スナネズミ Meriones unguiculatus の下顎臼歯の形態学的, 組織学的構造について
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概要
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The mandibular molars of 30 Mongolian gervil, Meriones unguiculatus weighing about 70 grams each were examined morphologically and histologically. After the molars were soft X-rayed, some were prepared for examination on a dissecting microscope and the others as non-decalcified or decalcified sections. The sectioned specimens were stained by methyleneblue-fuchsin and hematoxylin-eosin. The results were as follows : 1. The first molars consisted of three lobes, second molars two lobes, and third molars one lobe. All the lobes were cylindrical. 2. Each molar had a flat occlusal surface but no cusps or fissures. 3. The first molars had three roots each (mesial, distal and central), second molars two roots (mesial and distal), and third molars a single root. 4. The crowns were long and the roots were comparative short. Their ratios were 1 : 1 or 1.5 : 1 approximately. 5. Most of the enamel surface facing the isthmus was covered with a thin layer of acellular coronal cementum. In the portion enclosed by this layer was dental sac-like connective tissue, in which globular cementum was seen. 6. On the enamel surface of the cervical line portion also, coronal cementum which is an extension of acellular root cementum was seen. 7. Cellular and acellular cementum were identified on the lower half surface of root dentin and only acellular cementum on the upper half surface. 8. The root apex of each molar was slightly open except that of the central root of the first molar. On the basis of these finding, the morphological structure of the molars examined resembled that of the herbivorous animals, especially semihypselodont of the cattle.
- 九州歯科学会の論文
- 1984-08-25