[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Although cheilosis, angular stomatitis and glossitis are recognized as characteristic symptoms of ariboflavinosis, essential pathogenesis of the lesions is still unknown.
In the present study, ultrastructural and biochemical changes of oral mucosa in rats fed on synthetic riboflavin deficient diet were examined.
An enzymatic study of oral mucosa in riboflavin-depleted rats showed a decrease of succinate dehydrogenase and lactate dehydrogenase. No changes in LDH isoenzyme patterns of oral mucosa were found, but there was a significant decrease in LDH-5 of the skeletal muscle (masseter). The tongue in riboflvin deficient rats has a marked increase in lipid peroxide content.
Scanning electron microscopy of angular mucosa in riboflavin deficient rats yielded a threedimentional view of densely arranged microplicae.
Transmission electron microscopic observation of the same specimen revealed that the mitochodria became slightly enlarged in the basal layer and that tonofilaments and keratohyaline granules exihibited a decrease in number and concentration in the superficial layer.
These results suggest that lipid peroxide raised in oral mucosa by riboflavin deficiency may play an important role in oral lesions.

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The inner surface of the mouth cavity as far as the beginning of the alimentary canal was examined in young specimens of this Salmonidae fish. Using radiographic techniques and after examination of unstained and alizarin red stained preparations, two groups of teeth were found in the pharynx of this fish. One group teeth was located on the two pairs of the upper pharyngeal bones and also teeth were found on the single pair of the lower pharyngeal bones.
The other group consisted of very small teeth situated on the “gill raker bones”, which are very small bones attached to the pharyngeal surface of the branchial arch skeleton. Histologically, both groups of teeth were found to have similar features to oral teeth. In other words, they are polyhyodont, and are attached via bony pedicles to the basal bone, having homogeneous dintin without any dentinal tubules.
However, in the development of these teeth, only the teeth on the gill raker bones have no dental lamina. According to the literature, “thorn-like” structures are present on the gill-rakers of many teleostei. Our observations show that the structures on the “gill raker” of Salmo gaird neri irideus are true teeth, and since they could be described as having a “thorn-like” appearance, we would like to point out that the “thorn-like” structures of other teleostei, referred to in the literature, might also be teeth indeed.

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The teeth of Chlamydoselachus anguineus, a living archaic fish, which was caughtin Suruga Bay, Japan, were investigated on their arrangement pattern, morphology, structure, attachmentpattern and composition by nacked eye observation, optical microscopic observation ofground and decalcified section, X-ray diffraction method and amino acid analysis.
In the arrangement pattern and morphology of the teeth, Chlamydoselachus is very similar toCladoselache, a Devonian shark. Therefore, it is considered that Chlamydoselachus has one of themost primitive shark teeth type.
The hard tissues of the tooth is consist of outer, inner and basal layer. The outer layer ishighly calcified tissue which covers the crown of the tooth. The inner layer is penetrated by ra-dial dentinal tubules extending from the dental pulp cavity. The basal layer is a osseous tissuewhich contains many small cavities. The tooth is supported on the jaws by both Sharpey's fiberswhich connect the basal layer of the tooth to the surrounding fibrillar connective tissue layer, and the epithelial attachment, the extension of the oral mucous epithelium.
Also, this study made clear, that in Chlamydoselachus, the major mineral component of thetooth hard tissues is apatite, and the protein which is contained in the tooth hard tissues iscollagen.

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