van Turnhout Mark C, Schipper Henk, Engel Bas, Buist Willem, Kranenbarg Sander, van Leeuwen Johan L
Wageningen University, Department of Animal Sciences, Experimental Zoology Group, 6700 AH Wageningen, the Netherlands.
BMC Dev Biol. 2010 Jun 7;10:62. doi: 10.1186/1471-213X-10-62.
Articular cartilage (AC) is the layer of tissue that covers the articulating ends of the bones in diarthrodial joints. Across species, adult AC shows an arcade-like structure with collagen predominantly perpendicular to the subchondral bone near the bone, and collagen predominantly parallel to the articular surface near the articular surface. Recent studies into collagen fibre orientation in stillborn and juvenile animals showed that this structure is absent at birth. Since the collagen structure is an important factor for AC mechanics, the absence of the adult Benninghoff structure has implications for perinatal AC mechanobiology. The current objective is to quantify the dynamics of collagen network development in a model animal from birth to maturity. We further aim to show the presence or absence of zonal differentiation at birth, and to assess differences in collagen network development between different anatomical sites of a single joint surface. We use quantitative polarised light microscopy to investigate properties of the collagen network and we use the sheep (Ovis aries) as our model animal.
Predominant collagen orientation is parallel to the articular surface throughout the tissue depth for perinatal cartilage. This remodels to the Benninghoff structure before the sheep reach sexual maturity. Remodelling of predominant collagen orientation starts at a depth just below the future transitional zone. Tissue retardance shows a minimum near the articular surface at all ages, which indicates the presence of zonal differentiation at all ages. The absolute position of this minimum does change between birth and maturity. Between different anatomical sites, we find differences in the dynamics of collagen remodelling, but no differences in adult collagen structure.
The collagen network in articular cartilage remodels between birth and sexual maturity from a network with predominant orientation parallel to the articular surface to a Benninghoff network. The retardance minimum near, but not at, the articular surface at all ages shows that a zonal differentiation is already present in the perinatal animals. In these animals, the zonal differentiation can not be correlated to the collagen network orientation. We find no difference in adult collagen structure in the nearly congruent metacarpophalangeal joint, but we do find differences in the dynamics of collagen network remodelling.
关节软骨（AC）是覆盖在滑膜关节骨的关节端的一层组织。在不同物种中，成年AC呈现出一种拱廊状结构，在靠近骨的部位，胶原蛋白主要垂直于软骨下骨，而在靠近关节面的部位，胶原蛋白主要平行于关节面。最近对死产和幼年动物胶原蛋白纤维取向的研究表明，这种结构在出生时并不存在。由于胶原蛋白结构是影响AC力学性能的一个重要因素，成年本宁霍夫结构的缺失对围产期AC的力学生物学具有重要意义。当前的目标是量化模型动物从出生到成熟过程中胶原蛋白网络发育的动态变化。我们进一步旨在揭示出生时是否存在区域分化，并评估单个关节表面不同解剖部位之间胶原蛋白网络发育的差异。我们使用定量偏振光显微镜来研究胶原蛋白网络的特性，并以绵羊（Ovis aries）作为我们的模型动物。
围产期软骨在整个组织深度内，主要胶原蛋白取向平行于关节面。在绵羊达到性成熟之前，这种结构会重塑为本宁霍夫结构。主要胶原蛋白取向的重塑始于未来过渡区下方的深度。组织延迟在所有年龄段都在关节面附近显示出最小值，这表明在所有年龄段都存在区域分化。这个最小值的绝对位置在出生和成熟之间确实会发生变化。在不同解剖部位之间，我们发现胶原蛋白重塑的动态变化存在差异，但成年胶原蛋白结构没有差异。
关节软骨中的胶原蛋白网络在出生到性成熟之间从主要取向平行于关节面的网络重塑为本宁霍夫网络。在所有年龄段，靠近但不在关节面处的延迟最小值表明围产期动物中已经存在区域分化。在这些动物中，区域分化与胶原蛋白网络取向无关。我们发现几乎全等的掌指关节中成年胶原蛋白结构没有差异，但我们确实发现胶原蛋白网络重塑的动态变化存在差异。
