兎胎仔下顎頭の構造に関する観察

抄録

The role of the mandibular condyle in the cranio-facial growth and development still remains unknown in spite that it is considered to be very important in orthodontics.
The author made observations on the mandibular condyle of prenatal rabbits with light microscopy and transmission electron microscopy to learn about the characteristic of this structure and to clarify the mechanism of the growth and development of the mandibular condyle.
The results were as follows:
1. The fibrous and subfibrous cell zones which form the surface of the mandibular condyle continue to the periosteum of the mandibular ramus.
2. The osteo-chondro progenitor cell zone is observed beneath the subfibrous cell zone at the tip of the mandibular condyle. This zone continues to the osteoprogenitor cell zone in the lateral area of the condyle and furthermore preosteoblasts and osteoblasts are observed in the direction of the mandibular ramus.
3. In the profound layer of the osteo-chondroprogenitor cell zone the chondroblastic zone, the chondrocytic zone and hypertrophic cell zone are observed in the cartilage area.
4. In the lateral area of the mandibular condyle three zones are identified: the osteoprogenitor cell zone, preosteoblastic zone and osteoblastic zone, inward from the subfibrous cell zone. And the collar bone is formed adjacent to the calcified cartilage of the hypertrophic cell zone of the cartilage area.