The present study describes the basic structural features and characteristics of crystals obtained using high-resolution electron microscopy from sections of adult human enamel.
The human enamel crystal ultrastructure has been observed at near atomic resolution, and the basic hexagonal pattern of the unit cells in the hydroxyapatite structure viewed down the c-axis has been observed directly.
The destruction of enamel crystals caused by electron beams is similar to that caused by caries.
When crystal structures are destroyed by electron beam damage or caries, the crystal destruction always occurs in the unit of hexagonal cells without exception even in the crystal surfaces, and they are expanded along the (100) lattice planes.
Human enamel crystals have a considerable number of lattice imperfections, such as dislocations, vacancies of the atoms which constitute the hexagonal cells and substitutions. These lattice imperfections become weak points to electron beam damage and to caries, and crystal destruction occurs preferentially in these regions. The crystal surface is also composed of a series of units of the hexagonal cell, and these outer regions are easily susceptible to damage by electron beams.
Micro-pores can be present between fused regions of the enamel crystals.
The fusion follows the basic hexagonal cell unit pattern. Defects or faults may be found associated with the line of fusion or related to the micropores.

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Fuchsin basic and acid red No.106 known as probes for diagnosis of dental caries were oxidized by neutrophil peroxidase (myeloperoxidase), hydrogen peroxide and chloride in an acidic solution. The same reactions were also observed with polymorphonuclear leukocytes, hydrogen peroxide and chloride. By these reaction systems, myeloperoxidase-hydrogen peroxide-chloride system and white cellhydrogen peroxide-chloride system fuchsin basic was completely decolorized. The product of acid red No.106 oxidized by the myeloperoxidase-hydrogen peroxide-chloride system had a light absorption peak at 586 nm (blueviolet), and this product was separable by high pressure reverse phase partition liquid chromatography. These results suggest that fuchsin basic and acid red No.106 can be metabolized by the myeloperoxidase system in neutrophil.

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It was found that, by using ion analysis technique, the chlorine existing in enamel and dentine purified from human tooth (mandibular third molar) was highly soluble in an aqueous solution so that the amount of chlorine in the enamel and dentine dissolved as chloride ion was measurable. When the measurements were carried out in 0.25 M acetate (pH 4.0), the results showed that both noncarious enamel and dentine, and carious enamel and dentine contained 708±14μg/g (Mean±S. E., n=4), 11, 168±124μg/g (Mean±S. E., n=4), 718±4μg/g (Mean±S. E., n=4) and 5, 814±193μg/g (Mean±S. E., n=4), respectively. Thus, each noncarious and carious dentine contained a much larger amount of chlorine than enamel and carious dentine contained only half the amount of chlorine as compared with noncarious dentine. The solubility of chlorine in the enamel and dentine was unchanged in the region of pH of 4.0 to 9.0, but was strongly affected by ionic strength in the solvent. That is, accompanied by decrement of ionic strength the amount of chloride ion released from the enamel decreased, while contrarily it increased in the case of dentine. The present result suggests that chlorine in the human dental enamel and dentine exists in“salt form”.
Furthermore, we found that in the oxidation reaction of aflatoxin B₁and tetracycline by myeloperoxidase, H₂O₂and chloride ion the supernatant of suspension of dental hard tissue, especially of the dentine, could be substituted for chloride ion in the myeloperoxidase system. On the contrary, however, the supernatant in the suspension of enamel exhibited less activity. This difference may be dependent upon the concentration of chloride ion released from the enamel and dentine.

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The tongue is narrow, long and spatula-shaped. The oral part of the tongue is long while the pharyngeal part short. The apex is thick and notched. A median dorsal sulcus is present anteriorly. In the central portion of the tongue there is a lingual prominence covered with filiform papillae arranged in rossette-shape. There is no trace of the foramen cecum linguae and sulcus terminalis.
Scanning electron microscopic observations were made on the fine surfaced structures of the lingual papillae in a Chinese hamster (adult male, 35-45g).
1. Some regional differences in form and size of the filiform papillae, small filiform papillae on the anterior part of the tongue, larger filiform papillae on the lingual prominence, and conical papillae on the root tongue were observed.
2. The fungiform papillae which assume circumvallate-like papillae with a shallow groove, were scattered among the filiform papillae over the dorsum, but not on the lingual prominence.
3. The single median circumvallate papilla was rounded and the surface granulated with small secondary papillae.
4. Foliate papillae which have six to seven ridges separated by five to six grooves were found anterior to the base of the glossopalatine fold.

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The secretory and functional characters of theα₁-adrenoceptor of the submandibular glands of rats were studied biochemically and pharmacologically by both in vivo and in vitro experiments.
The volume of saliva secreted by methoxamine stimulation, which is preferentially characteristic of α₁-adrenoceptor stimulation, sigmoidically increased with the doses; at a dose of 6 mg/kg it drastically increased and then maintained maximum levels in contrast to that of pilocarpine stimulation at a dose of 2 mg/kg which was found to be almost at maximum levels. Phenoxybenzamine, phentolamine and dihydroergotamine referred to as preferentially characteristic of α₁-and α₁-adrenoceptor blockage completely stopped salivation but other blockers did not.
The types of proteins secreted by methoxamine stimulation were dose dependent disc-electrophoretically; at higher doses the α-type but at lower doses the γ-type which is relatively similar to serum proteins in contrast to all doses of pilocarpine stimulation were found to be β-type. All other α-adrenergic blockers except dibenamine and three α-blockers, mentioned above, converted α-to β-types. However, other blockers such asβ-adrenergic, nicotinic, muscarinic and dopaminergic and clonidine referred to asα₂-agonist did not convert them at all. The types of proteins secreted by the glands were also not dependent on the levels of cAMP and cGMP. The types of proteins by the slices of the glands were also independent of the nature of stimuli with and without various blockers.
Molecular weights of the α-types of proteins were found to be different from those of β-types.
They were 6000 to 12000 and the latter 9000 to 330000 over the entire range. The proportional amounts of amino acid compositions were also different from those between two types of proteins.
The concentrations of potassium and inorganic phosphate in saliva elicted by α₁-adrenoceptor stimulation were higher than those of pilocarpine stimulation but in calcium and sodium concentrations the reverse was true although amylase activity and total sialic acid levels did not show any significant differences between the two stimuli.

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Sjögren's syndrome is now generally accepted to be a definite clinical entity with involvement of many organs, though little is known of its etiology. As an aid to clarification of its etiology, we attempted to describe histopathologically the arterial changes in the tongue and major salivary glands in four autopsy cases of Sjögren'ssyndrome; to point out the common arterialchanges; and to discuss some problems in the morphogenesis of the common arterial findings.
All the patients were females. Their ages on first admission were 58, 36, 55, and 21 years, respectively.
For histological examination, the arteries in the tongue and major salivary glands were classified by size and the diameter of the vessels was measured from the outer marign of the media. The classification of arteries is as follows. Large-sized arteries are more than 200μm indiameter; medium-sized arteries between100μm and200μm in diameter ; and small-sized arteries less than100μm in diameter. The caliber of the affected arteries in both the tongue and major salivary glands ranged from large-sized to small-sized arteries.
We observed fresh and old arterial lesions of the tongue and major salivary glands in Sjögren's syndrome. Acute lesions included fibrinoid necrosis and vasculitis. Chronic lesions consisted of intimal fibrosis, medial hypertrophy, and periadventitial fibrosis. The most frequently occurring alteration of arteries was fibrinoid necrosis and intimal thickening. Although the caliber of arteries with fibrinoid necrosis and vasculitis in the tongue was found to range from small-sized to large-sized arteries, those in the major salivary glands were localized as medium-and small-sized arteries. Pathological change in the intimal thickening was composed of edematous and fibro-cellular thickening. The morphogenesis of intimal thickening suggests two pathogenic pathways:(1) organization of vasculitis;(2) response to increased blood flow or increased blood pressure.
From these findings, it was suggested that the vascular changes in Sjjögren's syndrome are similar to those of periarteritis nodosa.

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L-ascorbic acid decalcification was used for electron microscopy of mammalian tooth germs. Immature enamel and dentine decalcified in 1-ascorbic acid were compared with specimens obtained with EDTA and the features of the ascorbic acid decalcification method studied. L-ascorbic acid decalcifies too h germs from dogs in less than 1/4-1/5 of the time it takes with the EDTA method. It preserves the organic matrix of enamel and dentine as well as in EDTA. Especially, enamel matrix was preserved better than in EDTA. These are two notable advantages of the ascorbic acid decalcification method. The rapid decalcification can raise the efficiency of experiments, it may prevent the dissolution of some compounds from the specimen and allow only minimal changes in the specimens during decalcification. The good preservation of organic matrix of the enamel may be useful for developmental studies of the tooth enamel. It is suggested that this L-ascorbic acid decalcification method can be put into practice for further studies of tooth enamel, in parallel with the conventional EDTA method.

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The purpose of this study was to investigate the immunochemical and chemical properties of Actinomyces amphiphiles (AcA).
AcA were extracted from Actinomyces viscosus ATCC 15987 in phenol-water (45%, v/v) and purified by gel-filtration chromatography of Sepharose 6B. Double diffusion test with AcA and rabbit antiserum, which obtained a immunized rabbit with wholeA. viscosusATCC 15987 cells, showed clearly the single precipitin line. Passive haemagglutination assay of AcA sensitized sheep erythrocytes with antiserum to whole cells resulted in haemagglutination of high titer. Colorimetric assays of chemical components of AcA revealed that total hexose (35.6%), glycerol (18.3%), phosphorus (0.9%) and protein (2.2%) were present. Amino sugar and amino acid analysis of AcA were performed in an automatic amino acid analyzer after acid hydrolysis of AcA. Glucosamine, galactosamine (molecular ratio, 7: 1) as amino sugars and glycine, ornithine, histidine, as amino acids were detected. Neutral sugar analysis of AcA by high presure liquid chromatography showed the presence of glucose, mannose and galactose. Other neutral sugars were not detected. Fatty acid methyl esters were prepared from AcA methanolysates, and their molecular species were investigated by gas chromatography and mass spectrometry (GC-MS). The fatty acid methyl esters from AcA consisted of even and odd-carbon-numbered acids ranging from C₁₂ to C₁₈. These results indicate that AcA have a unique profile as compared with lipoteichoic acids.

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Fetal bones are mostly formed by endochondral ossification. As a part of the scanning electron microscopic investigations of bone matrix formation, changes in the ultrastructures were observed on the cracked surface of the fetal femur (over 5 months old), with the following results: The central part of the trabeculae in the bone marrow cavity was formed by a calcified cartilage matrix. The central part of the calcified cartilage matrix was formed by calcospherites of about 1 pm in diameter.The surface of a calcospherite was formed by dense, crooked collagen fibrils and the internal part of the calcospherite was formed by dense collagen fibrils with many granular structures of about 300Åin diameter. Some of the calcospherites were fused incompletely at the calcified cartilage matrix and the surface and internal parts were compactly calcified. Around the calcospherites, many spherical structures of about 0.3μm in diameter were formed. The matrix of the cortical bone was mostly calcified but a part of the matrix was incompletely calcified. The incompletely calcified matrix was formed by dense collagen fibrils and many granular structures. In the gap of the calcifying matrix, collagen fibril bundles were observed. They were calcified at regular intervals. In the matrix of the cortical bone, the walls of the osteocyte lacuna were mostly formed by dense collagen fibrils. However, some of the osteocyte lacunar walls were formed by dense collagen fibrils and calcospherical-like structures of about 0.2μm in diameter, while others were formed by dense collagen fibrils and many granular structures.

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iochemical and morphological characteristics of polysaccharides synthesized from sucrose by extracellular enzymes from Streptococcus mutans were compared among serotypes a through g
Polysaccharides synthesized by the enzymes of serotypesa, dand g formed visibleaggregates and firmly adhered to glass surfaces, whereas those of serotypesb, c, e and f floated homogeneously and adhered only slightly to glass. The enzymes of serotypesa, dandgproduced a large amount of waterinsoluble polysaccharides (IP), but most portion of the polysaccharides of serotypesb, c, bandfwas water soluble (SP). IP consisted of only glucan and SP comprised glucan (a major component) and fructan.
The IP of serotypesa, bandg, as compared with that of serotypesb, c, eandc, 1) containedhi gher proportions of α-1, 3glucosidic linkage and α-1, 3, 6 branch, 2) showed higher susceptibility to a-1, 3 glucanase (serotype a excepted) and lower α-1, 6 glucanase sensitivity, 3) contained a larger amount of high-molecular-weight fractions and possessed higher intrinsic viscosity (serotype b except ed), and 4) had lower S. mutans cell-agglutination activity. Electron microscopic observation revealed that IP of all serotypes comprised double-stranded fibrils with short fluffy protrusions extending out of its periphery as well as fine single-stranded fibrils. In the IP of serotypesa, bandg, long doublestranded fibrils coalesced with single-stranded fibrils, forming large clumps, while the IP of serotypes b, c, e and f contained shorter double-stranded fibrils and formed smaller clumps.
Thus, IP ofS. mutans can be divided into two major groups containing serotypesa, bandgand typesb, c, e andf, and further into four subgroups containing typea, typesbandg, typeb, and typesv, e andfon the basis of the biochemical and morphological characteristics mentioned above. No similar grouping of serotypes was indicated for SP ofS. mutans by most chemical and morphological properties examined.

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Moiré photographs of the occlusal surface of the lower first molars of Japanese children were taken by means of a specially designed moiré contourograph apparatus. They were then used for three-dimensional measurements. The height of 5 cusps and some other points were measured by counting the contour lines. Horizontal distances between them were also measured. Sex differences in these measurements were found only in the distances corresponding to the mesiodistal crown diameter. There was no clear correlation of the five cuspidal heights to the horizontal distances between them.

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The taste buds in ICR mouse after bilaterally sectioning the gas tatoty nerves, followed by administration of monoamine precursor (5-HTP, L-DOPA), were investigated with light and electron microscopy as well as by fluorescent histochemically applying the Falck-Hillarp method.
Degeneration of the taste buds was seen conspicuously by the 7th postoperative day and virtually all taste buds were lost by the 10th day. The gastatory (type III) cells under degeneration, however, kept the ability of monoamine precursor-uptake.
Regenerating taste bud cells originated from the epithelial basal cells which were in contact with the terminal of the reinnervating nerve by the 14th day. In the early stage of regeneration of the taste bud, immature gastatory (type III) cells had monoamine precursor-uptake ability.
These results indicate that the gastatory nerves are essential for differentiation and integration of the structure of a taste bud. Further, they strongly suggest that the gastatory (type III) cells obtain monoamine precursor-uptake ability at a very early stage of regeneration, and that the uptake ability persists even in the denervated gastatory cells.

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There have been only few reports on the fusion process of the interfrontal suture. Using the mouse (C57-BL), the form and fusion process of the interfrontal suture were investigated with a stereoscopic, light, and electron microscope.
The following results were obtained. Interfrontal suture relates the cranial base with the falx cerebri and first fuston takes place at the rear area of the jugum limitans fossa olfactoria (j. 1. f. o.). This fusion process was observed histologically. During postnatal 6-7 days, for ossification of the right and left frontal inner plates, the cells between them are pushed up and down. At postnatal 8-9 days, due to occurrence of chondrogenesis of the cells, the right and left inner plates are connected with a secondary cartilage. It was observed that the area was relatively avascular during the cartilage formation. This cartilage showed metachromasia by means of toluidine blue stain. All cells which composed the cartilage indicated degenerating figures of necrosis, hypertropy, or vacuolation.Until postnatal 14 days, the cartilage was resorbed and replaced the bone marrow. Simultaneously, the right and left inner plates were connected with osseous tissue for progressive osteogenesis around the cartilage.
The factors of chondrogenesis of the cells between the right and left inner plates were discussed in these findings.

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The peripheral course of axons of the rat lingual motoneurons was studied by HRP injection to the hypoglossal trunk in combination with sectionings of the hypoglossal or cervical nerve components of the hypoglossocervical plexus. Furthermore, the sizes of the labeled lingual motoneurons were compared in cross sections with those of the labeled geniohyoid (GH) and thyrohyoid (TH) motoneurons, which are located close to the lingual motoneurons. Axons of the lingual motoneurons, lying in the main hypoglossal nucleus, mostly pass through the hypoglossal nerve to reach the tongue, while those of a few lingual motoneurons, lying at the medial portion of the ventromedial subnucleus in the caudal fourth of the main hypoglossal nucleus, pass through the first cervical nerve to the upper root of the ansa cervicalis before joining the hypoglossal nerve. The lingual motoneurons passing through the cervical nerve are intermingled with those passing through the hypoglossal nerve. The latter motoneurons, however, diminish in number while traced caudally, and finally in the caudalmost part of the main hypoglossal nucleus the motoneurons passing through the cervical nerve come to f orm the major part of this nucleus. The size and degree of flatness of the labeled lingual motoneurons are smaller than those of the labeled GH and TH motoneurons. The lingual motoneurons passing through the cervical nerve are smaller in size than those passing through the hypoglossal nerve. This difference between motoneurons passing through the hypoglossal nerve and those passing through the cervical nerve is similar to that in the GH motoneurons.

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The aim of this study was to observe whether there are any differences between the ultrastructural findings obtained by several procedures of routine CF and those obtained by QF, FSF for A-cells, ID-cells and CGT-cells of the rat submandibular gland and, indirectly, to clarify the availability of membranolytic agents and also the interaction between chemical agents and membranolytic agents in secretory granules of rat submandibular gland A-cells. As results, it was suggested that the availability of the agents and the interaction in the A-cells were present. Membranes of A-cells were preserved relatively well in rapid perfusion fixation of 1: 1 mixture of 1% O_sO₄fixative and 2.5% glutaraldehyde fixative following infusion of the same mixture fixative and of 1%O_sO₄fixative in several CF. Extremely good preservation of membrane structure of acinar secretory granules was achieved by the QF-FSF method. The secretory granules in the A-cells dispersed, and fused aspect usually was rarely observed. All membranes of granules in the A-cells, ID-cells and CGT-cells were preserved as a trilaminar structure in the FS-fixed sections. The outer leaflet of the secretory granule membrane in the A-cells, ID-cells and CGT-cells was observed as a thick dense line, and filamentous structures radiating from the outer leaflet of the limiting membrane and the microtubules associated with the granules to the granules were observed in the A-cells and CGT-cells in QF and FSF. A reverse relationship of intragranular matrix and intragranular substructure in the A-cells was observed in the routinely-fixed and FS-fixed sections, i.e., densities of the intragranular substructures were higher than those of the intragranular matrix in CF, although the former was lower in density than the latter in the FS-fixed sections.

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