Merkel cell tumor have been reported in dermatology and there are no case reports which show them arising from the oral region except one case of the lower lip. We studied a Merkel cell tumor of the maxilla of a young female using light and electron microscopy as wellas immunohistochemistry. Furthermore, the relationship between the Merkel cells and the Merkel cell tumor was also investigated. The cytoplasm of tumor cell was positive for NSE and dense-cored granules were also observed. Desmosome like structures were detected among the tumor cells. Histopathologically, this tumor showed highly invasive activity.
These results suggest that this tumor originated from Merkel cells of the oral mucosa, and it is suggested that this tumor belongs to the category of malignant neoplasms.

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The parotid gland of the Japanese pipistrelle (Pipistrelus abramus) was examined histologi-cally and histochemically by light and electron microscopy
Light microscopically, the parotid gland of the Japanese pipistrelle was categorized as a homo-crine type of a compound acinar gland. The acinar cells contained clear granules in toluidine blue preparations. The well developed intercalated ducts contained a few secretory granules. The striated ducts showed a typical form. Histochemically, the acinar and intercalated duct cells contained both neutral and sialic mucosubstances, but the striated duct cell contained only neutral mucosubstance
Electron microscopically, acinar cells contained abundant secretory granules which were divided into two types. The first type of granule consisted of a less dense central matrix and peripherally arranged tubular substructures with their axes underlying a limiting membran. The other type of granule contained some small circles of the tubular substructure with axes in the central matrix and a similar substructural hem in the periphral area. The intercalated duct cell had a highly developed Golgi apparatus and a few granules containing a uniformly dense matrix. The striated duct cell was of the ordinary type and contained sometimes dense vesicles in the apical cytoplasm. Histochemically, in the acinar secretory granule, the central matrix and the axis of the tubular substructure contained mainly protein, while the peripheral matrix and the wall of the tubular substructure contained glycoprotein. Both granules of the intercalated and striated duct cells contained glycoprotein.
In one of the specimens, a few mixed acini chracteristic of mucous cells were found. In these acini the primary cells were in the form of demilunes. These cells were weakly PAS positive and strongly stained by Alcian blue pH 2.5 and pH 1.0. Thus their histochemical nature was unusual compared with normal mucous cells. We therefore considered that these mucous cells arose by a metaplastic transformation.

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The present study was to examine the effect of transforming growthf actor-&(TGF-&) on some functions and gene expressions of human periodontal ligament fibroblasts (HPLF). The cells were studied at passage number 5 to 10. TGF-& increased DNA synthesis and division of the cells in a dose-and culture time-dependent fashion. Since many studies have shown that c-myc gene, an on cogene, is involved in the proliferation and differentiation of cells, we examined the effect of TGF-& on the expression of the c-myc gene in HPLF. The mRNA level of c-myc in HPLF increased markedly when the cells were treated for 60 min with TGF-&. Also TGF-fi induced significantly the production of prostaglandin E2 of the cells. Further, alkaline phosphatase activity in the cells was also increased by treating with TGF-&. TGF-&-induced stimulation of alkaline phosphatase activity in the cells was examined at their mRNA level by using liver/bone/kidney alkaline phosphatase complemetary DNA. The mRNA level in TGF-&-treated cells increased in a dose- and culture time-dependent manner. These results suggest that TGF-& is an important regulatory factor in the metablolism of the human periodontal ligament.

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The structure of the dental roots of molars in Tupaia glis were observed.
In Tupaia glis, the upper molars had 3 roots, one of them located on the lingual side and the others on the buccal. The crista interradicularis, running between each root, was Y-shaped in the roots in the developmental stage, but it was not observed clearly in the complete molars. In the M³ the roots were rarely united. The lower molars had 2 roots, located mesially and distally. The crista interradicularis ran in a mesiodistal direction.
It is considered that the root patterns of the M¹ and M² in the dilambdodonta could be explained by the shape of each root and the outline of the occlusal view of the crown. The M³ was 3-rooted, and the lower molars were 2-rooted almost invariably in the dilambdodonta. The structure of the crista interradicularis seems to depend on the number of roots.

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The human oral spirochete, Treponema denticola ATCC 33520, possesses a major polypeptide antigen with a molecular weight of 53, 000 daltons (53kDa). The outer envelopes were prepared after the cells had been sonicated and then subsequently washed by centrifugation. Electron microscopy of the negatively stained outer envelopes demonstrated that polygonal structures approximately 8.5 nm wide were hexagonally packed and that three pores, each approximately 1.5 nm in diameter, were situated to form a three-eyed structure in each polygon. Using specific anti-53kDa antigen serum and protein A-gold conjugate immunoelectron microscopy also demonstrated that gold particles (size, 5 nm) appeared to adhere specifically to the polygonal structures or the three-eyed structures in the outer envelope, suggesting that the 53kDa major protein antigen may localize on the polygons or the three-eyed structures of the outer envelopes.

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We studied on the “acellular mineral deposition” preceding bone induction by bone matrix gelatin (BMG). It was thought that “acellular mineral deposition” was formed by accumulation of calcium and phosphate without osteogenic cells and matrix vesicles, and may be significant for differentiation of osteoblast. Several new methods were developed to study “acellular mineral deposition”. New bone, uncalcified BMG and cartilage could easily be distinguished by differences in their staining intensities with hematoxylin and eosin. Calcified areas of epoxy sections could be stained with alizarin red S by heating and drying at 120°C. Toluidine blue, basic fuchsin and methylene blue, and various other stains were used for the study of bone induction in epoxy sections. Simple methods involving electron probe X-ray microanalysis, electron diffraction and Fourier transform infrared spectroscopy (FT-IR) were developed for the analysis of minerals in sections prepared for histological observation.

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Localizations of transforming growth factor alpha (TGF-α) and epidermal growth factor receptor (EGF receptor) in 28 cases of oral squamous cell carcinoma were examined by using an immunohistochemical staining method. TGF-α was demonstrable in 8 of 11 cases of well differentiated and in 8 of 10 cases of moderately differentiated carcinomas, while was detected in 3 of 7 cases of early invasive carcinomas. The expression of EGF receptor was found in most cases except only each one of well differentiated and early invasive carciomas. From this fact, it seemed that the carcinoma tissue was readily able to adapt to proliferation by receiving the signal from the growth factor such as TGF-α via the EGF receptor. Therefore, it is reasonable to consider that a less number of positive cases of TGF-α in the early invasive carcinomas show a lower proliferating activity in these cases. Based on this viewpoint, early diagnosis and treatment are required in oral squamous cell carcinoma.

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To clarify the mechanism of decrease in the bactericidal activity of leukocytes in diabetes, rats with streptozotocin (STZ) diabetes were prepared for examination of the production of supero xide anion (O₂^-), a reactive oxygen produced by leukocytes, and the effect of insulin on this production. O ₂^- production was measured in microtiter plate wells by the cytochrome c reduction method. Opsonized zymosan, phorbol myristate acetate and Ca ionophore A 23187 were used as stimulants. The diabetic group showed a significantly higher blood glucose level, lower blood insulin level and lower O ₂^- production by macrophages with all three stimulants than those of the normal group. The amount of O₂^- produced by macrophages in the STZ-insulin group was slightly higher than that in the diabetic group. The diabetic, STZ-insulin and normal groups showed no significant difference in superoxide dismutase activity. There were significant correlations between the respective O₂^- production in re-sponse to the stimulants and the blood glucose level or the blood insulin level (p<0.01), respectively.These findings suggest that a decrease in O₂^-production in leukocytes is one of the causes of the decrease in the bactericidal activity in diabetes.

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