Twenty five cases of operation material of the human tongue were studied histopathologically by serial sections, with paticular attention to the occurrence of cartilaginous tissue in the aponeurosis linguae. As a result, a few masses of the cartilaginous tissue, measuring 1.0 to 4.0 mm in length and 0.5 to 1.0 mm in thickness, were found in the aponeurosis linguae of two cases. Patients of these two cases had been suffering from carcinoma of the tongue, and had treated by irradiation with more than 10,000 rads of tele-Co 60. Ultrastructurally, chondrocytes had similar structurs to those of normal chondrocytes and the pericellular matrix tended to be composed of fine fibrils and proteoglycan granules. Intercellular matrix contained many electron dense and membran-bound bodies, and irregular-arranged collagen fibers.

It was thought that the cartilaginous tissues found in the aponeurosis linguae in the present study was a metaplastic origin, and that the irradiation was preceding factor of chondroid metaplasia.

The formation of aperiodic microfibrils perpendicular to the basal lamina of a mouse tooth germ and its nature were observed by light and electron microscopy. In addition, some histochemical examination of mucopolysaccharide and enzyme digestion were also carried out using the tooth germ of one-day-old mouse. In the dental bud stage of a 10 to 14-day-old mouse embryo, the basal lamina has been clearly formed, however aperiodic microfibrils and collagen fibers can not be observed. In the 16-day-old mouse embryo, a few formative aperiodic microfibrils were first observed in association with the basal lamina. In the epithelial-mesenchymal junction of the 18-day-old mouse embryo, fine collagenous fibrils appeared in addition to aperiodic microfibrils. A large number of aperiodic microfibrils which seemed to derive from the lamina rara interna were observed in the tooth germ of 20-day-old mouse embryo. Furthermore, in the predentine formative zone of the tooth germ of the one-day-old mouse, aperiodic microfibrils were well-developed, and distributed among the processes of the preameloblast. In the mineralization zone of the dentine matrix the aperiodic microfibrils were still present at the invaginated portion of the preameloblasts, but they had disappeared as a secretion of enamel matrix in the tooth germ of 2-day-old mouse.

The histochemical examination indicated that the aperiodic microfibrils were positive for RR and PAM staining, but they were negative for PAM staining after treatment by hyaluronidase or neu-raminidase. Also, aperiodic microfibrils were resistant to collagenase, pepsin and trypsin after hyaluronidase and/or neuraminidase treatment. These results indicate that the aperiodic microfibrils include hyaluronic acid and sialic acid. From these results, it was indicated that the aperiodic microfibrils were more similar to basal lamina than to collagen fibers.

Koilocytes were studied in oral papilloma from a 59-year-old man with transmission electron microscopy. The koilocyte was represented by irregular nuclei with coarse chromatin clumping. The clear perinuclear zone was almost completely lacking of a cytoplasmic component or an aggregate of some vacuoles. However, an increase of tonofilaments in the outer zone of the cells was noted. No virus particle was detected in the nuclei of the cells within the observed area.

Staphylococcus epidermidis has been thought to produce neither slime nor capsule, but we found that the organisms produced a large amount of slime when utilizing the dialysis membrane technique (DMT) applied for elastase purification.

Each Type strain of 12 staphylococcal species and ten of isolates of S. epidermidis from oral cavities were used for the examination of slime production. The strains that produced slime by the DMT, were S. xylosus and all of S. epidermidis, but no capsule was formed. Also S. epidermidis produced no slime either in aerobic conditions or in anaerobic, although the organisms grew well. Slime production was observed in the medium which included brain heart infusion or beef extract, but it was not observed in a medium such as trypticase soy agar, trypticase soy agar with 1% glucose or mannitol salt agar. The slime contained 6.1% (W/W) deoxyribonucleic acid, 6.3% (W/W) protein and 10% (W/W) carbohydrate. The viscosity of the slime decreased remarkably after protamine sulfate was added for DNA elimination. As a result of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, glycoprotein was found in the slime of S. epidermidis. The molecular weight was between 24,000 and 24,500 daltons.

From these result we infer that the viscous phenomenon was due to a relationship between nucleic acid and glycoprotein.

The present experimental study was a intended to make a detailed histological observation of the initial stage of epithelial proliferation in odontogenic tumor. The animals used in the present experiment were one-month-old Long-Evans rats, and 1-butyl-1-nitrosourea (BNU) was administered by gastric intubation (300mg/kg, four times at biweekly intervals) to each rat. The results were as follows:

In the control group, a few epithelial foci of the resting type were found in the periodontal ligament but no proliferating type was found. In the experimental group, scattered proliferative epithelial masses of various sizes and shapes were found in the periodontal ligament in 63.0 per cent of the animals. The largest epithelial masses showed a similar histological structure to those of the follicular ameloblastoma, i, e., the more peripheral of which were ameloblast-like in appearance with a loose central area simulating stellate reticulum of the enamel organ. Most proliferative changes of the epithelial components in the periodontal ligament occurred in the molar areas. There was no statistical significance between the frequency of epithelial proliferative changes in the periodontal ligament and the life span of the animals.

The present experiment can not be considered a complete animal model for the initial stage of odontogenic tumor but the mode of epithelial proliferative changes in the periodontal ligament may offer some suggestions for interpreting the development of odontogenic tumor.

Hyaline bodies found in dentigerous, primordial and multiple cysts were examined histologically and ultrastructurally, and their origin was discussed. In the present study, hyaline bodies were found in 11.5% of the dentigerous cysts, 11.1% of the primordial cysts and 33.3% of the multiple cysts. They occurred most frequently within the epithelial lining, but a few bodies were observed in the connective tissue wall. Histochemical reactions of hyaline bodies were similar to those of previously reported results by other investigators. In two cases of dentigerous cysts, the findings suggested a gradual transition of secondary dental cuticle to the hyaline bodies.

Ultrastructurally, hyaline bodies have a lamellated structure which is composed of alternate electron-dense and electron-lucent layers. Hyaline bodies adjoined epithelial cells via half-desmosomes. Epithelial cells containing well-developed cell organelles and electron-dense granules with various sizes were seen adjacent to the hyaline bodies. By scanning electron microscopy, the cut surfaces of hyaline bodies were found to be homogeneous, and the free surfaces were fine-lamellated. By electron probe X-ray microanalysis, inorganic elements such as P, S, Ca and Fe were present in the hyaline bodies.

The present results may assist in the clarification of the origin of the hyaline bodies in odontogenic cysts; the hyaline bodies may be intimately associated with epithelial cells of odontogenesis and may be derived therefrom, in the same fashion as the secondary delltal cuticles.

Oncocytes in human labial salivary glands were examined light microscopically and ultrastructurally, and the possible mode of development and a significance of these cells were discussed. For light microscopy, 154 cases of the human labial salivary glands were collected from autopsy cases, and serial sections were made. The designation of “oncocyte” was in accordance with Hamperl's description(1931). Materials for ultrastructural examination were obtained from five patients with mucocele of the lip. The results were as follows:

Oncocytes were found in 79.2% of 154 cases without sex predilection. Oncocytic changes in the human labial salivary glands had a tendency to be more frequent in the intralobular and interlobular ducts and less in the illtercalated ducts and the acini. Although oncocytes were noted in all decades of age, their proliferative changes were not found either in the youngest or in the oldest cases. There was no definite correlation between the oncocytic changes and atrophic changes of the salivary gland parenchyma.

By ultrastructure, the cytoplasm of the oncocytes was found to be completely filled with non-oriented mitochondria with or without intramitochondrial granules. Furthermore, oncocytes were classified into two types by their mitochondrial pleomorphism, i. e., the first type had mitochondria with normal in morphology and the other type had various mitochondrial pleomorphism.

There have been few reports of oral radiation death and the ethiology of this form of death has not been fully investigated to date.

The purpose of this paper is to clarify the genesis of oral radiation death.

The animals used in this experiment were ddN female mice weighing 23 to 26g. The mice were given X-irradiation to various areas of the head.

The results were as follows:

1. The mean survival time after 2400R irradiation was 12 days in the wholehead group, 14.8 days in the maxillary group and 16.8 days in the mandibulary group, respectively.

2. The spleen to body weight ratio (s/bw) of the control mice was 0.0098土0.0014 and the ratio s/bw of the starved irradiated mice decreased drastically to 0.0013土0.0007.

On the other hand, the value of the ratio on the irradiated mice decreased in proportion to the dosage and remained at nearly 0.0035.

3. There were no favorable effects on the survival rate of irradiated mice even when fed by forced nutrition. The excretion rate of ¹³¹I-HSA in the feces of irradiated mice increased relnarkably at an early stage of the irradiation to whole-head as compared to the control mice.

From these findings, it was thought the causes of oral radiation death may result from general irradiation damage to certain areas including the spleen and the intestines in addition to the starvatlon.

Two cases of squamous metaplasia in the minor salivary glands with pseudoepitheliomatous hyperplasia were reported. Case 1 was 32-year-old female who had been suffering from mucocele of anterior lingual gland, and Case 2 was 64-year-old male who had been suffering from carcinoma (squamous cell carcinolna) of the maxillary sinus. In the excised specimens taken from both cases, marked squamous metaplasia of the salivary gland epithelia with pseudoepitheliomatous hyperplasia which showed same histological appearance of necrotizing sialometaplasia was found. Especially in Case 2, islands of pseudoepitheliomatous hyperplasia co-existed with invading cancer nests.

The possible mechanism of pseudoepitheliomatous hyperplasia of squamous metaplastic cells in the salivary glands was discussed.