Delatte Myriam, Von den Hoff Johannes W, van Rheden René E M, Kuijpers-Jagtman Anne M
Department of Orthodontics, Université Catholique de Louvain, Cliniques Universitaires St Luc, Brussels, Belgium.
Eur J Oral Sci. 2004 Apr;112(2):156-62. doi: 10.1111/j.0909-8836.2004.00108.x.
Primary and secondary cartilages differ in embryonic origin and in histological organization, and are generally considered to have a different mode of growth. However, few studies have directly compared the two types of cartilage of the same animal at the same age. Therefore, we analysed several histological and biochemical differences between secondary cartilage of the mandibular condyle and primary cartilage of the femoral head of 4-d-old rats. We evaluated the tissue organization, the level of DNA and glycosaminoglycan (GAG) synthesis, and the GAG and collagen content. The expression of collagen types I, II and III and of receptors for insulin-like growth factor (IGF)-I, fibroblast growth factor (FGF), and transforming growth factor (TGF)-beta were investigated by immunohistochemistry. The ex vivo DNA and GAG synthesis as well as the GAG content of femoral heads were much higher than that of mandibular condyles. Mandibular condyles expressed both collagen types I and II, while femoral heads expressed only type II collagen. In the mandibular condyles, receptors for IGF-I, FGF, and TGF-beta were observed mainly in the superficial layers, whereas they were found throughout the entire femoral head. In conclusion, major differences were found between both types of cartilage, which might be related to their specific functional demands.
原发性软骨和继发性软骨在胚胎起源和组织学结构上存在差异，通常被认为具有不同的生长方式。然而，很少有研究直接比较同一年龄段同一动物的这两种软骨。因此，我们分析了4日龄大鼠下颌髁突继发性软骨和股骨头原发性软骨之间的一些组织学和生化差异。我们评估了组织结构、DNA和糖胺聚糖（GAG）合成水平以及GAG和胶原蛋白含量。通过免疫组织化学研究了I型、II型和III型胶原蛋白以及胰岛素样生长因子（IGF）-I、成纤维细胞生长因子（FGF）和转化生长因子（TGF）-β受体的表达。股骨头的体外DNA和GAG合成以及GAG含量远高于下颌髁突。下颌髁突同时表达I型和II型胶原蛋白，而股骨头仅表达II型胶原蛋白。在下颌髁突中，IGF-I、FGF和TGF-β受体主要在表层观察到，而在整个股骨头中均有发现。总之，两种软骨之间存在主要差异，这可能与其特定的功能需求有关。
