ヒト下顎骨骨皮質形成の加齢に伴う組織学的変化
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概要
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A histological study on the human mandible was performed, using large celloidin-embedded sections of a total of 63 human mandibles. All the materials were autopsy cases with the range from a 11.8cm crown-heel length fetus to the age of 63 years. The histological study was focused on the chronological as well as developmental changes of the mandibular cortex and the periosteal tissue. Results were summarized as follows : I. Developmental process of the cortex Cortex of a 11.8cm fetus already showed a spongy appearance consisting of fibrous bone. A. Maturation process of the cortex The focal appearance of lamellar bone was noted first in the fibrous bone of a 18.0cm fetus. A 31.0cm fetus had the cortex consisting entirely of a mixture of fibrous and lamellar bones. Moreover, in a 34.0cm fetus, the cortex of the mandibular body was composed entirely of lamellar bone. In a 3-month-old infant, the whole cortex consisted entirely of lamellar bone, and no further histologic changes were observed. From a viewpoint of anatomic sites, the lamellar bones appeared firstly and simultaneously in the body, angle and ramus, and appeared subsequently in the condylar process, incisor region and finally in the coronoid process. B. Consolidation of the cortex A 23.0cm fetus exhibited the focal appearance of band-like tissue in the spongy bone. In a 2-year-old infant the entire contex consisted of a mixture of spongy and band-like tissue. The entire replacement of the cortex by band-like tissue was observed first in the body of 39.5cm fetus and was noted in the whole cortex in a 5-year-old child. No further subsequent changes were seen. From a viewpoint of anatomic locations, the band-like consolidation was noted in the body, ramus, coronoid process, condylar process, incisor region and angle in order of the occurrence. II. Developmental process of the bone in the subperiosteal tissue Eosinophilic and amorphous material which appeared in early fetal period was the most primitive precursor of the bone. This material changed to bone-like tissue, and then to usual new bone tissue. In terms of the chronological relation with formation of the cortex, the above histologic changes in the subperiosteal tissue, including eosinophilid amorphous material, bone-like tissue, usual new bone tissue and usual mature bone tissue, occurred in the period, when the cortex exhibited the maturation process from fibrous and spongy tissue to lamellar and band-like tissue. Moreover, both tissues showed body fusion, resulting in the appearance of usual bone cortex at the age of 5 years. There were no further chronological change. III. Osteoporosis The first osteoporotic change was observed in the incisor region of a 44-year-old case, showing dilated vessels and fibrosis in Harversian canals. Subsequently this osteoporotic changes were noted in the body angle, coronoid process, condylar process and ramus in order of the appearance. Fat cells were also noted in a 58-year-old case.
- 九州歯科学会の論文
- 1996-02-25