ブタ Sus scrofa domesticus とニホンイノシシ Sus scrofa leucomystax の下顎骨についての比較形態学的研究
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Both pigs and wild boars belong to the artiodactyla and show the same dental formula as the mammalia. The former is said to be the domesticated form of the latter. Therefore, various common and different points between them are conceivable. For the present study, mandible, a part of the skull, were examined with instruments and macroscopically to determine and analyze the differences in size and morphology. The materials consisted of 73 bleached mandible with the second or the third posterior cheek teeth erupted, obtained from 29 pigs and 44 wild boars captured in Hiroshima and Yamaguchi Prefectures. The results were as follows : 1. In order to gain a grasp of the overall size of the mandible, the mandibular length, height of mandibular ramus and breadth of mandibular angle were selected from among many items for measurement. The pigs showed higher values in each item than the wild boars. The height of the mandibular ramus in particular was remarkable. In comparison of coefficient of correlation between any two items, the wild boars showed a much positive correlation and appeared to be well-proportioned. 2. In addition to the foregoing three items, measurements were taken of and indexes were calculated for 17 items. A test of significant difference on the averages was made for both the pigs and the wild boars about each item. Those in which no difference was recognized were : indexes of mandibular notch, indexes of mandibular breadth, and indexes of head of mandible. Significant differences were recognized in all other items. The pig showed greater value than the wild boars. 3. For macroscopic observation, the degree of growth, for both groups, was examined of the following six items : mylohyoid line, genial tubercles, mylohyoid groove, tuberosity of masseter muscle, pterygoid tuberosity and pterygoid fossa. As a result, significant differences were recognized in mylohyoid line and pterygoid tuberosity for both groups. A better growth was indicated for the pigs than for the wild boars. 4. The mental foramen was classified from the anteriority into the anterior, middle, and posterior mental foramen. The position of the anterior mental foramen between I_1 and I_2 teeth was most frequent for both groups and accounted for about 50%. The position of the middle mental foramen at P_1 tooth was most frequent for both groups and accounted for about 60%. The position of the posterior mental foramen was spread widely for both groups. The most frequent position was at P_3 tooth for the pigs and at the distal side of P_4 tooth for the wild boars. The forward-upward direction of the anterior mental foramen accounted for about 90% in both group. The most frequent direction of the middle mental foramen was forward for the pigs and forward-upward for the wild boars. The most frequent direction the posterior mental foramen was outward for the pigs, which accounted for 28% and rearward-upward for the wild boars, which accounted for 51%. The position of mental foramen in the body of the mandible excluding the posterior mental foramen was higher in the pigs than in the wild boars. The height of foramen for the pigs decreased, 71-62-58%, from the anterior to posterior mental foramen, whereas it increased, 56-59-64%, for the wild boars. 5. The diameter of mandibular foramen was 18mm for the pigs and 11mm for the wild boars. The position of foramen was situated at the middle part of the mandibular ramus for the pigs and from the tip of the condyloid process, the position of 60% in height of the mandibular ramus for the wild boars. The wild boars' were positioned slightly lower than the pigs'. 6. On the basis of the foregoing, the pigs, because of their heavier weight, exceeded the wild boars in length in almost all parts. The height of mandibular ramus in particular showed an excellent growth. The wild boars, however, seemed to exceed the pigs in the proportion on length of the overall mandible. It is presumed that such differences arise from the fact that one is an artificial strain, while the other is a wild strain.
- 1980-05-25
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関連論文
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- ブタ Sus scrofa domesticus とニホンイノシシ Sus scrofa leucomystax の下顎骨についての比較形態学的研究 : 主論文の要旨
- ブタ Sus scrofa domesticus とニホンイノシシ Sus scrofa leucomystax の下顎骨についての比較形態学的研究