Luder H U
Department of Oral Structural Biology, University of Zürich, Switzerland.
J Anat. 1994 Dec;185 ( Pt 3)(Pt 3):587-98.
In an attempt to determine the contribution of the perichondrial and endochondral components to rapid and slow overall condylar growth, mandibular condyles from rats aged 21 and 45 d as well as 3 and 6 months were examined by light microscopy. A morphometric analysis served to estimate the size of cells and the amount of extracellular matrix per cell in the various tissue layers beneath the articular surface. Quantitative evaluation of autoradiographic labelling due to the presence of [3H]-thymidine, [3H]-proline, and [35S]-sulphate 1.5 or 2 h and 5 d after injection of the tracer was used to determine the velocity of overall condylar growth. A combination of the two types of results allowed the calculation of daily rates in (1) the generation of new chondrocytes, constituting the perichondrial growth component, and the endochondral components comprising (2) net accumulation of extracellular matrix in the cartilage and (3) enlargement of the chondrocytes. It was observed that the 3 factors contributed, respectively, by about 10-25, 30 and 45-60% to rapid growth and by about 75, 15 and 10% to slow growth. Thus when growth slowed, the contribution of chondrocyte enlargement declined markedly and that of matrix accumulation slightly, while the contribution of new cell generation increased correspondingly. Declines in chondrocyte enlargement and in accumulation of cartilage matrix that was related mainly to decreasing proteoglycan formation were in good agreement with age-associated variation in weight gain, while peak rates in generation of new chondrocytes appeared to be delayed against peak somatic growth. It is concluded that (1) endochondral components contribute most to particularly rapid condylar growth, exceeding the perichondrial component, and (2) endochondral components of condylar growth are regulated by systemic factors that also control somatic growth.
为了确定软骨膜和软骨内成分对髁突整体快速和缓慢生长的贡献，对21日龄、45日龄、3月龄和6月龄大鼠的下颌髁突进行了光学显微镜检查。形态计量分析用于估计关节表面下方各组织层中细胞的大小和每个细胞的细胞外基质量。通过注射示踪剂后1.5或2小时以及5天，对由于存在[3H]-胸腺嘧啶、[3H]-脯氨酸和[35S]-硫酸盐而产生的放射自显影标记进行定量评估，以确定髁突整体生长的速度。将两种类型的结果结合起来，可以计算出以下各项的每日速率：(1)构成软骨膜生长成分的新软骨细胞的生成，以及软骨内成分，包括(2)软骨中细胞外基质的净积累和(3)软骨细胞的增大。观察到这三个因素分别对快速生长贡献约10-25%、30%和45-60%，对缓慢生长贡献约75%、15%和10%。因此，当生长减慢时，软骨细胞增大的贡献显著下降，基质积累的贡献略有下降，而新细胞生成的贡献相应增加。软骨细胞增大和软骨基质积累的下降主要与蛋白聚糖形成的减少有关，这与体重增加的年龄相关变化一致，而新软骨细胞生成的峰值速率似乎相对于体细胞生长的峰值有所延迟。得出的结论是：(1)软骨内成分对髁突特别快速的生长贡献最大，超过软骨膜成分；(2)髁突生长的软骨内成分受也控制体细胞生长的全身因素调节。
