while galactose was observed at first by graded acid hydrolysis after alkaline hydrolysis. From the above results, it may be considered that the carbohydrate-amino acid complex was glucosylgalactosylhydroxylysine.
The composition of GBM GAG was studied by two-dimensional electrophoresis of intact GAGon a cellulose acetate strip and one-dimensional electrophoresis of intact and registant GAG to enzymatic digestion and nitrous acid degradation. Two-dimensional electrophoresis showed that the main component of GBM GAG was heparan sulfate with hyaluronic acid, chondroitin sulfate and dermatan sulfate contained as minor components. Further, each component was identified by one-dimensional electrophoresis of GAG registant to enzymatic digestion and nitrous acid degradation.

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The endogenous inhibitors of dopa decarboxlase in the rat submandibular gland are trypsin-like protease. We discussed whether or not these proteases were the same as the ones previously reported. The homogenate of the rat submandibular gland was frozen and thawed three times and the supernatant was subjected to isoelectric focusing; seven active fractions of trypsin-like protease (isoelectric point, 4.0, 4.3, 4.5, 5.1, 5.5, 5.9 and 7.2) were obtained. The effects of trypsin inhibitors and metal ions on these proteases were investigated.
The protease with an isoelectric point of 4.0 was similar to kallikrein of the rat submandibular gland. However, it had different properties from kallikrein. The proteases with isoelectric points of 4.3 and 4.5, respectively, may be salivain. The three proteases with isoelectric points of 5.1, 5.5 and 5.9, respectively, were different from the enzymes previously reported. We thought these three proteases were isozymes. Proteases with isoelectric points of 4.0 and 7.2 did not inhibit dopa decarboxylase activity.

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Electron microscopic observation was undertaken on tissues of radicular cysts obtained from 25 patients at the Department of Oral Surgery, Osaka Dental University Hospital, and the mode of degradation of collagen fiber was investigated.
1) At certain sites of the granulation tissue, where the tissue was edematous and metachromatic and the inflammatory cells were rather reduced in number, the collagen metabolism was most active and the predominant macrophages exhibited in smooth-surfaced vacuoles abundant phagocytosis and advanced degradation of single collagen microfibrils or their bundles. Phagocytosis was further confirmed in fibroblast-like cells, having both characteristics of the macrophage and the fibroblast, as well as in myofibroblasts, although the degradation was not so far advanced; fibroblasts revealed only extracellular fibrillogenesis. Collagen microfibrils lying in the extracellular space presented various degradation to a high degree, being sporadically intermingled with the fibrous long-spacing (FLS) type fibrils (Randall's type III).
2) Collagenase activity of the radicular cyst was examined according to Gross' procedure; it was positive in 15 out of 25 cases. Polyacrylamide gel disc electrophoresis pattern of the guinea-pig acidsoluble collagen after incubation with a concentrated culture solution of the radicular cyst was examined according to Nagai's procedure; it coincided with the pattern obtained in the metamorphosing bull-frog tadpole. The collagenase activity was further positive in the embryonic tissue of rat teeth during the first ten days after birth. Its positivity following incubation en masse of the isolated dental papilla indicates the origin of collagenase from the ameloblast and suggests a participation of the stratified squamous epithelium in collagenase production of the radicular cyst.
3) Following incubation in minute slices of the guinea-pig carotid artery and surrounding tissue with bacterial collagenase of moderate concentrations, there appeared a good number of the FLS type fibrils as in the radicular cyst.
4) Following auto- or homo-transplantation of Achilles tendon collagen in rabbit, histological examination revealed a predominance of foreign body inflammation, accompanied by infiltration of foreign body giant cells. Electron microscopic observation on the fourth and the twentieth days of the autotransplantation disclosed phagocytosis and slight degradation of the collagen microfibrils in smoothsurfaced vacuoles, as well as their advanced degradation in the extracellular space, accompanied by sporadic appearance of FLS type fibrils as in the radicular cyst.
5) From these findings, it was postulated that the degradation of collgen fiber takes place in the radicular cyst under active participation of the endogenous collagenase, accompanied by phagocytosis and digestion of the collagen microfibrils in the smooth-surfaced vacuoles of macrophages, myofibroblasts and fibroblast-like cells, as well as by enhanced degradation of the microfibrils in the extracellular space. The mode of occurrence of the FLS type fibrils was discussed.

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Dentin permeability of endodontic therapeutics such as formalin, formalin tricresol, 10 % paraform propylene glycol solution, phenol, Black's preparation, camphophenique, campholated phenol and modified phenol were studied in reference to their vaporization rate at 37°C.
Paper points which contained a constant volume of each drug were applied to the enlarged root canals (hand reamer, No.10-60) of extracted human teeth, and then the root apex and the coronal portion of the endodontic cavity were tightly sealed with carboxylate cement. The tested teeth immersed in 30 ml distilled water were incubated at 37°C for a constant time and the amount of formaldehyde and phenol permeated into the water through the dentin was determined. Vaporization rate of formaldehyde and phenol was also tested with the same drugs.
The results were as follows:
1) Formalin, formalin tricresol and 10 % paraform propylene glycol solution, in that order, diffused formaldehyde into distilled water.
2) Phenol, Black's preparation, camphophenique, campholated phenol and modified phenol, in that order, diffused phenol into distilled water.
3) A close correlation between vaporization rate and dentin permeability was observed.
The present results suggest that both the vaporized molecules of formaldehyde and phenol in the root canals diffuse into the dentinal tubules easily.

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The effect of epidermal growth factor (EGF) on clone MC3T3-E1 cells which have osteoblastic ability was examined morphologically and biochemically. The addition of EGF (0.4-50 ng/ml) to the culture dishes transformed the cells from their normal polygonal shape into a spindle-like morpho-.ogy. Cell transformation began after 8 hours following the addition of 10 ng/ml EGF. This hormone caused a significant stimulation of cell growth and increased the protein content of the cells at 2, 10 and 50 ng/ml. However, the same doses of EGF significantly reduced the hydroxyproline content. The addition of anti-EGF to EGF-containing cultures completely blocked such morphological and biochemical changes caused by EGF. EGF (10-50 ng/ml) caused a significant inhibition of collagen synthesis of the cells. Protein synthesis was stimulated by the same doses. and, as a result, the proportion of collagen to protein synthesis markedly decreased with increasing EGF concentration.

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The object of the present study was to demonstrate the relationship between calcium-phospholipid-phosphate complex (complex) and calcification mechanism.
The complex was extracted from the powdered dentin and bone which were obtained from male Wistar strain rats and male and female albino rabbits, according to the method of Boskey, et al.(1976), and it was shown that the content of complex in the dentin were nearly equal to that in the bone of both rat and rabbit.
Further, the components of the extracted complex were examined analytically, using colorimetric determination with thin layer chromatography and gas liquid chromatography and morphologically, using transmission electron microscopy, scanning electron microscopy, scanning-transmission electron microscopy and energy dispersible spectrometer. As results of these experiments, it was found that the complex consisted of spherical material (0.1 μm in diameter) composed of calcium, inorganic phosphate and various types of phospholipid (phosphatidyl serine, phosphatidyl inositol, phosphatidic acid), and that the contents of each component of complex in the dentin were nearly equal to those in the bone.
From these facts, it was suggested that the complex played a role in calcification mechanism.

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The secretory granules which emerge within the mucous cells of the submandibular gland are extremely small in size, but gradually grow in diameter and those sitivated right under the cell surface are large. It is understood that the granules are released ultimately from the cell through its surface.
It is known, however, that in almost all cases, small granules fuse with each other to grow in volume. A few reports are avail able concerning the fusion of granules and its assorted phenomena observed so far. The author madeuis observations by focusing on the secretory granules and obtained the following results. Small granules have a characteristic of fusing with each other, but they can neither penetrate nor fuse with plasma membrane. However, larger granules have the ability of fusing with plasma membrane, but they seem to have less capability of fusing with other granules.

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Degenerative and regenerative nerve fibers following pulpotomy were examined under a transmission electron microscope. One day after the operation, the degenerative nerve fibers were scattered over a relatively wide area: from the necrotic zone to hemorrhage area. The myelinated axons contained the ground substance and showed a wrinkling of the myelin, while the appearance of water in the unmyelinated axons were observed. However, both myelinated and unmyelinated axons under the hemorrhage area showed a normal appearance. Five days after the operetion, a typical axoplasm swelling was seen in the proximal stump. There were many organelles in this axoplasm: vesicles, mitochondria, dense bodies and lamellar bodies. At 7 days postoperatively, many unmyelinated axons surrounded by Schwann cell processes were observed under the preodontoblastic layer. These findings suggest that the proximal stump of the amputated pulp nerve changes into a growth end bulb.

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Resorption of the jaw bone by experimentally induced tumor was studied histologically and morphometrically. The animals used were C3H/HeN mice divided into the following groups: group I was indomethacin (IM) non administrated and group II was IM administrated. The histological differences of bone resorption were compared in these two groups. Each mouse of both group I and II was injected 20-methylcholanthrene in the masseter and neighboring tissue and the induced tumor was rhabdomyosarcoma and squamous cell carcinoma histologically.
1. IM non administrated group
The resorpted regions of the jaw bone were the buccal alveolar and lower marginal portions of the mandible and zygoma in various degrees. In some animals bone resorption was marked by tumor invasion into the periodontium of the incisor. The mechanisms in bone resorption were observed in the present experiment, one was osteoclast-mediated resorption, and the other was smooth-resorption of non involving osteoclasts. In osteoclast mediated bone resorption there were three histological types according to relation between bone and tumor tissue, i. e.(1) tumor tissue attached directly to the bone, (2) periosteum was present between the bone and tumor tissue, (3) fibrous tissue was present between the bone and tumor tissue. The average number of osteoclasts was 11.6 per 1 mm of bone surface in the region of (1) and 6.6 per 1 mm of bone surface in the region of (3). In smooth-resorption there were two histological types according to relation between the bone and tumor tissue, i. e.(1) tumor tissue attached directly to the bone, (2) periosteum was present between the bone and tumor tissue.
2. IM administrated group In osteoclast-mediated bone resorption the degree of bone resorption and the number of osteo-clasts in IM administrated group were less than in IM non administrated group, i. e. the number of osteoclasts in the region of (1) was 2.1 per 1 mm of bone surface, and 3.4 per 1 mm of bone surface in the region of (3). Smooth-resorption was observed only in the region where the tumor tissue was attached directly to the bone. The same morphological findings in osteoclast-mediated bone resorption were observed in the invasion of both rhabdomyosarcoma and squamous cell carcinoma.

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The effects of hormones on biochemical functions in the parotid glands were studied in vitro using rat parotid explants which were supported by siliconized lens papers at the surface of the chemically defined synthetic medium.
Isoproterenol (IPR) stimulated amylase secretion from the explants which had been cultured for 48 hours in Medium 199 and total amylase activity in the culture system increased gradually during the culture period. IPR also stimulated DNA synthesis in the presence or absence of insulin and dexamethasone. This stimulation was preceded by enhanced syntheses of RNA and protein and marked induction of ornithine decarboxylase (ODC). Similar effects on DNA synthesis and ODC activity were observed with epinephrine or norepinephrine but the responses were less pronounced than in those with IPR. DNA synthesis was also stimulated by insulin and dexamethasone. In this case, however, increases of RNA and protein synthesis and ODC activity in the prereplicative phase were not so remarkable as in the case of IPR. Dibutyryl cAMP raised ODC activity but was inhibitory on DNA synthesis.
These results suggest that the rat parotid explants maintain hormonal responsiveness for at least 48 hours and can be used as experimental tools for study of physiology of the parotid glands.

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we carried out experiments to induce autoallergic sialadenitis (EAS) in Buffalo, Wistar and Donryu rats. Histologically, induced sialadenitis were revealed in the focal lymphoid cell infiltration in the penductal areas, areas, and in the more extensive and diffuse lymphoid cell infiltration in the submandibular salivary gland parenchyma with degeneration and destruction of the acini. Prevalencce of EAS, which showed more than Grade I in White's classification, was 68% in Wistar, 44% in Buffalo and 38% in Donryu rats. The lesions were mild in degree (Grade I or II) in all of both Buffalo and Wistar rats, while moderate to extensive and diffuse lesions (Grade DI or IV) were found in a few Donryu rats. In all strains of rats, EAS occurred 1 to 2 weeks after immunization.

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For the purpose of observing the ultrastructure of the membrane bone during embryonal development, scanning electron microscopic investigation of the ultrastructures of the internal and external surfaces of the parietal bone in the fetus was carried out in the latter part of the embryonic period, with the following results:
Trabeculae had formed on the internal and external surfaces of the fetal parietal bone. Numerous cavities of blood vessels were opened among the trabeculae showing the vascular walls. On the external surface of the parietal bone a matrix of compact collagen fibrils running parallel in roughly uniform direction had been formed. The outermost layer, however, was composed of irregularly oriented reticular collagen fibrils. The internal surface of the parietal bone was under resorption. The resorbing surface consisted of numerous large and small resorption lacunae of varying shapes, the collagen fibrils exposed at the bottom of these lacunae showed different orientations, and osteocyte lacunae were observable in the lacunae exposed by the resorption.
Along the vascular walls of the blood vessels opened on the internal and external surfaces of the parietal bone a matrix had already been formed. Whereas the matrix was composed of compact collagen fibrils running parallel in almost uniform direction, its outermost layer was made up of irregularly oriented reticular collagen fibrils.

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Details of the properties of protease associated with matrix vesicle (M. V.) were studied. Bovine epiphyseal cartilage M. V. fraction according to Ali et al. were further fractionated by Percoll density gradient centrifugation by a modified method of Väänänen et al. Most of the acid phosphatase was removed by Sephacryl S-200 gel filtration. Alkaline phosphatase and protease activities were effectively seperated by deoxycholate (0.008%) treatment followd by Sephadex G-100 gel filtration. This protease fraction showed a 900 times higher specific activity than the Percoll fraction, optimal pH 6.5 against casein, single band on 7% acrylamide gel electrophoresis and complete inhibition with 0.1mM EDTA and o-phenanthlorine. Analysis of the digested proteoglycan on Sepharose CL-4B showed that this protease degrades proteoglycan as a trypsin-like mode. It is highly possible that the growth of hydroxyapatite microcrystal inside of M. V. may puncture the M. V. membrane and release the protease which promotes crystal formation at the calcification front.

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The cell surface-structure of the miniature pig's oral epithelium was examined with a scanning and transmission electron microscope. The distal surface of the superficial cells showed type HI or N microridges at the root of the tongue, and type V on the palate. The distal surface exposed by strip ping off the surface cells 15 times by using adhesive tape showed type III at the root of the tongue, and type El or IV on the palate. From the results, it is suggested that primitive types of microridges of the epithelial cells changed to mature types from the basal to the superficial layer in the epithelium. The proximal surface of both superficial and exposed cells with adhesive tape showed type I or II microprojections. Desmosomes were observed frequently at the distal part of these microprojections. The microprojections invaginated the inter-microridge space on the distal surface of the epithelial cell. These findings suggested that the microridges on the free surface of the superficial cells were the remnant structure of the connection between the distal and proximal surface of the cells. Moreover, intercellular boundaries of the epithelial cells were formed by two parallel ridges on the distal surface of the cells, while the cells formed intercellular grooves on the proximal surface of the cells. The attached borders on the distal surface of the epithelial cells entered the grooves and were bound by desmosomes.

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The purpose of the present studies was to clarify the significance of functional demand by occlusion on the periodontaligament (PDL) of rats suffering or recovering from lathyrism. 130 Wistar male rats, weighing 70-150g, were intraperitoneally given a 2.5 % aqueous solusion of aminoacetonitrile (AAN) in dosages of 200mg/kg daily, and divided into three groups. Group I: On the 15th day of the experiment, their upper left molars were extracted. Group II: AAN administration was stopped on the 14th day. Group la: On the 14th day of the final administration of AAN, their upper left molars were extracted. 3 to 5 rats of the each group were sacrificed at intervals of 6 hours to 14 days after extraction of the opposed teeth or the final administration of AAN. The specimens including the left mandibular molars were dissected and processed for electron microscop.
The PDL of lathyric rats free from functional stress showed rapid disappearance of the characteristic lathyric changes by 2 days after extraction followed by atrophic changes consisting of slender fibroblasts and some collagen fibrils approximately parallel to the long axis of the tooth.
In the PDL of rats recovering from lathyrism, the lathyric changes disappeared after a relatively short duration. The reformation of bundles of collagen fibrils occurred from about 5 days after final administration of AAN followed by reorganization of the functional structure.
On the other hand, the absence of occlusal force during the recovery process resulted in disuse atrophy instead of reorganization of the PDL.
The results of the present studies suggest that functional demand by occlusion plays an important role in reorganization of the PDL recovering from lathyrism as well as in preservation of lathyric changes and that the fibroblast participates in these processes in response to demand.

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Extracted sound deciduous human tooth enaml was exposed to an acousto-optically Q-switched Nd: YAG laser. The resistance of the lased enamel to demineralization in vitro and in vivo were examined histologically with polarizing microscopy, microradiography and scanning electron microscopy. The lased enamel which exhibited a bluish color in polarized light showed only a small amount of subsurface demineralization after exposure to an artificial caries system in vitro. Scanning electron microscopic observations of acid etched surfaces of the lased enamel cut in a plane parallel with prism direction showed reduced acid solubility of both the surface and the subsurfacenamel. The lased enamel tested in the human mouth showed a marked resistance to oral environmental influences. These results suggesthat acousto-optically Q-switched Nd: YAG laser irradiation may be an effective measure for preventing dental carie.

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The morphology and structure of the filiform papilla of a hamster tongue were studied by light andscanning electron microscopy.
Light microscopic findings revealed that the filiform papilla was composed of four cell columns-(i) anterior, (ii) posterior, (iii) posterior buttress, and (iv) lateral.
The morphology of the filiform papilla observed by scanning electron microscopy were dicussed in relation to the light microscopic findings.
The morphology and structure of the filiform papilla were schematically illustrated and also discussed from the viewpoint of the functions of the tongue.

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The nuclear DNA content of a tumor cell was determined by Feulgen cytofluorometry in 30 patients with pleomorphic adenoma to study the correlations between the nuclear DNA content and the histological types of the tumor, cellular atypia or clinical malignancy. Moreover, since a tumor histopathologically shows various aspects of proliferative changes, the histological patterns in the same tumor were also investigated using nuclear DNA content as an index. Tissue sections (10μ) were used for investigation by histological patterns.
From the results, the following were considered:
1) Appearance of polyploid is the key factor for differentiating the patients with pleomorphic adenoma from those with potentiality of malignancy. The reason why proliferation of the pleomorphic adenoma is slow seems to be that the cells at G₁ phase are predominant and the cells at S, G₂, or M phase are very few.
2) Proliferation ability is more increased in the salivary-duct-derived epithelial tumor cells than in the myxoid areas (which involves myoipithelium), the chondroid areas, and the myoma-like areas.
3) Semi-malignant pleomorphic adenoma and malignant pleomorphic adenoma are characterized by a shift of the major mode to 3c or disappearance of a stem line, appearance of polyploid over 5 % and an increase in the number of cells at S, G₂, or M phase along with a decrease in cells at G₁ phase. Therefore, even in pleomorphic adenoma with clinically benign findings, the appearance of polyploid or an increase in the cells at S, G₂, or M phase (especially when the rate exceeds 50 %) seem to suggest a possibility of malignancy.

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Development of the secretory end-piece of the rat submandibular gland and accompanying changes in the sympathetic innervation were examined by light and electron microscopes as well as fluorescent-histochemically (using the Falck-Hillarp method). The following results were obtained.
The terminal tubule, a rudimentary secretory end-piece, which appeared after a gestation period of 20 days, consisted of terminal tubule cells and proacinar cells. Fluorescent-histochemical examination revealed the invasion of fine nerve fibers, which emitted a green fluorescence, into the terminal tubules and the formation of large varicosities next to the secretory cells. Electron microscopic examination also demonstrated that these nerve fibers penetrated the basement membrane and contacted directly with the terminal tubule cells.
Acinar cells appeared and many large varicosities were observed within the terminal tubules 3-4 days after birth.
The proacinar cells completely disappeared 14 days after birth. Simultaneously, the number of varicosities decreased and fine nerve fibers appeared around the end-pieces. Electron microscopically, nerves in close apposition to acinar cells were also observed, but these nerves did not pass through the basement membrane.
The terminal tubule cells contained many large vacuoles 25-28 days after birth and a decrease in their secretory granules was marked. The terminal tubule cells were transformed into intercalated duct cells. At this time, the secretory end-pieces consisted of acini and their sympathetic innervation was almost the same as in adult rats.
These findings suggest the possibility that sympathetic innervation is involved in the development of the secretory end-piece of the submandibular gland.

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The growth of human dentine was investigated in an extracted deciduous lower second molar exhibiting more than twentysix tetracycline lines. It was concluded that:
1. The pattern of differential growth in lower deciduous molars differs from that in permanent molars.
2. These differences are probably due to variations in the pattern of the odontoblast's activity during its life cycle.
3. The dentine of the floor of the pulpchamber which constitutes the interradicular dentine grows generally more slowly but steadily than elsewhere.

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