발육중인 생쥐 하악 과두에서 연골 및 골의 특이 유전자 발현 = Expression of mRANs characteristic of cartilage and bone in the developing mandibular condyle of mice

국문 초록 (Abstract)

하악과두 연골이 발생하고 분화하는 과정에서 나타내는 특성을 규명하기 위하여, 발생 16, 18일과 출생 1일, 5일, 10일, 20일 및 30일 후의 ICR생쥐의 하악과두를 형태학적으로 분석하고, 생쥐 Ⅰ형, Ⅱ형, X형 교원질, Indian hedgehog(IHH) 및 BMP-4 등의 mRNA 발현을 in-situ hybridization 방법으로 연구하였다.
1. 생쥐 Ⅰ형 및 Ⅱ형 교원질 mRNA는 하악과두의 발생 및 성장과정에서 모두 발현되었다. Ⅰ형 교원질 mRNA는 휴지층과 증식층의 상부에서 관찰된 반면 Ⅱ형 교원질은 휴지층과 증식층 그리고 비대연골층의 상부에서 관찰되었다.
2. 하악과두 연골은 성장에 따라 비대연골층이 계속 증가하는 소견을 보였으며, 비대 연골층의 세포들은 특징적으로 X형 교원질 mRNA의 발현을 보였다.
3. BMP-4 mRNA는 하악과두 연골 원기와 골화중인 하악골체에서 모두 발현되었다.
4. IHH mRNA는 하악과두의 발생과정에서 증식 연골층의 하부와 비대연골층의 상부에서 선택적으로 관찰되었다.

다국어 초록 (Multilingual Abstract)

It has not been elucidated whether the initiation of condylar development of the mandible is related with the periosteum of the mandible, or if it derives from a separate programmed blastema not related with the mandible. Also, although the mandibular condylar cartilage is known to promote growth, few studies have dealt with molecular-biologic mechanisms such as the expression of specific genes according to the differentiation of the mandibular condyle.
To elucidate the unique cellular characteristics, development, and differentiation process of the mandibular condyle, an examination of expressions of genes characteristic of cartilage and bone were carried out using RT-PCR and mRNA in situ hybridization.
1. Type?collagen mRNA was detected with type Ⅱ collagen mRNA in the differentiation and growth process of the cartilage of the mandibular condyle. Type Ⅱ collagen mRNA was demonstrated in the whole resting and upper part of the proliferative zone, whereas type Ⅱ collgen mRNA was observed in the resting, proliferative and upper hypertrophic cartilage zone of the mandibular condyle.
2. The condylar cartilage rapidly increased in size due to the accumulation of hypertrophic chondrocytes as characterized by the expression of type Ⅱ collagen mRNA during postnatal development.
3. BMP-4 mRNA was present in the anlage of the future condylar process and also in the ossifying mandibular body.
4. IHH mRNA was limited exclusively to the lower part of the proliferative zone and the upper part of the hypertrophic cartilage zone during condylar development.
These findings were different from those in the growth-plate cartilage of the long bone, indicating a characteristic feature of the differentiation of the chondrocytes in the condylar cartilage present in prenatal and postnatal development. Furthermore, it was also suggested that chondroblasts of condylar cartilage rapidly differentiate into hypertrophic chondrocytes with increased functional Load force such as muscle activity and mastication.

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