Breur G J, Turgai J, Vanenkevort B A, Farnum C E, Wilsman N J
Department of Comparative Biosciences, University of Wisconsin, Madison 53706.
Anat Rec. 1994 Jul;239(3):255-68. doi: 10.1002/ar.1092390304.
It has been suggested that within the growth plate, the final volume and shape of hypertrophic chondrocytes are important variables in determining the rate of longitudinal bone growth. To better understand the organization and regulation of chondrocytic hypertrophy as related to longitudinal bone growth, the beginning and end, and the location and magnitude of chondrocytic volume and shape changes during the hypertrophic process were defined in the proximal tibial growth plate of 35-day-old rats.
In this study we used two different approaches, a stereological analysis of chondrocytes in unbiasedly defined, narrow growth plate strata, and a serial section reconstruction and measurement of individual cells. In both experiments chondrocytes were preserved using optimal chemical fixation. Proliferating chondrocytes were identified using bromodeoxyuridine labelling, and the rate of longitudinal bone growth was determined using oxytetracycline labelling.
In both studies, immediately following cell division in the proliferative zone, chondrocytic volume gradually increased toward the mid-point of the growth plate. During this phase of about 30 hours, approximately 20% of the final cell volume was obtained. During the following 20 hours the remaining 80% was acquired. The estimated rate of cell volume increased changed from approximately 50 microns 3/hr during the first 30 hours to about 800 microns 3/hr during the last 20 hours. The increase in cell volume resulted in an increase in both the vertical and the horizontal chondrocytic diameters. Cell parameters did not change during the final five hours of the maturation process.
In this study we demonstrated that chondrocytic enlargement starts immediately following cell division in the proliferative zone, and that chondrocytic enlargement consists of two morphologically distinguishable phases. The transition point between the first and the second phase of chondrocytic enlargement corresponded with the junction between the proliferative zone and the maturation zone.
有人提出，在生长板内，肥大软骨细胞的最终体积和形状是决定纵向骨生长速率的重要变量。为了更好地理解与纵向骨生长相关的软骨细胞肥大的组织和调节，在35日龄大鼠的胫骨近端生长板中确定了肥大过程中软骨细胞体积和形状变化的起始和结束、位置和大小。
在本研究中，我们使用了两种不同的方法，即对无偏定义的狭窄生长板层中的软骨细胞进行体视学分析，以及对单个细胞进行连续切片重建和测量。在两个实验中，软骨细胞均采用最佳化学固定法保存。使用溴脱氧尿苷标记鉴定增殖的软骨细胞，并使用土霉素标记确定纵向骨生长速率。
在两项研究中，增殖区细胞分裂后，软骨细胞体积立即开始逐渐向生长板中点增加。在大约30小时的这个阶段，获得了最终细胞体积的约20%。在接下来的20小时内，获得了剩余的80%。估计的细胞体积增加速率从最初30小时的约50立方微米/小时变化到最后20小时的约800立方微米/小时。细胞体积的增加导致软骨细胞垂直和水平直径均增加。在成熟过程的最后五小时内，细胞参数没有变化。
在本研究中，我们证明软骨细胞增大在增殖区细胞分裂后立即开始，并且软骨细胞增大由两个形态上可区分的阶段组成。软骨细胞增大的第一阶段和第二阶段之间的过渡点与增殖区和成熟区之间的交界处相对应。
